1994_Harris_Transient_Voltage_Suppression_Devices 1994 Harris Transient Voltage Suppression Devices

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HARRIS SEMICONDUCTOR TRANSIENT
VOLTAGE SUPPRESSION
This Transient Voltage Suppression Databook represents the full line of Harris
Semiconductor Transient Voltage products for commercial and military
applications and supersedes previously published Transient Voltage material
under the Harris, GE, RCA or Intersil names. For a complete listing of all
Harris Semiconductor products, please refer to the Product Selection Guide
(PSG-201.21; ordering information below).
For complete, current and detailed technical specifications on any Harris
devices please contact the nearest Harris sales, representative or distributor
office. Literature requests may also be directed to:

Harris Semiconductor Literature Department
P.O. Box 883, MS 53-204
Melbourne, FL 32902
Phone: 1-800-442-7747
Fax: 407-724-7240
See Section 14 for Information Available on AnswerFAX, 407-724-7800

u.s. HEADQUARTERS

EUROPEAN HEADQUARTERS

Harris Semiconductor
P. O. Box 883, Mail Stop 53·210
Melbourne, FL 32902
TEL: 1-800-442-7747
(407) 729-4984
FAX: (407) 729-5321

Harris Semiconductor
Mercure Center
100, Rue de la Fusee
1130 Brussels, Belgium
TEL: 32272421 11

SOUTH ASIA

NORTH ASIA

Harris Semiconductor H.K. Ltd
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TEL: (852) 723-6339

Harris K.K.
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Chiyoda-ku, Tokyo 102 Japan
TEL: (81) 3-3265-7571
TEL: (81) 3-3265-7572 (Sales)

See our
specs in

CAPS
CECC

CANADIAN STANDARDS
ASSOCIATION

I.SJlSO 9000lEN 29000

Copyright © Harris Corporation 1993
(All rights reserved)
Printed in U.S.A., 1993

UNDERWRITERS
LABORATORY

Ha"is Semiconductor products are sold by description only. All specifications in this product
guide are applicable only to packaged products; specifications for die are available upon
request. Ha"is reserves the right to make changes in circuit design. specifications and other
information at any time without prior notice. Accordingly. the reader is cautioned to verify that
information in this publication is current before placing orders. Reference to products of other
manufecturers are solely for convenience of comparison and do not imply total equivalency of
design. performance. or otherwise.

ii

TRANSIENT VOLTAGE SUPPRESSION
FOR COMMERCIAL AND MILITARY APPLICATIONS

Voltage Transients - An Overview
Transient Suppression - Devices and Principles
Varistors - Basic Properties, Terminology and Theory
Designing With Varistors
Suppression - Telecommunication Systems
Suppression - Automotive Transients
Varistor Testing
Quality and Reliability
Varistor Products
Surgector Products
Protection Circuits
Application Notes
High Reliability Series
Datasheets By FAX, Harris AnswerFAX
Sales Offices
Index

iii

TECHNICAL ASSISTANCE
For technical assistance on the Harris products listed in this databook,
please contact the Field Applications Engineering staff available at one of the following Harris Sales Offices:
UNITED STATES

CALIFORNIA

Calabasas ......................... 818-878-7950
Costa Mesa ........................ 714-433-0600
San Jose .......................... 408-985-7322

FLORIDA

Palm Bay .......................... 407-729-4984

GEORGIA

Duluth ............................. 404-476-2035

ILLINOIS

Schaumburg ........................ 708-240-3480

INDIANA

Carmel ............................ 317-843-5180

MASSACHUSETTS

Burlington .......................... 617-221-1850

NEW JERSEY

Voorhees .......................... 609-751-3425

NEW YORK

Hauppauge ......................... 516-342-0291
Wappingers Falls .................... 914-298-1920

TEXAS

Dallas ............................. 214-733-0800

INTERNATIONAL

FRANCE

Paris. . . . . . . . . . . . . . . . . . . . . . . . . . . . 33-1-346-54046

GERMANY

Munich ........................... 49-89-63813-0

HONG KONG

Kowloon ........................... 852-723-6339

ITALY

Milano ............................ 39-2-262-0761

JAPAN

Tokyo ........................... 81-3-3265-7571

KOREA

Seoul .. . . . . . . . . . . . . . . . . . . . . . . . . . . 82-2-551-0931

SINGAPORE

Singapore ........................... 65-291-0203

TAIWAN

Taipei ........................... 886-2-716-9310

UNITED KINGDOM

Camberley ....................... 44-2-766-86886

For literature requests, please contact Harris at 1-800-442-7747 (1-800-4HARRIS) or call
Harris AnswerFAX for immediate fax service at 407-724-7800

iv

MOV Index
MODEL NUMBER

PAGE

MODEL NUMBER

PAGE

MODEL NUMBER

PAGE

V452AS32

9-12

V502AS32

9-12

V150LA20C

9-27

V300LA20C

9-27

V602AS32

9-12

V150LA20CX360

9-27

V300LA40C

9-27

V452AS42

9-12

V175LA10C

9-27

V300LA40CX745

9-27

V502AS42

9-12

V175LA20C

9-27

V131CA32

9-35

V602AS42

9-12

V175LA20CX425

9-27

V131CA40

9-35

V452AS52

9-12

V230LA20C

9-27

V151CA32

9-35

V502AS52

9-12

V230LA40C

9-27

V151CA40

9-35

V602AS52

9-12

V230LA40CX570

9-27

V251CA32

9-35

V150LA10C

9-27

V275LA40CX680

9-27

V302AS60

9-12

V250LA20C

9-27

V251CA40

9-35

V332AS60

9-12

V250LA40C

9-27

V251CA60

9-35

V402AS60

9-12

V250LA40CX620

9-27

V271CA32

9-35

V18AUMLA1210

9-15

V275LA20C

9-27

V271CA40

9-35

V18AUMLA1812

9-15

V275LA40C

9-27

V271CA60

9-35

V18AUMLA2220

9-15

V275LA40CX680

9-27

V321CA32

9-35

V151BA60

9-23

V300LA2OC

9-27

V321CA40

9-35

V251BA60

9-23

V300LA40C

9-27

V321CA60

9-35

V271BA60

9-23

V300LA40CX745

9-27

V421CA32

9-35

V321BA60

9-23

V130LA10C

9-27

V421CA40

9-35

V421BA60

9-23

V130LA20C

9-27

V421CA60

9-35

V481BA60

9-23

V130LA20CX325

9-27

V481CA32

9-35

V511BA80

9-23

V140LA10C

9-27

V481CA40

9-35

V571BA60

9-23

V140LA20C

9-27

V481CA60

9-35

V661BA60

9-23

V140LA20CX340

9-27

V511CA32

9-35

V751BA60

9-23

V150LA10C

9-27

V511CA40

9-35

V881BA60

9-23

V150LA20C

9-27

V511CA60

9-35

Vl12BB60

9-23

V150LA20CX360

9-27

V571CA32

9-35

V142BB60

9-23

V175LA10C

9-27

V571CA40

9-35

V172BB60

9-23

V175LA20C

9-27

V571CA60

9-35

V202BB60

9-23

V175LA20CX425

9-27

V661CA32

9-35

V242BB60

9-23

V230LA20C

9-27

V661CA40

9-35

V282BB60

9-23

V230LA40C

9-27

V661CA60

9-35

V130LA1OC

9-27

V230LA40CX570

9-27

V751CA32

9-35

V130LA2OC

9-27

V250LA20C

9-27

V751CA40

9-35

V130LA2OCX325

9-27

V250LA40C

9-27

V751CA60

9-35

V140LA1OC

9-27

V250LA40CX620

9-27

V881CA60

9-35

V140LA2OC

9-27

V275LA20C

9-27

Vl12CA60

9-35

Vl40LA2OCX340

9-27

V275LA40C

9-27

V142CA60

9-35

v

MOV Index (Continued)
MODEL NUMBER

PAGE

MODEL NUMBER

PAGE

MODEL NUMBER

PAGE

9-49

V130LA1

9-60

9-35

V22CS22

9-49

V130LA2

9-60

V242CA60

9-35

V26CS22

9-49

V130LA5

9-60

V282CA60

9-35

V31CS22

9-49

V130LA10A

9-60

V18CH8

9-40

V38CS22

·9-49

V130LA20A

9-60

V22CH8

9-40

V131DA40

9-52

V130LA20B

9-60

V27CH8

9-40

V151DA40

9-52

V140LA2

9-60

V33CH8

9-40

V251DA40

9-52

V140LA5

9-60

V39CH8

9-40

V271DA40

9-52 .

V140LA10A

9-60

V47CH8

9-40

V321DA40

9-52

V150LA1

9-60

V56CH8

9-40

V421DA40

9-52

V150LA2

9-60

V68CH8

9-40

V481DA40

9-52

V150LA5

9-60

V82CH8

9-40

V511DA40

9-52

V150LA10A

9-60

V10OCH8

9-40

V571DA40

9-52

V150LA20A

9-60

V12OCH8

9-40

V661DA40

9-52

V150LA20B

9-60
9-60

V172CA60

9-35

V18CS22

V202CA60

V15OCH8

9-40

V751DA4O

9-52

V175LA2

V18OCH8

9-40

V131HA32

9-56

V175LA5

9-60

V20OCH8

9-40

V131HA40

9-56

V175LA10A

9-60

V22OCH8

9-40

V151HA32

9-56

V175LA20A

9-60

V24OCH8

9-40

V151HA40

9-56

V230LA4

9-60

V36OCH8

9-40

V251HA32

9-56

V230LA10

9-60

V39OCH8

9-40

V251HA40

9-56

V230LA20A

9-60

V43OCH8

9-40

V271HA32

9-56

V250LA2

9-60

V8CP22

9-44

V271HA40

9-56

V250LA4

9-60

V14CP22

9-44

V321HA32

9-56

V250LA10

9-60

V31CP22

9-44

V321HA40

9-56

V250LA20A

9-60

V38CP22

9-44

V421HA32

9-56

V250LA40A

9-60

V13OCP22

9-44

V421HA40

9-56

V250LA40B

9-60
9-60

V15OCP22

9-44

V481HA32

9-56

V275LA2

V31CP20

9-44

V481HA40

9-56

V275LA4

9-60

V38CP20

9-44

V511HA32

9-56

V275LA10

9-60

V13OCP20

9-44

V511HA40

9-56

V275LA20A

9-60

V15OCP20

9-44

V571HA32

9-56

V275LA40A

9-60

9-60

V38CP16

9-44

V571HA40

9-56

V275LA40B

V13OCP16

9-44

V661HA32

9-56

V300LA2

9-60

V15OCP16

9-44

V661HA40

9-56

V300LA4

9-60

V8CS22

9-49

V751HA32

9-56

V320LA20A

9-60

V14CS22

9-49

V751HA40

9-56

V320LA40B

9-60

vi

-MOV Index (Continued)
MODEL NUMBER

PAGE

MODEL NUMBER

PAGE

MODEL NUMBER

PAGE

V420LA10

9-60

V82MA3B

~

V421NA34

9-81

V420LA20A

9-60

V82MA3S

9-68

V481NA34

9-81

V420LA40B

9-60

V100MA4A

9-68

V511NA34

9-81

V480LA40A

9-60

V100MA4B

9-68

V571NA34

9-81

V480LA80B

9-60

V100MA4S

9-68

V661NA34

9-81

V510LA40A

9-60

V120MA1A

9-68

V751NA34

9-81

V510LA80B

9-60

V120MA2B

9-68

Vl30PA20A

9-85

V575LA40A

9-60

V120MA2S

9-68

V130PA2OC

9-85

V575LA80B

9-60

V150MA1A

9-68

V150PA20A

9-85

V660LA50A

9-60

V150MA2B

9-68

Vl50PA2OC

9-85

V660LA100B

9-60

V180MA1A

9-68

V250PA40A

9-85

V1000LA80A

9-60

V180MA3B

9-68

V250PA4OC

9-85

V1000LA160B

9-60

V220MA2A

9-68

V275PA40A

9-85

V18MA1A

~

V220MA4B

9-68

V275PA4OC

9-85

V18MA1B

9-68

V270MA2A

~

V320PA40A

9-85

V18MA1S

9-68

V270MA4B

9-68

V320PA4OC

9-85

V22MA1A

9-68

V330MA2A

9-68

V420PA40A

9-85

V22MA1B

~

V330MASB

9-68

V420PA4OC

9-85

V22MA1S

9-68

V390MA3A

9-68

V480PA80A

9-85

V27MA1A

~

V390MA6B

9-68

V480PA8OC

9-85

V27MA1B

9-68

V430MA3A

9-68

V510PA80A

9-85

V27MA1S

~

V430MA7B

9-68

V510PA8OC

9-85

V33MA1A

9-68

V3.5MLA1206

9-73

V575PA80A

9-85

V33MA1B

9-68

V5.5MLA1206

9-73

V575PA80A

9-85

V33MA1S

9-68

V14MLA1206

9-73

V660PA100A

9-85

V39MA2A

~

V18MLA1206

9-73

V660PA100C

9-85

V39MA2B

9-68

V18MLA1210

9-73

V8RAS

9-89

V39MA2S

~

V26MLA1206

9-73

V12RA8

9-89

V47MA2A

~

V26MLA1210

9-73

V18RA8

9-89

V47MA2B

~

V33MLA1206

9-73

V22RA8

9-89

V47MA2S

~

V42MLA1206

9-73

V27RA8

9-89

V56MA2A

~

V56MLA1206

9-73

V33RA8

9-89

V56MA2B

9-68

V68MLA1206

9-73

V39RA8

9-89
9-89
9-89

V56MA2S

9-68

V131NA34

9-81

V47RA8

V68MA3A

9-68

V151NA34

9-81

V56RA8

V68MA3B

9-68

V251NA34

9-81

V68RA8

9-89

V68MA3S

~

V271NA34

9-81

V82RA8

.9-89

V82MA3A

9-68

V321NA34

9-81

V100RA8

9-89

vii

MOV Index (Continued)
MODEL NUMBER

PAGE

MODEL NUMBER

PAGE

MODEL NUMBER

PAGE

V120RA8

9-89

VSZAl

9-96

V6SZA05

9-97

V150RAS

9-89

VSZA2

9-96

V68ZA2

9-97

V80RA8

9-89

V12ZA05

9-96

V68ZA3

9-97

V200RA8

9-89

V12ZAl

9-96

V6SZA10

9-97

V220RA8

9-89

V12ZA2

9-96

V82ZA05

9-97

V240RA8

9-89

V18ZA05

9-96

V82ZA2

9-97

V270RA8

9-89

V18ZAl

9-96

V82ZA4

9-97

V360RA8

9-89

V18ZA2

9-96

V82ZA12

9-97

V390RAS

9-89

V18ZA3

9-96

Vl00ZA05

9-97

V430RA8

9-89

V18ZA40

9-96

Vl00ZA3

9-97

V18RA16

9-90

V22ZA05

9-96

Vl00ZA4

9-97

V22RA16

9-90

V22ZAl

9-96

Vl00ZA15

9-97
9-97

V27RA16

9-90

V22ZA2

9-96

V120ZA05

V33RA16

9-90

V22ZA3

9-96

V120ZAl

9-97

V39RA16

9-90

V24ZA50

9-96

V120ZA4

9-97

V47RA16

9-90

V27ZA05

9-96

V120ZA6

9-97

V56RA16

9-90

V27ZAl

9-96

Vl50ZA05

9-97

V68RA16

9-90

V27ZA2

9-96

Vl50ZAl

9-97

V82RA16

9-90

V27ZA4

9-96

Vl50ZA5

9-97

Vl00RA16

9-90

V27ZA60

9-96

V150ZA10

9-97

V120RA16

9-90

V33ZA05

9-96

V180ZA05

9-97

V150RA16

9-90

V33ZAl

9-96

V180ZAl

9-97

V180RA16

9-90

V33ZA2

9-96

V180ZA5

9-97

V200RA16

9-90

V33ZA5

9-96

Vl80ZA10

9-97

V220RA16

9-90

V33ZA70

9-96

V220ZA05

9-97

V240RA16

9-90

V26ZA80

9-96

V270ZA05

9-97

V270RA16

9-90

V39ZA05

9-96

V330ZA05

9-97

V360RA16

9-90

V39ZAl

9-96

V390ZA05

9-97

V390RA16

9-90

V39ZA3

9-96

V430ZA05

9-97

V430RA16

9-90

V39ZA6

9-96

V470ZA05

9-97

V24RA22

9-90

V47ZA05

9-97

V680ZA05

9-97

V36RA22

9-90

V47ZAl

9-97

V750ZA05

9-97

V200RA22

9-90

V47ZA3

9-97

V910ZA05

9-97

V240RA22

9-90

V47ZA7

9-97

V270RA22

9-90

V56ZA05

9-97

V390RA22

9-90

V56ZA2

9-91

V430RA22

9-90

V56ZA3

9-97

V8ZA05

9-96

V56ZA8

9-97

viii

Table of Contents

1. VOLTAGE TRANSIENTS - AN OVERVIEW

1.1

Repeatable Transients ...................................................................... 1-1

1.2

Random Transients ......................................................................... 1-4

1.3

Transients on AC Power Lines ................................................................ 1-5

1.4

Telecommunication Line Transients ............................................................ 1-7

1.5

Automobile Transients ....................................................................... 1-7

1.6

Effects of Voltage Transients .................................................................. 1-7

1.7

Transient Detection ........................................................................ 1-10

1.S

Previous and Future Surge Recordings ........................................................ 1-10

1.9

Transient Testing and Standards .............................................................. 1-11

2. TRANSIENT SUPPRESSION - DEVICES AND PRINCIPLES
2.1

Transient Suppression Devices ................................................................2-1

2.2

Transient Suppressors Compared ..............................................................2-5

2.3

Comparison of Zener Diode and Varistor Transient Suppressors ...................................... 2-8

2.4

Proof Tests ..............................................................................2-12

2.5

Update on New Devices: Low Voltage and High Energy ........................................... 2-13

3. HARRIS VARISTORS - BASIC PROPERTIES, TERMINOLOGY AND THEORY
3.1

What is a Varistor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3-1

3.2

Physical Properties. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3-2

3.3

Varistor Construction ........................................................................3-5

3.4

Electrical Characterization ...................................................................3-8

3.5

Varistor Terminology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 3-13

4. DESIGNING WITH HARRIS VARISTORS
4.1

Selecting the Varistor .......................................................................4-1

4.2

Failure Modes and Varistor Protection ......................................................... .4-8

4.3

Series and Parallel Operation of Varistors ...................................................... 4-11

4.4

Applications ............................................................................. 4-12

ix

Table of Contents (Continued)
5. SUPPRESSION - TELECOMMUNICATION SYSTEMS

5.1

Introduction ...............................................................................5·1

5.2

System Transients ..........................................................................5-1

5.3

Lightning - Induced Transients ................................................................ 5-1

5.4

Calculations of Cable Transients ............................................................... 5-2

5.5

Power System - Induced Transients ............................................................ 5-4

5.6

Protectors - Voltage Transient Suppressors ......................................................5-5

5.7

Power Line Transient. ...................................................................... 5-7

5.8

Relay Contact Protection ..................................... " ............................. 5-7

5.9

SURGECTOR Transient Surge Suppressor ......................................................5-7

5.10 SURGECTOR Operation .....................................................................5-8
5.11 SURGECTOR Types ........................................................................5-8
5.12 SURGECTOR Performance Characteristics ...................................................... 5-9
5.13 SURGECTOR Nomenclature, Packages and Shipping ............................................ 5-10
5.14 SURGECTOR Applications .................................................................. 5-11
6. SUPPRESSION - AUTOMOTIVE TRANSIENTS

6.1

Transient Environment ......................................................................6-1

6.2

Varistor Application. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6-2

7. VARISTOR TESTING
7.1

Introduction ...............................................................................7-1

7.2

Test Objectives ............................................................................7-1

7.3

Measurement of Varistor Characteristics ........................................................7-2

7.4

Varistor Rating Assurance Tests ...............................................................7-9

7.5

Mechanical and Environmental Testing of Varistors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7-11

7.6

Equipment for Varistor Electrical Testing ....................................................... 7-12

7.7

Test Waves and Standards ............................ , .. '" ....•.......................... 7-14

8. VARISTOR REUABILITY

8.1

Introduction ..............................................................................8-1

8.2

AC Bias Reliability ........................................................................ 8-12

8.3

DC Bias Reliability........................................................................ 8-14

8.4

Pulse Energy Capability ................................................................... 8-16

8.5

Mechanical Reliability and Integrity ........................................................... 8-19

8.6

Environmental and Storage Reliability ................. " ...................................... 8-19

8.7

Radiation Hardness....................................................................... 8-21

8.8

Safety ..................................................................................8-23

x

Table of Contents (Continued)
9. VARISTOR PRODUCTS
9.1

Introduction ..............................................................................9-1

9.2

Concepts of Transient Voltage Protection ....................................................... 9·3

9.3

Speed of Response. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9·3

9.4

Varistor Safety Precautions ..................................................................9-4

9.5

How to Select a Varistor ............................................. : . . . . . . . . . . . . . . . . . . . . .. 9·6

9.6

How to Connect a Varistor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9-8

9.7

Electrical Connections ..................................................................... 9-8
AS Series· High Energy Metal Oxide Disc Varistors .............................................. 9-11
BAfBB Series - Industrial High Energy Metal Oxide Varistors ....................................... 9-22
CA Series· Industrial High Energy Metal Oxide Varistors .......................................... 9-33
CH Series· Surface Mount Metal Oxide Varistors ................................................ 9-38
CP Series· Connector Pin Metal Oxide Varistors ................................................. 9-42
CS Series· Connector Pin Metal·Oxide Varistors ................................................. 9-47
OAfDB Series· Industrial High Energy Metal Oxide Varistors ....................................... 9-50
HA Series· Industrial High Energy Metal Oxide Varistors .......................................... 9-54
LA Series· Radial Lead Metal Oxide Varistors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9-58
·C" III Series ·Radial Lead Metal-Oxide Varistors for the TVSS Environment. ........................... 9-26
MA Series· Axial Lead Metal Oxide Varistors ................................................... 9-66
ML Series· Multilayer Transient Surface Mount Surge Suppressors .................................. 9-71
AUML Series· Multilayer Transient Surface Mount Surge Suppressors ................................ 9-14
NA Series • Industrial High-Energy Metal·Oxide Square Varistors .................................... 9-79
PA Series· Base Mount Metal Oxide Varistors .................................................. 9-83
RA Series· Low Profile Radial Lead Metal Oxide Varistors ......................................... 9-87
ZA Series· Radial Lead Metal Oxide Varistors .................................................. 9-95

10. SURGECTOR PRODUCTS
SGT03U13, SGT06U13, SGT23U13- Unidirectional Transient Surge Suppressors .......................... 10-3
SGTl OSlO,' SGT27S1 0 • Gate Controlled Unidirectional Transient Surge Suppressors ....................... 10-6
SGT21B13, SGT21B13A, SGT22B13, SGT22B13A, SGT23B13, SGT23B13A,
SGT27B13, SGT27B13A, SGT27B13B· Bidirectional Transient Surge Suppressors ........................ 10-10
SGT23B27, SGT27B27, SGT27B27A, SGT27B27B· Bidirectional Transient Surge Suppressors .............. 10-14
SGT27S23 - Gate Controlled Unidirectional Transient Surge Suppressor ................................. 10-18

11. PROTECTION CIRCUITS
SP710

Protected Power Switch with Transient Suppression .......................................... 11-3

SP720

Electronic Protection Array for ESD and Overvoltage Protection (for 14 Inputs) ..................... 11-6

SP721

Electronic Protection Array for ESD and Overvoltage Protection (for 16 Inputs) .................... 11-11

TB320

SP720/SP721 CMOS Protection Model and Other Data...................................... 11-16

HIP1090

Protected High Side Power Switch with Transient Suppression ................................ 11-21

xi

Table of Contents

(Continued)

12. APPLICATION NOTES
AN8820

Recommendations For Soldering Terminal Leads to MOV Varistor Discs .......................... 12-3

AN9108

Harris Multilayer Surface Mount Surge Suppressors .......................................... 12-5

AN9211

Soldering Recommendations for Surface Mount Metal Oxide Varistors
and Multilayer Transient Voltage Suppressors .............................................. 12-15

AN9304

ESD and Transient Protection Using the SP720 ............................................ 12·22

AN9306

The New 'C" III Series of Metal Oxide Varistors ............................................ 12-27

AN9307

The Connector Pin Varistor for Transient Voltage Protection in Connectors ....................... 12-32

AN9308

Voltage Transients and Their Suppression ................................................ 12-39

AN931 0

Surge Suppression Technologies Advantages and Disadvantages
(MOVs, SADs, Gas Tubes, Filters and Transformers) ........................................ 12-44

AN9311

The ABCs of MOVs .................................................................. 12-50

AN9312

Suppression of Transients in an Automotive Environment. .................................... 12-54

13. HIGH RELIABILITY SERIES
Introduction .................................................................................. 13-1
13.1 DESC QPL .............................................................................. 13-2
13.2 DESC Source Controlled Drawings ........................................................... 13-3
13.3 Harris High ReliabilityTX Equivalents ......................................................... 13-5
13.4 Custom Types ......................................................................... "

13-6

13.5 Radiation Hardness........................................................................ 13-7
14. HOW TO USE HARRIS ANSWER FAX
15. SALES OFFICES
16. INDEX

xii

1
VOLTAGE TRANSIENTS - AN OVERVIEW
To treat any problem, the scope of the problem must first be established. This chapter is an overview of the sources and
nature of transient overvoltages, the problems they can cause and the equipment for testing and monitoring them.
Transients in electrical circuits result from the sudden release of previously stored energy. This energy can be stored
within the circuit and released by a voluntary or controlled switching action or it can be stored outside the circuit and be
injected or coupled into the circuit of interest by some action beyond the control of the circuit designer.
Transients may occur either in repeatable fashion or as random impulses. Repeatable transients, such as commutation
voltage spikes, inductive load switching, etc., are more easily observed, defined and suppressed. Random transients are
more elusive. They occur at unpredictable times, at remote locations, and require installation of monitoring instruments to
detect their occurrence. In fact, a direct corollary of Murphy's law states that the best transient suppressor is a transient
monitor! However, enough experience has been accumulated to provide reasonable guidelines of the transient
environments in low voltage ac power circuits,l-2 telecommunications equipment3 and automotive electrical systems. 4
Effective transient overvoltage protection requires that the impulse energy be dissipated in the added suppressor at a
voltage low enough to ensure the survival of circuit components. The following sections will discuss in detail the two
categories of transients, how they occur, their effects and their detection.

1.1 REPEATABLE TRANSIENTS
A sudden change in the electrical conditions of any circuit will cause a transient voltage to be generated from the energy
stored in circuit inductance and capacitance. The rate of change in current (dildt) in an inductor (L) will generate a
voltage equal to -L dildt, and it will be of a polarity that causes current to continue flowing in the same direction.
It is this effect that accounts for most switching-induced transient overvoltages. It occurs as commutating spikes in
power conversion circuits, when switching loads and under fault conditions. The effect is brief, since the source is limited
to the energy stored in the inductance (YlLi2), and it is generally dissipated at a high instantaneous power (Energy =power
x time). But the simple effect of one switching operation can be repeated several times during a switching sequence
(consider arcing in the contact gap of a switch), so that cumulative effects can be significant.

1.1.1 Energizing the Transformer Primary
When a transformer is energized at the peak of the supply voltage, the coupling of this voltage step function to the stray
capacitance and inductance of the secondary winding can generate an oscillatory transient voltage with a peak amplitude
up to twice the normal peak secondary voltage. (Figure 1.1)
Subsequent oscillations depend on the Land C parameters of the circuit. Another important point to remember is that
the secondary side will be part of a capacitive divider network in series with the transformer interwinding capacitance
(C s)' This capacitively coupled voltage spike has no direct relationship to the turns ratio of the transformer, so that it is
conceivable that the secondary circuit can see a substantial fraction of the peak applied primary voltage.

1-1

LINE

VOL~:G~

1\

v.::\/
t-CLOSED

SECONDARY
VOLTAGE

Vs
P~

LOAD

Figure 1.1 - Voltage Transient Caused by Energizing Transformer Primary
1.1.2 De-Energizing the Transformer Primary
The opening of the primary circuit of a transformer generates extreme voltage transients, especially if the transformer
drives a high impedance load. Transients in excess of ten times normal voltage have been observed across power
semiconductors when this type of switching occurs.
Interrupting the transformer magnetizing current, and the resulting collapse of the magnetic flux in the core, couples a
high voltage transient into the transformer secondary winding, as shown in Figure 1.2.

OPENING
. SWITCH

OJ
VOLTAGE
TRANSIENT
LOAD

Figure 1.2 - Voltage Transient Caused by Interruption of Transformer Magnetizing Current
Unless a low-impedance discharge path is provided, this burst of transient energy appears across the load. If this load is a
semiconductor device or capacitor with limited voltage capabilities, that component may fail. The transients produced by
interrupting the magnetizing current are usually quite severe. For example, the stored energy in the magnetizing field of a
150kVA transformer can be 9J.

1-2

1.1.3 Fault with Inductive Power Source
If a short develops on any power system, devices parallel to the load may be destroyed as the fuse clears.

,\1//

L

VSUPPLY

I

I

I'll'

P(-

OTHER
LOAD

j

Figure 1.3 - Voltage Transient Cause by Fuse Blowing During Power Fault

When the fuse or circuit breaker of Figure 1.3 opens, it interrupts the fault current, causing the slightly inductive power
source to generate a high voltage (-L di/dt), high energy (!hLP) transient across any parallel devices. Suddenly
interrupting a high current load will have a similar effect.

1.1.4 Switch Arcing

SOLID-STATE
EQUIPMENT

Figure 1.4 - Voltage Transients Caused by Switch Arcing
When current in an inductive circuit, such as a relay coil or a filter reactor, is interrupted by a contractor, the inductance
tries to maintain its current by charging the stray capacitance. Similar action can take place during a closing sequence if the
contacts bounce open after the initial closing Figure 1.4. The high initial charging current will oscillate in the inductance
and capacitance at a high frequency. When the voltage at the contact rises, breakdown of the gap is possible since the distance is still very small during the opening motion of the contact. The contact arc will clear at the current zero of the oscillation but it will restrike as the contact voltage rises again. As the contacts are moving farther apart, each restrike must occur
at a higher and higher voltage until the contact succeeds in interrupting the current.
This restrike and escalation effect is particularly apparent in Figure 1.5, where a switch opens a relay coil of 1H, having
about O.OOlpF of distributed (stray) capacitance in the winding. Starting with an initial de current of lOOmA, the circuit
produces hundreds of restrikes (hence, the "white" band on the oscillogram) at high repetition rate, until the circuit clears,
but not before having reached a peak of 3kV in contrast to the initial 125V in the circuit.

1-3

+

0-

HORIZONTAL-~ 500JlS/div.
VERTICAL -V, 1.0kV/div.

Figure 1.5 - Voltage Escalation During Restrikes
Electromechanical contacts generate transients which they generally can survive. However, in the example just
discussed, the 2.5ms long sequence of restrikes and attendant high current may be damaging to the contacts. Also, the
transients injected into the power system during the restrike can be damaging to other loads.
In an attempt to eliminate electromechanical switches and their arcing problem, solid-state switches are recommended
with good reason! However, if these switches are applied without discrimination in inductive circuits, the very
effectiveness of the interruption can lead the solid-state switch to "commit suicide" by generating high transients.
In the example of Figure 1.6, the transistor used for switching 400mA in a 70mH solenoid is exposed to 420V spikes,
although the circuit voltage is only 150V.
150 VDC 0 -_ _- - - ,

=

50 ms/DIVISION

Figure 1.6 - Transistor Switching Transient
Whenever possible, a system should be examined for potential sources of transient overvoltage so they can be
eliminated at the source, for one source can affect many components. If the sources are many (or unidentifiable) and the
susceptible components few, it may be more practical then to apply suppression at the components.

1.2 RANDOM TRANSIENTS
Frequently, transient problems arise from the power source feeding the circuit. These transients create the most
consternation because it is difficult to define their amplitude, duration and energy content. The transients are generally
caused by switching parallel loads on the same branch of a distribution system, although they also can be caused by
lightning. Communication lines, such as alarm and telephone systems, are also affected by lightning and power system
fauIts.
To deal with random transients, a statistical approach has been taken to identify the nature ofline overvoltages. While
recordings of transients have been made, one cannot state that on a specific system there is an "X" probability of
encountering a transient voltage of"Y" amplitude. Therefore, one is limited to quoting an "average" situation, while being
well aware that large deviations from this average can occur, depending on the characteristics ofthe specific system.
In the following sections, the recorded experiences of three types of systems will be described. These are: 1) ac power
lines (up to 1000V); 2) telecommunication systems; and 3) automotive systems.

1-4

1.3 TRANSIENTS ON AC POWER LINES
Data collected from various sources has provided the basis for this guide to transient overvoltages. 1,5,6.7,8

1.3.1 Amplitude and Frequency of Occurrence
The amplitude of transient recordings covers the range from harmless values just above normal voltage to several
kilovolts. For 120V ac lines, flashover of the typical wiring spacing produces an upper limit between 6 and SkY.
Ironically, the better the wiring practices, the higher the flashover, allowing higher transients to exist in the wiring system.
Studies of the frequency of occurrence and amplitude agree on an upper limit and a relative frequency of occurrence.
Figure 1.7 shows frequency as a function of amplitude. Experience indicates that devices with less than 2kV withstand
capability will have poor service life in the unprotected residential environment. Prudent design will aim for 3kV
capability, although, where safety is of the utmost concern, designing for 6kV can cope with these rare but possible
occurrences.

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(Courtesy of L. Regez, Landis & Gyr., Zug,
Switzerland'!
kV

- - - U.S. composite curve .

(120V) Service

PEAK VALUE OF VOLTAGE TRANSIENT

Figure 1.7 - Frequency of Occurrence of Transient Overvoltages in 220V and 120V Systems
For systems of higher voltages (2201240V, 4S0V), limited data is available for U.S. systems. However, the curves of
Figure 1.S indicate the difference between the two classes, 120V and 220V systems, is smaller than the differences within
each class. 8 One can conclude that the amplitude of the transient depends more upon the amount of externally coupled
energy and the system impedance than upon the system voltage.
For internal switching transients in the power system, Figure 1.S shows the relationship (computed and measured)
between system voltage and transient peaks. 8 Clearly, there is no direct linear increase ofthe transient amplitude as the
system voltage is increased.

1-5

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=time to half value
of peak

O~

_ _ __ L_ _ _ _L -_ _ _
100

200

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_ _ _ _ _ _ ________ J

300

~

400

500

RATED VOLTAGE OF DISTRIBUTION SYSTEM (VOLTS)

Figure 1.8 - Switching Voltage Transients as a Function of the System Voltage for Three Values
of the Transient Tail (Time to Half-Value)
(Data Courtesy of L Regez. Landis & Gyr" Zug. Switzerland)

Some indication of the uncertainty concerning the expected transient level can be found in the industrial practice of
choosing semiconductor ratings. Most industrial users of power semiconductors choose semiconductor voltage ratings
from 2.0 to 2.5 times the applied peak steady-state voltage, in conjunction with rudimentary transient suppression, in
order to ensure long-term reliability. Whether or not this ratio is realistically related to actual transient levels has not been
established; the safety factor is simply chosen by experience. While it is dangerous to argue against successful experience,
there are enough cases where this rule of thumb is insufficient and thus a more exact approach is justified. Another
objection to the indiscriminate rule of thumb is economic. Specifying 2.5 times the peak system voltage results in a high
price penalty for these components. It is normally unrealistic and uneconomical to specify semiconductors that should
withstand transients without protection. The optimum situation is a combination of low cost transient protection
combined with lower cost semiconductors having lower voltage ratings.

1.3.2 Duration, Waveform and Source Impedance
There is a lack of definitive data on the duration, waveform and source impedance of transient overvoltages in ac power
circuits. These three parameters are important for estimating the energy that a transient can deliver to a suppressor. It is
desirable to have a means of simulating the environment through a model of the transient overvoltage pulse. Suggestions
have been made to use standard impulses initially developed for other applications. For instance, the classical 1.2 x SOps
unidirectional voltage impulse specified in high voltage systems has been proposed.9 Also the repetitive burst of 1.5 MHz
oscillations ("SWC") specified for low-voltage and control systems exposed to transients induced by high-voltage
disconnect switches in utility switch yards is another suggestion. lo
Working Groups ofthe IEEE and the International Electrotechnical Commission have developed standard test waves
and source impedance definitions. These efforts are aiming at moving away from a concept whereby one should duplicate
environmental conditions and towards a concept of one standard wave or a few standard waves arbitrarily specified. The
justifications are that equipments built to meet such standards have had satisfactory field experience and provide a relative
standard against which different levels of protection can be compared. A condition for acceptance of these standard waves
is that they be easy to produce in the laboratory.l1 This is the central idea ofthe TCL (Transient Control Level) concept

1-6

which is currently being proposed to users and manufacturers in the electronics industry. Acceptance of this concept will
increase the ability to test and evaluate the reliability of devices and systems at acceptable cost.

1.4 TELECOMMUNICATION LINE TRANSIENTS
Transient overvoltages occurring in telephone lines can usually be traced to two main sources: lightning and 50/60 Hz
power lines. Lightning overvoltage is caused by a strike to the conductor of an open wire system or to the shield of a
telephone cable. Most modern telephone lines are contained in shielded cables. When lighthing or other currents flow on
the shield of a cable, voltages are induced between the internal conductors and the shield. 12 The magnitudes of the induced
voltages depend on the resistance of the shield material, openings in its construction, and on the dielectric characteristics
and surge impedance of the cable.
The close proximity of telephone cables and power distribution systems, often sharing right-ot~way-poles and even
ground wires, is a source of transient overvoltages for the telephone system. Overvoltages can arise from physical contact
of falling wires, electromagnetic induction, and ground potential rise. Chapter 5 of this manual presents a detailed
discussion of lightning-induced and power system-induced transients.

1.5 AUTOMOBILE TRANSIENTS
Four principal types of voltage transients are encountered in an automobile. These are "load dump," alternator field
decay, inductive switching and mutual coupling. 4 In addition, cold morning 'jump starts" with 24V batteries occur in
some areas.
The load dump transient is the most severe and occurs when the alternator current loading is abruptly reduced. The
most demanding case is often initiated by the disconnection of a partially discharged battery due to defective terminal
connections. Transient voltages have been reported over lOOV lasting up to 500ms with energy levels in the range of tens
to hundreds of joules.
Switching of inductive loads, such as motors and solenoids, will create negative polarity transient voltages with a
smaller positive excursion. The voltage waveform has been observed to rise to a level of -21OV and +80V and last as long
as 320J.lS. The impedance to the transient is unknown, leading some designers to test with very low impedance, resulting in
the use of more expensive components than necessary.
The alternator field decay transient is essentially an inductive load switching transient. When the ignition switch is
turned off, the decay ofthe alternator field produces a negative voltage spike, whose amplitude is dependent on the voltage
regulator cycle and load. It varies between -40V to -lOOV and can last 200ms.
Other unexplained transients have been recorded with peaks of 600V upon engine shutdown. Furthermore, removal of
regulation devices, particularly the battery, will raise normally innocuous effects to dangerous levels. For example,
ignition pulses up to 75V and 90J.lS in duration have been observed with the battery disconnected.
Chapter 6 provides a comprehensive review of automotive transients and practical suppression techniques to protect
automotive electronics.

1.6 EFFECTS OF VOLTAGE TRANSIENTS
1.6.1 Effects on Semiconductors
Most semiconductor devices are intolerant of voltage transients in excess of their voltage ratings. Even such a
short-lived transient as a few microseconds can cause the semiconductor to fail catastrophically or may degrade it so as to
shorten its useful life.
Frequently, damage occurs when a high reverse voltage is applied to a non-conducting PN junction. The junction may
avalanche at a small point due to the non-uniformity of the electric field. Also, excess leakage current can occur across the
passivated junction between the terminations on the pellet surface. The current can create a low resistance channel that

1-7

~

w

:::II:

w

~

degrades the junction blocking voltage capability below the applied steady-state voltage. In the avalanche case, thermal
runaway can occur because of localized heating building up to cause a melt-through which destroys the junction.
If the base-emitter junction of a transistor is repetitively "avalanched" or "zenered" by a reverse pulse, the forward
current gain may be degraded. The triggering sensitivity of a thyristor will be reduced in the same manner by "zenering"
the gate-cathode junction. Thyristors can also be damaged if turned on by a high voltage spike (forward breakover) under
bias conditions that allow a rate of current increase (di/dt) beyond device capability. This will occur in virtually all
practical circuits because the discharge of the RC dvI dt protection circuits will exceed device capability for dil dt and
destroy the thyristor.

1.6.2 Effects on Electromechanical Contacts
The high voltage generated by breaking current to an inductor with a mechanical switch will ultimately cause pitting,
welding, material transfer, or erosion of the contacts. The nature of ultimate failure of the contacts depends upon such
factors as the type of metal used, rate of opening, contact bounce, atmosphere, temperature, steady-state and inrush
currents, and ac or dc operation. Perhaps most important is the amount of energy dissipated in each operation of the
contacts.
The actual breaking of current by a set of contacts is a complex operation. The ultimate break occurs at a microscopic
bridge of metal which, due to the inductive load, is forced to carry nearly all the original steady-state current. Ohmic
heating of this bridge causes it to form a plasma, which will conduct current between the contacts when supplied with a
current and voltage above a certain threshold. The inductor, of course, is more than happy to supply adequate voltage
(EL =-L dil dt). As the contacts separate and the current decreases, a threshold is reached, and the current stops abruptly
("chopping"). Inductor current then charges stray capacitances up to the breakdown voltage of the atmosphere between
the contacts. (For air, this occurs at 30kVlin.) The capacitance discharges and recharges repeatedly until all the energy is
dissipated. This arc causes sufficient contact heating to melt, oxidize, or "burn" the metal, and when the contacts close
again, the contacts may form a poorer connection. If they "bounce," or are closed soon after arcing, the contacts may be
sufficiently molten to weld closed. Welding can also occur as a result of high inrush currents passing through the initially
formed bridges upon closing.
Good suppression techniques can significantly reduce the amount of energy dissipated at the contacts, with a
proportional increase in operating life. Suppression can also reduce the noise generated by this arcing. Voltage-limiting
devices are particularly suited to preventing the noisy high-voltage "showering" arc described above and illustrated in
Section 1.1.4.

1.6.3 Effects on Insulation
Transient overvoltages can cause breakdown of insulation, resulting in either a temporary disturbance of device
operation or instantaneous failure. The insulating level in the former case will be weakened leading to premature failure.
The severity of the breakdown varies with the type of insulation - air, liquid, or solid. The first two tend to be
self-healing, while breakdown of solid insulation (generally organic materials) is generally a permanent condition.
Air clearances between metal parts in electrical devices and power wiring constitute air gaps, which behave according to
the usual physics of gap breakdown (pressure, humidity, shape of electrodes, spacing). The International Electrotechnical
Commission Working Group on Low Voltage Insulation Coordination has developed a table listing the minimum clearances
in air for optimum and worst case electric field conditions existing between electrodes. 13 Breakdown of the clearance
between metal parts can be viewed as a form of protection, limiting the overvoltage on the rest of the circuit. However, this
protection is dependent upon the likelihood of ac line current that may follow during the arc breakdown. Normally, powerfollow current should cause the system fuse or breaker to function. If the power-follow current heat is limited by circuit
impedance, then.the system fusing may not operate. In that case, sufficient heat could be generated to cause a fire. Experience with power wiring has shown that metal clearances can flash-over harmlessly under transient voltage conditions, and
power-follow problems are rare, but can occur.
In liquid dielectrics, an impulse breakdown not followed by a high current is normally harmless. However, this type of
breakdown is of limited interest in low-voltage systems, where liquid insulation systems are seldom used, except in
combination with some degree of solid insulation.

1-8

Breakdown of solid insulation generally results in local carbonization of an organic material. Inorganic insulation
materials are generally mechanically and permanently damaged. When no power-follow current takes place, the system
can recover and continue operating. However, the degraded insulating characteristic of the material leads to breakdown at
progressively lower levels until a mild overvoltage, even within ac line overvoltage tolerances, brings about the ultimate
permanent short circuit. Since the final failure can occur when no transients are present, the real cause of the problem may
be concealed.
Breakdown along surfaces of insulation is the concern of "creepage" specifications. The working group of IEC cited
above is also generating recommendations on creepage distances. The behavior of the system where creepage is concerned
is less predictable than is breakdown of insulation in the bulk because the environment (dust, humidity) will determine the
withstand capability of the creepage surface.
When considering the withstand capabilities of any insulation system, two fundamental facts must be remembered. The
first is that breakdown of insulation is not instantaneous but is governed by the statistics of avalanche ionization. Hence
there is a "volt-time" characteristic, which challenges the designer to coordinate protection systems as a function of the
impinging waveshape. The second is that the distribution of voltage across insulation is rarely linear. For example, a steep
wave front produces a piling up of voltage in the first few turns of a motor winding, often with reflections inside the
winding. Also, the breakdown in the gap between the electrodes, initiating at the surface, is considerably dependent upon
the overall field geometry, as well as on macroscopic surface conditions.

1.6.4 Effects on Power Consumption
As a result of the increasing emphasis on energy conservation, a number of transient voltage suppression devices have
been offered for sale as energy savers. The premise seems to be that transient overvoltages would cause degradation of
electrical equipment leading to increased losses and thus to a waste of energy. No convincing proof has been offered to
support this claim, and injunctions against making such claims have been obtained in several states. 14

1.6.5 Noise Generation
With sensitive logic gates gaining popularity, noise problems are frequent, especially in environments with
electromechanical devices. Noise can upset automatic manufacturing equipment, medical equipment, computers, alarms
and thyristor-controlled machinery. Such disruption can cause loss of product, time, money, and even human life.
Noise enters a system either directly on wires or grounds connected to the source or through coupling to adjacent wires.
Noise problems are dealt with by suppression at the source, at the receiver, or by isolation. Noise is induced when stray
capacitance or mutual inductance links the susceptible system to the noise-generating system. The amplitude of the
induced noise is then related to the rate-of-change of either the current or the voltage of the noise source. The
low-frequency components of the induced noise (which are hardest to filter out) are a result of the amplitude of the
original transient impulses.
Frequently, the source of noise is the arcing of contacts breaking current through an inductor, such as a relay coil. A
low-current, high-voltage arc creates a series of brief discharges of a damped oscillatory nature, occurring at kHz to MHz
frequencies with amplitudes offrom 300 to several thousand volts. These pulses and their reflections from loads and line
discontinuities travel along the power wires, easily inducing noise in adjacent wiring. This interference is best eliminated
by preventing it at the source (the inductance) with voltage-limiting devices such as varistors.

1.6.6 Rate of Rise vs. Amplitude
Interference coupled into electronic systems, as opposed to damage, is most often associated with the rate of rise of the
interfering signal rather than its peak amplitude. Consequently, low-amplitude fast-rise interference which is dealt only by
the capacitance of a varistor until the clamping level is reached by the impinging interference may still be a problem with
the circuit if attempts are made to suppress it with a retrofit varistor at the location of the victim. A much more effective
cure would be to install the appropriate varistor near the source of the offending surge, so that the interference radiated or
coupled by the surge would be confined to the immediate vicinity of the offending source.

1-9

1.7 TRANSIENT DETECTION
Voltage transients are brief and unpredictable. These two characteristics make it difficult to detect and measure them.
Even transients described earlier in this chapter as "repeatable" are subject to variations resulting from the timing of the
switching operation, the erratic bouncing of contacts, and other random combinations.
The transient detector par excellence is the high-frequency storage oscilloscope, but its cost limits its availability. Custom
systems have been built to monitor transients on location,IS. 16 but cost has been a limiting factor in this method of detection
as well. A conventional oscilloscope with high-frequency response can be used as a monitor if it is provided with singlesweep controls for monitoring transients occurring at random times but at relatively low frequent rates. The operator sets the
trigger controls at some threshold level in single-sweep mode and watches the "ready" light on the oscilloscope panel while
a camera with open shutter records the screen display. The film is pulled after the operator notices that sweep occurred and,
thus, a record is obtained. While not very efficient for extensive monitoring, this method is very effective for short-term panics - the most frequent situation when transients are suspected. Digital storage oscilloscopes with automatic data transfer to
a magnetic disc are now available for unattended monitoring.
In recent years, leading oscilloscope manufacturers have developed improved versions of storage oscilloscopes and
high-frequency oscilloscopes, and most laboratories now are equipped with one or another. The experienced engineer can
put them to work and obtain satisfactory recordings by the technique described above, using normal safeguards against
erroneous recordings (check on noise background, stray ground currents, radiation of noise into preamplifier circuits, high
frequency response limitations in differential mode, etc.).
A wide variety of suitable analog or digital test instruments is commercially available. These allow economical
monitoring of a remote location by providing various degrees of storage (single-event recording, counting above a
threshold, digital memory for playback, etc.).
Trade magazines and engineering papers have also described a number of homemade detectors. While these are
undoubtedly performing to the satisfaction of their creators, one can question the economic wisdom of investing time and
engineering resources to duplicate, debug, validate and calibrate a homemade device when so many commercial units
offering well demonstrated and credible performance are available.

1.8 PREVIOUS AND FUTURE SURGE RECORDINGS
The supporting data cited in the IEEE Guide on Surge Voltages, ANSI/IEEE C62-41-1980, are based on voltage surge
recordings made in the 1962-1965 period. In that period, digital instrumentation for surge monitoring was not as readily
available as it is now, and, most significantly, the proliferation of surge protective devices, such as metal oxide varistors,
had not reached the present level.
Measurements, limited to voltage, were conducted with oscilloscope/camera systems or with peak-recording
instruments. Voltages were generally recorded between the line(s) and the neutral of a single-phase or polyphase power
system. No measurements had been reported as neutral-to-ground; some may have been between line and ground. Of
course, that distinction is moot for measurements made at the service entrance where neutral and ground are bonded.
An estimate ofthe number oflow-voltage surge protective devices such as varistors used in the United States since 1972
on ac power circuits is in the order of 500 million. An undefined but substantial portion of that number is installed in
permanently connected equipment. Therefore, it is now very likely that a new limitation exists in the recording of voltage
surges. A surge recording instrument installed indiscriminately at a random location may have a varistor connected across
the line near the point being recorded. 17 This situation will have several implications for the recordings obtained in present
and future measurements, as contrasted to those of previous measurement campaigns.
1. Locations where voltage surges were previously identified - assuming no change in the source of surges - are now

likely to experience lower voltage surges, while current surges will occur in the newly installed protective devices.
2. Not only will the peaks ofthe observed voltages be changed, but also their waveforms will be affected by the presence
of nearby varistors as follows:
a. If a varistor is located between the source of the surge and the recording instrument, the instrument will record the
clamping voltage of the varistor. This voltage will have lower peaks but longer time to half-peak than the original
surge.

1-10

b. If the instrument is located between the source of the surge and a varistor, or if a varistor is installed in a parallel
branch circuit, the instrument will record the clamping voltage ofthe varistor, preceded by a spike corresponding
to the inductive drop in the line supplying surge current into the varistor.
c. If a varistor is connected between line and neutral with a surge impinging between line and neutral at the service
entrance, a new situation is created: the line-to-neutral voltage is indeed clamped as intended, but the inductive
drop in the neutral conductor between the point of connection of the varistor and the service entrance creates a
spike voltage between the neutral and the grounding connector at the point of connection of the varistor and
downstream points supplied by the same neutral. Because this spike will have a short duration, it will be enhanced
by the open-end transmission line effect between the neutral and grounding conductors. ls
3. The surge voltage limitation function performed by flashover of clearances is more likely to be assumed by new surge
protective devices that are constantly being added to the systems.
4. The considerations discussed in paragraphs 1,2, and 3 above will produce a significant reduction in the mean of
recorded voltage surges in a population of different locations. This reduction will continue as more and more varistors
are installed. The upper limit, however, will remain the same for locations where no varistor has yet been installed. A
sense of false security and an incorrect description of the environment might be created by attention given only to the
average of voltage surges presently recorded in power systems. Furthermore, the need for adequate surge current
handling capability of a new candidate surge suppressor might be underestimated if partial surge diversion is already
being performed by a nearby varistor. This risk will be exacerbated if an attempt is made to clamp at lower voltages by
the installation of a new protective device with a clamping voltage lower than that of the device already installed. 19

1.9 TRANSIENT TESTING AND STANDARDS
It is desirable to have test criteria and definitions that provide a common engineering language beneficial to both the
user and manufacturer of surge protective devices. Regretfully, different terms have come into use through industry
practice over the years. Testing standards have tended to proliferate as the measurement objective defines either the
characteristics of the protective device or the environment of the application.
The characteristics of each surge protection device will vary according to its basic construction. Protective devices are
diverse, being based on ionized gas breakdown, semiconductor junction breakdown, and "charge hopping" conduction.
For this reason, it seems sensible to group devices by physical category and set up pertinent standards that are suitable for
characterizing their behavior. The standards would use appropriate stress levels and measure those parameters that are
critical to ensuring proper performance.
The application environment has demanded different conditions of transient levels. Standards vary depending on
system usage, whether protection is intended for power lines, telecommunications, automotive, or aircraft, to name a few.
Each environment also has been defined with less than full precision leading to additional diversity on choice of
waveshape, amplitude and duration.
Several organizations such as ANSI/IEEE, lEe, UL, NEMA are currently developing guidelines and standards to
describe what the environment is likely to be, on the basis of accumulated recording and field experience. From this, test
specifications are being prepared20, 21, 22, 23 that will allow objectives are realistic evaluation of suppressor applications.

1-11

The Development of a Guide* on Surge Voltages in
Low-Voltage AC Power Circuits
F.D. MARTZLOFF,

FELLOW. IEEE

INTRODUCTION

Scause
URGE VOLTAGES occurring in ac power circuits can be the
of misoperation or product failure for residential as well
as industrial systems. The problem has received increased attention
in recent years because miniaturized solid state devices are more
sensitive to voltage surges (spikes and transients) than were their
predecessors.
Although surge voltage amplitudes and their frequency of
occurrence on unprotected circuits are well known, their waveshapes and energy content are less well known. On the basis of
measurements, statistics, and theoretical considerations, a practical
guide for outlining the environment for use in predicting extreme
waveshapes and energy content can nevertheless be established. A
Working Group of the Surge Protective Devices Committee has
completed such a descriptive Guide.t The Guide proposes two
waveforms, one oscillatory, the other unidirectional, depending on
the location within the power system. It also includes recommendations for source impedance or short-circuit current. While the
major purpose of the Guide is to describe the environment. a
secondary purpose is to lead toward standard tests.

~

..'".
~

0

~

~

U

~

u

1:i
i!:
a:

,..

;li
a:
~

13

'":>
a:

'"

SURGE CREST· kV

*In some locations. sparkover of clearances may limit the Qvervoltages

Fig. I.

THE ORIGINS OF SURGE VOLTAGES
Surge voltages occurring in low-voltage ac power circuits
originate from two major sources: system switching transients and
direct or indirect lightning effects on the power system. System
switching transients can be divided into transients associated with
(1) major power system switching disturbances, such as capacitor
bank switching; (2) minor switching near the point of interest, such
as an appliance turnoff in a household or the turnoff of other loads
in an individual system; (3) resonating circuits associated with
switching devices, such as thyristors; and (4) various system faults,
such as short circuits and arcing faults.
Measurements and calculations of lightning effects have been
made to yield data on what levels can be produced, even if the
exact mechanism of any particular surge is unknown. While the
data have been recorded primarily on 120,220/380, or 277/480V
systems, the general conclusions should be valid for 600V systems.
To the extent that surge voltages are produced by a discrete
amount of energy being dumped into a power system, lowimpedance, heavy industrial systems can be expected to experience
lower peaks from surge voltages than 120V residential systems, but
comparable, or greater, amounts of energy potentially available for
deposition in a surge suppressor.

10'

~

Rate of surge occurrence versus voltage level at unprotected locations.

RATE OF OCCURRENCE AND VOLTAGE LEVELS IN
UNPROTECTED CIRCUITS
The rate of occurrence of surges varies over wide limits,
depending on the particular power system. Prediction of the rate
for a particular system is always difficult and frequently impossible.
Rate is related to the level of the surges; low-level surges are more
prevalent than high-level surges.
It is essential to recognize that a surge voltage observed in a
power system can be either the driving voltage or the. voltage
limited by the sparkover of some clearance in the system. Hence,
the term unprotected circuit must be understood to be a circuit in
which no low-voltage protective device has been installed but in
which clearance sparkover will eventually limit the maximum
voltage. The distribution of surge levels, therefore, is influenced by
the surge-producing mechanisms as well as by the sparkover level
or clearances in the system. This distinction between actual driving
voltage and voltage limited by sparkover is particularly important
at the interface between outdoor equipment and indoor equipment.
Outdoor equipment has generally higher clearances, hence higher
sparkover levels: JOkV may be typical, but 20kV is possible. In
contrast, most indoor wiring devices used in 120-240V systems
have sparkover levels of about 6kV; this 6kV level, therefore, can
be selected as a typical cutoff for the occurrence of surges in indoor
power systems.

'Condensed from a paper presented at the 1979 IEEE 14th Electrical/Electronics insulation Conference, Boston, October 9-11 1979. Reprinted with permission of the
Institute of Electrical and Electronics Engineers.
tANSI/IEEE C62.41-1980 Guide on Surge Voltages in Low-Voltage AC Power Circuits.

1-12

Data collected from many sources have led to the plot shown in
Figure 1. This prediction shows with certainty only a relative
frequency of occurrence, while the absolute number of occurrences
can be described only in terms of "low exposure," "medium
exposure," or "high exposure." These exposure levels can be
defined in general terms as follows:
Low Exposure - Systems in geographical areas known for low
lightning activity, with little load switching activity.
Medium Exposure - Systems in geographical areas known
for high lightning activity, with frequent and severe switching
transients.
High Exposure - Rare but real systems supplied by long
overhead lines and subject to reflections at line ends, where the
characteristics of the installation produce high sparkover levels of
the clearances.
The two lower lines of Figure 1 have been drawn at the same
slope, since the data base shows reasonable agreement among
several sources on that slope. All lines may be truncated by
sparkover of the clearances at levels depending on the withstand
voltage of these clearances. The "high-exposure" line needs to be
recognized, but it should not be applied indiscriminately to all
systems. Such application would penalize the majority of installations, where the exposure is lower.
From the relative values of Figure I, two typical levels can be
cited for practical applications. First, the expectation 3kV transient
occurrence on a 120V circuit ranges from 0.01 to 10 per year at a
given location - a number sufficiently high to justify the
recommendation of a minimum 3kV withstand capability. Second,
the sparkover of wiring devices indicates that a 6kV withstand
capability may be sufficient to ensure device survival indoors, but a
withstand capability of IOkV, or greater, may be required
outdoors.
The voltage and current amplitudes presented in the Guide
attempt to provide for the vast majority of lightning strikes but
should not be considered as "worst case," since this concept cannot
be determined realistically. One should think in terrns of the
statistical distribution of strikes, accepting a reasonable upper limit
for most cases. Where the consequences of a failure are not
catastrophic but merely represent an annoying economic loss, it is
appropriate to make a trade-off of the cost of protection against the
likelihood offailure caused by a high but rare surge. For instance, a
manufacturer may be concerned with nation-wide failure rates,
those at the upper limits of the distribution curve, while the user of
a specific system may be concerned with a single failure occurring
at a specific location under "worst-case conditions." Rates can be
estimated for average systems, however, and even if imprecise,
they provide manufacturers and users with guidance. Of equal
importance is the observation that surges in the range of I to 2kV
are fairly common in residential circuits.
Surges occur at random times with respect to the power
frequency, and the failure mode of equipment may be affected by
the power frequency follow current. Furthermore, the timing of the
surge with respect to the power frequency may affect the level at
which failure occurs. Consequently, when the failure mode is likely
to be affected, surge testing should be done with the line voltage
applied to the test piece.

WAVESHAPE OF REPRESENTATIVE SURGE VOLTAGES

Waveshapes in Actual Occurrences
Indoor - Measurements in the field, measurements in the
laboratory, and theoretical calculations indicate that most surge
voltages in indoor low-voltage systems have oscillatory waveshapes, unlike the well-known and generally accepted unidirectional waves specified in high-voltage insulation standards. A surge
impinging on the system excites the natural resonant frequencies of
the conductor system. As a result, not only are the surges typically
oscillatory, but surges may have different amplitudes and waveshapes at different places in the system. These oscillatory frequencies
of surges range from 5kHz to more than 500kHz. A 30 to 100kHz
frequency is a realistic measure of a "typical" surge for most
residential and light industrial ac line networks.
Outdoor and Service Entrance - Surges encountered in
outdoor locations have also been recorded, some oscillatory, other
unidirectional. The "classical lightning surge" has been established
as 1.2/50ps for a voltage wave and 8120ps for a current wave, but
these waveshapes should not be construed as typical waves for
low-voltage circuits. Lightning discharges induce oscillations,
reflections, and disturbances that ultimately appear as decaying
oscillations in low-voltage systems.
Because the prime concern here is the energy associated with
these surges, the waveshape to be selected must involve greater
energy than that associated with the indoor environment. Secondary surge arresters have a long history of successful performance,
meeting the ANSI C62.l specification, as detailed below; consequently, these specifications can be adopted as a realistic representation of outdoor waveshapes.
Selection of Representative Waveshapes
The definition of a waveshape to be used as representative of the
environment is important for the design of candidate protective
devices, since unrealistic requirements, such as excessive duration
of the voltage or very low source impedance, place a high energy
requirement on the suppressor, with a resulting cost penalty to the
end user. The two requirements defined below reflect this trade-off.
Indoor - Based on measurements conducted by several
independent organizations in 120 and 240V systems, the waveshape shown in Figure 2 is reasonably representative of surge
voltages in these power circuits. Under the proposed description of
a "O.5ps - 100kHz ring wave," this waveshape rises in O.5ps, then
decays while oscillating at 100kHz, each peak being about 60% of
the preceding peak.
Outdoor - In the outdoor and service entrance environment, as
well as in locations close to the service entrance, substantial energy,
or current, is still available, in contrast to the indoor environment,
where attenuation has taken place. For these locations, the
unidirectional impulses long established for secondary arresters are
more appropriate than the oscillatory wave.
Accordingly, the recommended waveshape is 1.2I50ps for the
open-circuit voltage or voltage applied to a high-impedance
device, and 8120ps for the discharge current or current in a
low-impedance device. The numbers used to describe the impulse,
1.2/50 and 8120, are those defined in IEEE Standard 28 - ANSI

1-13

Standard C62.l; Figure 3 presents the waveshape and a graphic
description of the numbers.

--v,.
O.9V~

T = 10 .. If

= 100 kHz)

•

impedance (of the surge source or test generator) are sufficient to
calculate the short-circuit current, as well as any current fora
specified suppressor impedance.
The measurements from which Figure 1 was derived were of
voltage only. Little was known about the impedance of the circuits
upon which the measurements were made. Since then, measurements have been reported on the impedance of power systems.
Attempts were made to combine the observed 6kV open-circuit
voltage with the assumption of a parallel 500/50pH impedance.

0.1 V,.
O.5"s-

0.9 V,*

0.3 Vpk

Fig. 2.

The proposed O.S/lS - 100kHz ring wave (open-circuit voltage)

ENERGY AND SOURCE IMPEDANCE
General
The energy involved in the interaction of a power system with a
surge source and a surge suppressor will divide between the source
and the suppressor in accordance with the characteristics of the
two impedances. In a gap-type suppressor, the low impedance of
the arc after sparkover forces most of the energy to be dissipated
elsewhere: for instance, in a resistor added in series with the gap for
limiting the power-follow current. In an energy-absorber suppressor, by its very nature, a substantial share of the surge energy is
dissipated in the suppressor, but its clamping action does not
involve the power-follow energy resulting from the short-circuit
action of a gap. It is therefore essential to the effective use of
suppression devices that a realistic assumption be made about the
source impedance ofthe surge whose effects are to be duplicated.
The voltage wave shown in Figure 2 is intended to represent the
waveshape a surge source would produce across an open circuit.
The waveshape will be different when the source is connected to a
load having a lower impedance, and the degree to which it is lower
is a function of the impedance of the source.
To prevent misunderstanding, a distinction between source
impedance and surge impedance needs to be made. Surge
impedance, also called characteristic impedance, is a concept
relating the parameters of a line to the propogation of traveling
waves. For the wiring practices of the ac power circuits discussed
here, this characteristic impedance would be in the range of 150 to
3000, but because the durations of the waves being discussed (50
to 20ps) are much longer than the travel times in the wiring
systems being considered, traveling wave analyses are not useful
here.
Source impedance, defined as "the impedance presented by a
source energy to the input terminals of a device, or network"
(IEEE Standard 100), is a more useful concept here. In the
conventional Thevenin's description, the open-circuit voltage (at
the terminals of the network or test generator) and the source

TI

T1 x 1.67 = 1.21's

0.91p1!;

O.llp1c

~-+----+-----~~--~
T,

Fig. 3. Unidirectional (ANSI Standard C62.l) wavesbapes
(a) open-circuit voltage waveform (b) discharge current waveform

This combination resulted in low energy deposition capability,
which was contradicted by field experience of suppressor performance. The problem led to the proposed definition of oscillatory
waves as well as high-energy unidirectional waves, in order to
produce both the effects of an oscillatory wave and the high-energy
deposition capability.
The degree to which source impedance is important depends
largely on the type of surge suppressors that are used. The surge
suppressors must be able to withstand the current passed through
them by the surge source. A test generator of too high an
impedance may not subject the device under test to sufficient
stresses, while a generator of too Iowan impedance may subject
protective devices to unrealistically severe stresses. A test voltage
wave specified without reference to source impedance could imply

1-14

zero source impedance - one capable of producing that voltage
across any impedance, even a short circuit. That would imply an
infinite surge current, clearly an unrealistic situation.
Because of the wide range of possible source impedances and the
difficulty of selecting a specific value, three broad categories of
building locations are proposed to represent the vast majority of
locations, from those near the service entrance to those remote
from it. The source impedance of the surge increases from the
outside to locations well within the building. Open-circuit
voltages, on the other hand, show little variation within a building
because the wiring provides little attenuation. Figure 4 illustrates
the application of the three categories to the wiring of a building.
For the two most common location categories, Table 1 shows
the representative surge voltages and currents, with the waveforms
and amplitudes of the surges, and high- or low-impedance
specimen. For the discharge current shown, the last two columns
show the energy that would be deposited in a suppressor clamping
at 500V and lOOOV, typical of l20V or 240V applications,
respectively. For higher system voltages (assuming the same
current values), the energy would increase in proportion to the
clamping voltage of a suppressor suitable for that system voltage.
The values shown in Table 1 represent the maximum range and
correspond to the "medium exposure" situation of Figure l. For
less exposed systems, or when the prospect of a failure is not highly
objectionable, one could specify lower values of open-circuit
voltages with corresponding reductions in the discharge currents.
The 6kV open-circuit voltage derives from two facts: the
limiting action of wiring device sparkover and the unattenuated
propagation of voltages in unloaded systems. The 3kA discharge
current in Category B derives from experimental results: field
experience in suppressor performance and simulated lightning
tests. The two levels of discharge currents from the O.5ps - 100kHz
wave derive from the increasing impedance expected in moving
from Category B to Category A.
Location Category C is likely to be exposed to substantially
higher voltages than location Category B because the limiting
effect of sparkover is not available. The "medium exposure" rates
of Figure 1 could apply, with voltage in excess of IOkV and
discharge currents of 10kA, or more. Installing unprotected load
equipment in location Category C is not recommended; the

c

B

A

A. Outlets and Long Branch Circuits
All outlets at more than 10m (30
ttl from Category B with wires
#14-10
All outlets at mote than 20m 160
ftl from Category C with wires
#14-10

B. Major Feeders and Short Branch

Circuits
Distribution panel devices
Bus and feeder systems in
industrial plants
Heavy appliance outlets with
"short" connections to the
service entrance
lighting systems in commercial

C. Outside and Service Entrance
Service drop from pole to

building entrance
Run between meter and
distribution panel
Overhead line to detached
buildings
Underground lines to well pumps

Fig. 4.

Location categories

installation of secondary arresters, however, can provide the
necessary protection. Secondary arresters having lOkA ratings
have been applied successfully for many years in location Category
C (ANSI Standards C62.l and C62.2).

TABLE I
SURGE VOLTAGES AND CURRENTS DEEMED TO REPRESENT THE INDOOR ENVIRONMENT AND SUGGESTED FOR
CONSIDERATION IN DESIGNING PROTECTIVE SYSTEMS
Impulse
Location
Category
A. Long branch
circuits and
outlets
B. Major feeders
short branch
circuits, and
load center

Comparable
To IEC 664
Category

Waveform

Medium Exposure
Amplitude

Type
of Specimen
or Load
Circuit

Energy (Joules)
Deposited in a Suppressor(3)
With Clamping Voltage of
500V

lOOOV

(l20V System) (240V System)
II

III

O.5/1S - 100kHz
1.2/50j1s
8/20ps

0.5/1s - 100kHz

3kA

High impedance(l)
Low impedance(2)
High impedance(l)
Low impedance(2)

6kV
500A

High impedance(l)
Low impedance(2)

6kV
200A
6kV

-

-

0.8

1.6

-

-

40

80

-

-

2

4

Notes: (1) For high-impedance test specimens or load circuits, the voltage shown represents the surge voltage. In making simulation tests, use that value
for the open-circuit voltage of the test generator.
(2) For low-impedance test specimens or load circuits, the current shown represents the discharge current of the surge (not the short-circuit
current of the power system). In making simulation tests, use that current for the short-circuit current of the test generator.
(3) Other suppressors which have different clamping voltages would receive different energy levels.

1-15

REFERENCES
1. Martzloff, F.D., "The Development of a Guide on Surge Voltages in Low- Voltage A C Power Circuits," Report
81CRD047, General Electric, Schenectady, New York 1981.
-2. Greenwood, Allan, Electrical Transients in Power Systems, Wiley-Interscience, New York, 1971.
3. Bodle, D.W., A.J. Ghaze, M. Syed and R.L. Woodside, Characterization of the Electrical Environment, Toronto:
University of Toronto Press, 1970.
4. Recommended Environmental Practices for Electronic Equipment Design, Publication SAE 11211, Society of
Automotive Engineers, Warrendale, Pennsylvania.
5. Hahn, G.J. and F.D. Martzloff, "Surge Voltages in Residential and Industrial Power Circuits," IEEE Trans. PAS-89,
No.6, July-Aug. 1970, pp. 1049-1056.
6. Bull, J.H., "Voltage Spikes in L. v: Distribution Systems and Their Effects on the Use of Electronic Control
Equipment" Report No. 5254, Electrical Research Assn., Cleeve Rd., Leatherhead, Surrey, Great Britain, 1968.
7. IEEE Surge Protective Devices Committee, "Bibliography on Surge Voltages inAC Power Circuits Rated 600 Volts
or Less," IEEE Trans. PAS-89, No.6, July-Aug. 1970, pp. 1056-1061.
8. Data contributed by L. Regez (Landis & Gyr. Co., Zug, Switzerland), Swiss representative to IEC Working Group
28A on Low Voltage Insulation Coordination.
9. Surge Arresters for Alternating Current Power Circuits, ANSI Standard C62.1, IEEE Standard 28, 1974.
10. Guide for Surge Withstand Capability (SWC) Test, ANSI Standard C37.90a, 1974, IEEE Standard 472, 1974.
11. Martzloff, F.D. and F.A. Fisher, "Transient Control Level Philosophy and Implementation - The Reasoning Behind
the Philosophy," 77CHI224-SEMC, Proceedings of the 2nd Symposium on EMC, Montreux, June 1977.
12. Fisher, F.A., "A Way to Evaluate the Effects of Changing Magnetic Fields on Shielded Conductors," Report
77CRD158, General Electric, Schenectady, New York, July 1977.
--

13. "Insulation Co-ordination Within Low-Voltage Systems, including Clearances and Creepage Distances for
Equipment," IEC Report 664, 1980.
14. "Evaluation of Transient Voltage Suppressors for Saving Electric Energy, "EPRI EM-I722, February 1981.
15. Allen, George W., "Design ofPower-Line Monitoring Equipment" IEEE Trans. PAS-90, No.6, Nov-Dec. 1971, pp.
2604-2609.
16. Herzog, R., "How to Catch a Transient" Machine Design Magazine, March 1973, pp. 170-175.
17. Martzloff, F.D., Discussion of paper "Rural Alaska Electric Power Quality," IEEE Transactions on Power
Apparatus and Systems PAS-104, No.3, pp. 618-619, March 1985.
18. Martzloff, F.D. and Gauper, H.A., Surge and High Frequency Propagation in Industrial Power Lines,
85CRD087,General Electric Company, Schenectady, New York, 1985.
19. Martzloff, F.D., "Varistor versus Environment: Winning the Rematch," IEEE/PES Summer Meeting, 1985Scheduled for IEEE Transaction on Power Apparatus and System, 1986.
20. IEEE Standard Test Specifications for Gas Tube Surge-Protective Devices, ANSI/IEEE C62.31-1981.
21. IEEE Standard Test Specifications for Low-Voltage Air Gap Surge-Protective Devices (Excluding Valve and
Expulsion Type Devices), ANSI/IEEE C62.32-1981.
22. IEEE Standard Test Specifications for Varistor Surge-Protective Devices, ANSI/IEEE C62.33-1982.
23. IEEE Standard Test Specifications for Avalanche Junction Semiconductor Surge-Protective Devices, IEEE
C62.34-1984.

1-16

TV~~

------I

2

TRANSIENT SUPPRESSION - DEVICES AND PRINCIPLES
This chapter presents a brief description of available transient suppressors and their operation, and discusses how these
devices can be applied.

2.1 TRANSIENT SUPPRESSION DEVICES
There are two major categories of transient suppressors: a) those that attenuate transients, thus preventing their
propagation into the sensitive circuit; and b) those that divert transients away from sensitive loads and so limit the residual
voltages.
Attenuating a transient - that is, keeping it from propagating away from its source or keeping it from impinging on a
sensitive load - is accomplished with filters inserted in series within a circuit. The filter, generally of the low-pass type,
attenuates the transient (high frequency) and allows the signal or power flow (low-frequency) to continue undisturbed.

OCJ)

Zw

c(..J
CJ)Q.

Diverting a transient can be accomplished with a voltage-clamping type device or with a "crowbar" type device. The
designs of these two types, as well as their operation and application, are different enough to warrant a brief discussion of
each in general terms. A more detailed description will follow later in this chapter.
A voltage-clamping device is a component having a variable impedance depending on the current flowing through the
device or on the voltage across its terminal. These devices exhibit a nonlinear impedance characteristic - that is, Ohm's
law is applicable but the equation has a variable R. The variation of the impedance is monotonic; in other words, it does
not contain discontinuities in contrast to the crowbar device, which exhibits a turn-on action. The volt-ampere
characteristic of these clamping devices is somewhat time-dependent, but they do not involve a time delay as do the
sparkover of a gap or the triggering of a thyristor.
1000

"' 100 ~"'---~

~
o
>

OJ

LINEAR

co

~

IMPEDANCE'

..J

5!

10

---+--~

NON-LINEAR
IMPEDANCE
(POWER LAW)'

0.1

10
CURRENT -

100

I ' KV a

1000

AMPERES

Figure 2.1 - Voltage/Current Characteristic for a Linear 1 Ohm Resistor and Nonlinear.Varistor

With a voltage-clamping device, the circuit is unaffected by the presence of the device before and after the transient for
any steady-state voltage below the clamping level. The voltage clamping action results from the increased current drawn
through the device as the voltage tends to rise. If this current increase is greater than the voltage rise, the impedance of the
device is nonlinear (Figure 2.1). The apparent "clamping" of the voltage results from the increased voltage drop (IR) in
2-1

w-

OO
_Z

>wO::
oil.

the source impedance due to the increased current. It should be clearly understood that the device depends on the source
impedance to produce the clamping. One is seeing a voltage divider action at work, where the ratio of the divider is not
constant but changes. However, if the source impedance is very low, then the ratio is low. The suppressor cannot be
effective· with zero source impedance (Figure 2.2) and works best when the voltage divider action can be implemented.
Zs

seR
Voe

Vz:;

Zv

a) Voltage Clamping Device

b) Crowbar Device

Figure 2.2 - Division of Voltage with Variable Impedance Suppressor

Crowbar-type devices involve a switching action, either the breakdown of a gas between electrodes or the turn-on of a
thyristor. After switching on, they offer a very low impedance path which diverts the transient away from the
parallel-connected load.
These crowbar devices have two limitations. The first is their delay time, typically microseconds, which leaves the load
unprotected during the initial rise. The second limitation is that a power current from the steady-state voltage source will
follow the surge discharge (called "follow-current" or "power-follow"). In ac circuits, this power-follow current mayor
may not be cleared at a natural currellt zero; in dc circuits the clearing is even more uncertain. Therefore, if the crowbar
device is not designed to provide self-clearing action within specified limits of surge energy and system voltage and
power-follow current, additional means must be provided to open the power circuit.

2.1.1 Filters
The frequency components of a traIlsient are several orders of magnitude above the power frequency of an ac circuit
and, of course, a dc circuit. Therefore, an obvious solution is to install a low-pass filter between the source of transients and
the sensitive load.
The simplest form of filter is a capacitor placed across the line. The impedance of the capacitor forms a voltage divider
with the source impedance, resulting in attenuation of the transient at high frequencies. This simple approach may have
undesirable side effects, such as a) unwanted resonances with inductive components located elsewhere in the circuit
leading to high peak voltages; b) high inrush currents during switching, or, c) excessive reactive load on the power system
voltage. These undesirable effects can be reduced by adding a series resistor - hence, the very popular use ofRC snubbers
and suppression networks. However, the price of the added resistance is less effective clamping.
Beyond the simple RC network, conventional filters comprising inductances and capacitors are widely used for
interference protection. As a bonus, they also offer an effective transient protection, provided that the filter's front-end
components can withstand the high voltage associated with the transient.
There is a fundamental limitation in the use of capacitors and filters for transient protection when the source of
transients in unknown. The capacitor response is indeed nonlinear with frequency, but it is still a linear function of current.
In Chapter 1, it was explained that to design a protection scheme against random transients, it is often necessary to make
an assumption about the characteristics of the impinging transient. If an error in the source impedance or in the
open-circuit voltage is made in that assumption, the consequences for a linear suppressor and a nonlinear suppressor are
dramatically different as demonstrated by the following comparison.

2-2

A SIMPLIFIED COMPARISON BETWEEN PROTECTION WITH LINEAR AND
NONLINEAR SUPPRESSOR DEVICES

Assume an open-circuit voltage of 30()()V (see Figure 2.2):
I. If the source impedance is Zs = 500
with a suppressor impedance of Zv = SO
the expected current is:
3000
I = 50 + S = 51.7A and VR = S x 51.7 = 414V
The maximum voltage appearing across the terminals of a typical nonlinear VI30LA20A varistor at 51.7A is
330V.
Note that:
Zs x I = 50 x 51.7 = 25S6V
Zv x I = S x 51.7 = 414V
= 3000V
2. If the source impedance is only 50 (a 10:1 error in the assumption), the voltage across the same linear SO
suppressor is:
VR = 3000

S

5+S

w-

= IS50V

OO
_Z

>wO:

However, the nonlinear varistor has a much lower impedance; again, by iteration from the characteristic curve,
try 400V at 500A, which is correct for the V130LA20A; to prove the correctness of our "educated guess" we
calculate I.
I = 3000-400V
5

Zs x I =

= 520A

Vc =

5 x 520 = 2600V
400V
= 3000V

which justifies the "educated guess" of 500A in the circuit *
Summary
3000V "OPEN-CIRCUIT" TRANSIENT VOLTAGE

Protective Level
Achieved
Linear SO
Nonlinear Varistor

Assumed Source Impedance
SO
son
414V
IS50V
330V
400V

Similar calculations can be made, with similar conclusions, for an assumed error in open-circuit voltage at a
fixed source impedance. In that case, the linear device is even more sensitive to an error in the assumption. The
calculations are left for the interested reader to work out
• An educated guess, or the result of an iteration - see "Designing with Hanis Varistors," Chapter 4.

The example calculated in the box shows that a source impedance change from an assumed 500 to 50 can
produce a change of about 414V to IS50V for the protective voltage of a typical linear suppressor. With a typical
nonlinear suppressor, the corresponding change is only 330V to 400V. In other words, a variation of only 21 % in the
protective level achieved with a nonlinear suppressor occurs for a 10 to I error in the assumption made on the transient
parameters, in contrast to a 447% variation in the protective level with a linear suppressor for the same error in
assumption. Nonlinear voltage-clamping devices give the lowest clamping voltage, resulting in the best protection against
transients.

2-3

Crn
Zw
cC..J
rno..

co..

2.1.2 Crowbar Devices
This categoryof suppressors, primarily gas tubes (also called "spark gaps") or carbon-block protectors, is widely used in
the communication field where power-follow current is less of a problem than in power circuits. Another form of these
suppressors is the hybrid circuit which uses solid-state or ionic devices where a control circuit causes turn-on of an active
component.
In effect, a crowbar device short-circuits a high voltage to ground. This short will continue until the current is brought to
a low level. A voltage clamping device will never reduce the line voltage below its steady-state value but the crowbar
device often will. Because the voltage (arc or forward-drop) during the discharge is held very low, substantial currents can
be carried by the suppressor without dissipating a considerable amount of energy within the suppressor. This capability is
the major advantage of these suppressors. However, two limitations must be considered.
Volt-Time Response - When the voltage rises across a spark gap, no significant conduction can take place until
transition to the arc mode has occurred by avalanche breakdown of the gas between the electrodes. The delay time,
typically microseconds, leaves the load unprotected during the initial rise.
Since the process is statistical in nature, there is a considerable variation in the sparkover voltage obtained in successive
operations. For some devices, this sparkover voltage also can be substantially higher after a long period of rest than after a
succession of discharges. From the physical nature of the process, it is difficult to produce consistent sparkover voltage for
low voltage ratings. The difficulty is compounded by the effect of manufacturing tolerances on very small gap distances.
One way to alleviate the difficulty is to fill the tube with a gas having a lower breakdown voltage than that of air. However,
this substitution creates a reliability problem if the enclosure seal is lost and the gas is replaced by air. Some applications
require providing a second gap in parallel with the first, with slightly higher sparkover voltage for backup against failure of
the gas tube.
Power-Follow - The second limitation is that a power current from the steady-state voltage source will follow the
surge discharge (called "follow-current" or "power-follow"). In ac circuits, this power-follow current mayor may not be
cleared at a natural current zero; in dc circuits the clearing is even more uncertain. Therefore, if the crowbar device is not
designed to provide self-clearing action within specified limits of surge energy and system voltage and power-follow
current, additional means must be provided to open the power circuit.

2.1.3 Voltage-Clamping Devices
To perform the voltage limiting function, voltage-clamping devices at the beginning of the chapter depend on their
nonlinear impedance in conjunction with the transient source impedance. Three types of devices have been used: reverse
selenium rectifiers, avalanche (zener) diodes and varistors made of different materials, i.e., silicon carbide, zinc oxide, etc.'
Selenium Cells - Selenium transient suppressors apply the technology of selenium rectifiers in conjunction with a
special process allowing reverse breakdown current at high-energy levels without damage to the polycrystalline structure.
These cells are built by developing the rectifier elements on the surface of a metal plate substrate which gives them good
thermal mass and energy dissipation performance. Some of these have self-healing characteristics which allows the device
to survive energy discharges in excess of the rated values for a limited number of operations - characteristics that are
useful, if not "legal" in the unsure world of voltage transients.
The selenium cells, however, do not have the clamping ability ofthe more modern metal-oxide varistors or avalanche
diodes. Consequently, their field of application has been considerably diminished.
Zener Diodes - Silicon rectifier technology has improved the performance of regulator-type zener diodes in the
direction of the design of surge-suppression type avalanche diodes. The major advantage of these diodes is their very
effective clamping, which comes closest to an ideal constant voltage clamp. They are also available in low-voltage ratings.
Since the diode maintains the avalanche voltage across a thin junction area during surge discharge, substantial heat is
generated in a small volume. The major limitation of this type of device is its energy dissipation capability.
Varistors - A varistor functions as a nonlinear variable impedance. The relationship between the current in the
device, I, and the voltage across the terminals, Y, is typically described by a power law: I = kY«.While more accurate and
more complete equations can be derived to reflect the physics of the device,2·3 this definition will suffice here. A more
detailed discussion will be found in Chapter 3.

2-4

The term a (alpha) in the equation represents the degree of nonlinearity of the conduction. A linear resistance has an
a = 1. The higher the value of a, the better the clamp, which explains why a is sometimes used as a figure of merit. Quite
naturally, varistor manufacturers are constantly striving for higher alphas.
Silicon Carbide Varistors - Until the introduction of metal-oxide varistors, the most common type of varistor
was made from specially processed silicon carbide. This material was very successfully applied in high-power,
high-voltage surge arresters. However, the relatively Iowa values ofthis material produce one of two results. Either the
protective level is too high for a device capable of withstanding line voltage or, for a device producing an acceptable
protective level, excessive stand-by current would be drawn at normal voltage if directly connected across the line.
Therefore, a series gap is required to block the normal voltage.
A detailed discussion of series gap/silicon carbide block combinations is beyond the scope ofthis manual, but many
references and standards on the design, testing and application of surge arrestors are available. 4,5
In lower voltage electronic circuits, silicon carbide varistors have not been widely used because of the need for using
a series gap, which increases the total cost and reproduces some of the undesirable characteristics of gaps described
earlier. However, this varistor has been used as a current-limiting resistor to assist some gaps in clearing power-follow
current.
Metal-Oxide Varistors - This family of transient voltage suppressors are made of sintered metal oxides, primarily
zinc oxide with suitable additives. These varistors have a values considerably greater than those of silicon carbide
varistors, typically in the range of an effective value of 15 to 30 measured over several decades of surge current. One
type of varistor, the Harris Varistor, will be described in greater detail in Chapter 3. For the moment, the
description will be limited to what is necessary for understanding the discussion of suppression and
application in this chapter.
The high exponent values (a) of the metal-oxide varistors have opened completely new fields of applications by
providing a sufficiently low protective level and a low standby current. The opportunities for applications extend from
low-power electronics to the largest utility-type surge arresters.

2.2 TRANSIENT SUPPRESSORS COMPARED
Because of diversity of characteristics and nonstandardized manufacturer specifications, transient suppressors are not easy to
compare. A graph (Figure 2.3) shows the relative volt-ampere characteristics ofthe four common devices that are used in I20V
ac circuits. A curve for a simple ohmic resistor is included for comparison. It can be seen that as the alpha factor increases, the
curve's voltage-current slope becomes less steep and approaches an almost constant voltage. High alphas are desirable for
clamping applications that require operation over a wide range of currents.
It also is necessary to know the device energy-absorption and peak-current capabilities when comparisons are made. The
table below includes other important parameters of commonly used suppressors.

':i

-

.....-


Z

100

tt

S~LENIUM ,..?5

Ii..

fO
z

I II I

HLiCON JRS,J JISUR-I

la=ll/

~
I

I

~ESISITOR /V



I

3

4 S

S

10

20

-I

30 4050

SO 100

INSTANTANEOUS CURRENT - AMPS

Figure 2.3 - V-I Characteristics of Four Transient Suppressor Devices

2-5

°en
Zw
c(~

enD..

woO
_Z

>Wa::

OD..

Table 2.1 - Characteristics and Features of Transient Voltage Suppressor Technology

V-I
Characteristics

Device
Type

Leakage

FoUow
onI

Clamping
Voltage

Energy
Capability

Capacitance

Response
Time

Cost

V
Clamping Voltage

--Working
---Voltage --

Ideal
Device

Zero
To
Low

No

Low

High

Low
Or
High

Fast

Low

Zinc Oxide
Varistor

Low

No

Moderate
To
Low

High

Moderate
To
High

Fast

Low

Zener

Low

No

Low

Low

Low

Fast

High

Low

(Latching
Holding I)

Low

Medium

Low

Fast

Moderate

High

Low

Slow

Low
To
High

High

Low

Moderate

High

I

Transient Current

'-k

Voltage

n n m n
: ; ; -

I

'~
- ----- ----MaxI

Limit

~~:~~g
I

A

V

Peak Voltage

Crowbar

(ignition)

-

-

• -----------

~~:~~g

(Zener- SCR

Combination)

Yes

I
V

-

Peak Voltage
~ (ignition)

- -----------

~~:~~g

Spark
Gap

High
Ignition
Voltage
Zero

Yes
Low
Clamp

I

V

-

-I

-

Peak Voltage

(ignition)
Working
----------Voltage

Lower
Ignition
Voltage

Triggered
Spark Gap

Zero

Selenium

Very
High

No

Moderate
To
High

Moderate
To
High

High

Fast

High

Silicon
Carbide
Varistor

High

No

High

High

High

Fast

Relative
Low

Yes

Low
Clamp

I

'-k=:~;;::
I

'-!-~.~::;
I

2-6

Standby power - the power consumed by the suppressor unit at normal line voltage - is an important selection
criterion. Peak standby current is one factor that determines the standby power of a suppressor. The standby power
dissipation depends also on the alpha characteristic of the device.
As an example, a selenium suppressor in Table 2.1 can have a 12mA peak standby current and an alpha of 8 (Figure
2.3). Therefore, it has a standby power dissipation of about O.5W on a 120V rms line (170V peak). A zener-diode
suppressor has standby power dissipation ofless than a milliwatt. And a silicon-carbide varistor, in a 0.75" diameter disc,
has standby power in the 200m W range. High standby power in the lower alpha devices is necessary to achieve a
reasonable clamping voltage at higher currents.
50

ZENER

~::>

20

~

10

eo

~"",",,""mk ~

'"

15
0:

w

I

;0

~ 0.5
>WII:
OD..

6000
5000
4000
3000
2000

>
I

tJ

"'::i
0
>

f;l
::J

""-

"

1000

800
600
500
400
300
200

I

SHORT-TIME SURGE RESPONSE - S

Figure 2.5 - Impulse Breakover of a Gas-Discharge Device Depends Upon the Rate of Voltage
Rise as well as the Absolute Voltage Level

2.3 COMPARISON OF ZENER DIODE AND HARRIS VARISTOR
TRANSIENT SUPPRESSORS
Many circuit designers ask, "Which device is better, a zener or varistor?" Unfortunately, there is no simple answer.
To make this point clear, different features will be covered to aid in realizing the proper choice among the two device
types.

2.3.1 Peak Pulse Power
Transient suppressors have to be optimized to absorb large amounts of power or energy in a short time duration:
nanoseconds, microseconds, or milliseconds in some rare instances.
Electrical energy is transformed into heat and has to be distributed instantaneously throughout the device. Transient
thermal impedance is much more important than steady state thermal impedance, as it keeps peak junction temperature to
a minimum. In other words, heat should be instantly and evenly distributed throughout the device.
The varistor meets these requirements: an extremely reliable device with large overload capability. Zener
diodes on the other hand, transform electrical energy into heat in the depletion region, an extremely small
area, resulting in high peak temperature. From there the heat will flow through the silicon and solder joint to
the copper. Thermal coefficient mismatch and large temperature differentials can result in an unreliable
device for transient suppression.
Figure 2.6 shows Peak Pulse Power vs. Pulse width for the V8ZA2 and the P6KE 6.8, the same devices compared for
leakage current.

2-8

"200

"-

'00

""

"

........ 6wO::

oD.

Figure 2.8 - Characteristic of Zener P6KE 6.8 (on left) Versus
Harris Varistor V8ZA2 (on right)

For a leakage current comparison, 25 zener diode devices were measured at 25°C. Only I device measured 30J1A. The
rest were 150J1A and more. At elevated temperatures, the comparison is even more favorable to the varistor. The zener
diode is specified at lOOOJ1A at 5.sV.
The leakage current of a zener can be reduced by specifying a higher voltage device which would have a lower leakage
current, but the price is a higher clamping voltage and the advantage of the zener disappears.

2.3.5. "Aging"
What is wrong with "Aging?" It can be a pleasant experience considering the alternative - "Instant Death."
Aging is actually a misnomer; it is believed that a varistor's V-I characteristic changes every time energy is absorbed.
That is not the case!
8 x 20l1s wave V31 CP20

4S
44

wa:

L

InPUln

C(I)

Zw
«..J

2.4 PROOF TESTS
To consider protective devices while a system is being designed and to follow with proof tests should be axiomatic, but
historical evidence makes it apparent that this is not so. Thus, retrofit of transient suppressors is common practice.
Actually, one can view this retrofit as part of the trade-off process, with iterative corrections in a calculated risk approach.
It may be justifiable to attempt applying some device with minimal protection in the harsh outside world, and later, when
found necessary, to take corrective action. Hence, retrofit should then be the result of informed choice, not an unforeseen
need for correction. Even here some form of proof testing will be required to ascertain that the retrofit will do the job.9
The nature of the transient environment comes under examination when a retrofit must be applieg. There is some
factual knowledge on the subject, discussed in Chapter 1, but there are also many tentative "generalizations" that require
confirmation. Test standards and specifications, then, become useful guides to the extent that they are not applied or
enforced blindly.s
Some test specifications emphasize voltage tests. This is natural because historically, electrical equipment had dielectric
failures as the major consequence of overvoltages. One can, therefore, specify some voltage test wave that the equipment
must withstand without breakdown. However, with the inclusion of a protective device within the boundaries of an
electronic black box, a simple voltage test is no longer meaningful. What is needed is the two-step approach discussed
below, where the voltage allowed by the protector is determined first, then the effects on the downstream components
determined. Coordination is the key concept.
One point to remember when specifying or performing a test is the difference between a voltage and a current test.
In testing a device for voltage withstand capability, proper recognition must be given to the impedance of the device
being tested and to whether or not it already contains a transient suppressor. It would seem obvious that one does not
specify a voltage test and then crank up the generator until that specified steady-state voltage is achieved at the terminals of
the black box containing a suppressor. Yet this has been attempted!
Conversely, applying a voltage test to a black box containing a suppressor will be meaningless if the source impedance
of the test generator is too high or too low. It is more appropriate, at least in the design stage, to separate the test from the
design steps. First, one specifies the test circuit which will exercise the suppressor: open circuit voltage, (amplitude and
duration) and source impedance. This determines the clamp voltage that will be developed across the shunt-connected
suppressor (Figure 2.11). Second, one designs the protected circuit for this clamp voltage allowing adequate margins.
After the design, this two-step approach can also be applied for demonstrating that withstand capability has been
achieved.

Z SOURCE

SUPPRESSOR

OPEN CIRCUIT VOLTAGE

I~:OCTR~CSTSED
LOAD

~--------------~---------+

Figure 2.11 - Two Steps for Evaluating Protection Requirements

Chapter 7 provides detailed information on varistor testing, both for evaluating varistor characteristics and for
conducting realistic proof tests.

2-12

2.5 UPDATE ON NEW DEVICES:
• Radial Varistors
• High Energy Varistors
• Square Varistors
• Connector Pin Varistors
• Surface Mount Varistors
• RA Series Low Profile Varistors

2.5.1 The "C" III Series

Figure 2.12

The "C" TIl Series (Figure 2.12) is an expanded version of the LA series of metal-oxide varistors, and consists of AC line voltage
rated MOVs with extremely high current and energy handling capabilities. This new "C" III series of MOVs were primarily
designed for the transient voltage surge suppressor (TVSS) environment. They provide the increased level of protection now
deemed to be necessary for the transients expected in this environment.

°Ul

Zw

This new expanded version of the Harris 14mm and 20mm LA series of metal oxide varistors is also available with IOmm lead
spacing, in tape and reel and in a variety of distinctive crimped and trimmed offerings.

UlQ.

2.5.2 The HA Series

>wa:
oil.

ct .....

w-

(J(J

_Z

Figure 2.13

The HA Series (Figure 2.13) is an innovation in varistor packaging technology. This new format gives a very high energy/current
handling capability in a cost effective package.
They are designed to provide secondary surge protection in the outdoor and service entrance environment (distribution panels),
in computers, and also in industrial applications for motor controls and power supplies used in the oil-drilling, mining, and transportation fields.
The HA series of industrial varistors have similar package construction but differ in size, (32 and 4Omm), ratings and characteristics. The design of the HA series of metal oxide varistors provide rigid terminals to insure secure mounting. See Page 9-43 for
specifications.

2.5.3 The NA Series

Figure 2.14

The NA Series (Figure 2.14) are industrial high energy square varistors intended for special applications requiring unique contact
or packaging considerations. The electrode finish of these devices is solderable and can also be used as pressure contacts for stacking applicaltions.
These NA series industrial square varistor is available as a 34mm device, with thicknesses ranging from 1.8mm minimum for the
l30V device to 8.3mm maXimum for the 750V device.

2-13

2.5.4 The Connector Pin Varistor for Transient Voltage Protection in Connectors
The Connector Pin Varistor represents an entirely new approach to transient supression, fonning the active material into a shape
which requires no leads or package. The idea was developed many years ago, but only recently have breakthroughs in the manufacturing process allowed cost effective production of such devices.

ELECTRODE

METALLIZED
ELECTRODE

Figure 2.15 Thbular Varistor (Connector Pin Varistor) CP and CS Series

When assembled into a standard connector, adding no space or weight, they allow effective space saving transient
suppression. Connector Pin Varistors (CPV's) are available in a wide range of voltage ratings with mechanical dimensions
allowing them to be used with 22, 20, or 16 gauge connector pins.
The electrical characteristics are similar to those of traditional varistors and are described in detail on page 9-29 of this
manual.
Although electrically similar, there are some important differences in performance between CPV's and leaded varistors
such as speed of response.
Tests made on lead mounted devices, even with careful attention to minimize lead length, show that the voltage induced
through lead inductance contributes substantially to the voltage appearing across the varistor terminals. These undesirable
induced voltages are proportional to lead inductance and dildt and can be positive or negative.

e

=

di
-d-t- .

L

Vc = Clamping Voltage

Figure 2.16 Shows the Electrical Equivalent of a Lead Mounted Varistor

2-14

r.

v

V8CP22

o

v

ftl2ZAI
~
.0

t""k = 2.5A. 300V

~ I""k = 2.SA. 300V

t'=4nJ~

J

Figure 2.18 Exponential Pulse Applied
to a Pin-Varistor (5V/div., 5Onsldiv.)

Figure 2.17 Exponential Pulse Applied
to a Radial Device (5V/div., SOnsldiv.)

Figure 2.17 shows the positive and negative part of the induced voltage, resulting from a pulse with a rise time of 4ns to
a peak current of 2.5A.
When the above measurement is repeated with a leadless varistor, such as the Connector Pin Varistor, its unique
coaxial mounting allows it to become part of the transmission line. This completely eliminates inductive lead effect.
Pursuing the inductive lead effect further; calculation of the induced voltage as a direct result oflead effect for different
current rise times provides a better understanding of the dil dt value at which the lead effects become significant.
Assuming a current pulse of lOA, 1 inch oflead wire (which translates into approximately 15nH) and rise times ranging
from seconds to femtoseconds, the table below is obtained.

Table I - Induced Voltage in 1 Inch
Leads. Peak Current lOA, at Different
Current Rise Time
L
e
Time
I
1.10°
I • 10-3
I • 1(}"6
I • 10-9
I • 10- 12
I • 10- 18

Isec
Ims
IfJS
Ins
Ips
lfs

lOA
lOA
lOA
lOA
lOA
lOA

15nH
15nH
15nH
15nH
15nH
15nH

vc

150. 10-9
150 • 1(}"6
150.10-3
150
150. 10+3
150. 10+6

e =

2-15

di

dt·

L

Crn

Zw

c(...J

rnD..

w-

uU
_Z
>wa:

cD..

Figure 2.19 illustrates the lead effect even more dramatically for fast rising pulses ranging in rise time from milliseconds
to temtoseconds.

Model

~

15,000,OOOV

"\\, +'-..-'\/'-..-'+.

10,000,000
1,000,000

7.5nH

'\50,OOOV

If

100,000

,

di

'"

» ~

1,000

]

,,

=

e

,,

10,000

~.

L

,,

100
10
10"
Milli

10"
Pico

Micro

Time in Sec

Figure 2.19 Lead Effect of 1 Inch Connection L '" 15nH

A short lead length is important when fast rising pulses (below IOns) must be suppressed. This and other
factors led Harris to the development of new varistor form factors like the Pin Varistor.

Figure 2.20 shows the clamping voltage of a Pin Varistor installed in a connector. The result of a l000V pulse, lOA
amplitude, lOOnsec. duration with 5nsec. rise time results in a clamping voltage of 29V. The 29V includes the overshoot,
dropping at the end of the pulse to 22V, resulting in an average clamping voltage of 25V. For more detailed information
on the Connector Pin Varistor an application note is available.

30V
Nanoseconds
Data

Base
Peak
Area
E.P.W.

-.094
29.086
3.29800E-06
J.I3400E-07

12A

n.,r--..

25

t-

V 20
V
VS 15
S
10

Nanoseconds

10

Dala

1\

Base
Peak
Arca
E.P.W.

6

1"- -I'-'

4

5
0

U

'L

o

-5

.1767
9.65
9. I 2700E-07
9.45800E-08

-2
40

80

120

160

200

0

40

80

120

160

200

Figure 2.20 Clamping Voltage on Connector Equipped with V8CP22 Pin Varistors
(Courtesy of Bendix Connector Operation of Allied, Amphenol Products)

2-16

A
A

VS
S

2.5.2 Surface Mount Varistors

CH

Figure 2.21

Electronics manufacturers are turning to surface-mount technology to lower costs, increase reliability, and reduce the
size and weight of their products. As a consequence, systems designers are looking for surface-mount solutions to the
problem of transient voltage protection.
The increased circuit densities now possible with surface-mount systems have also increased the susceptibility ofthese
tightly-clustered semiconductors to damage or upset by voltage transients. Thus, surface-mount technology demands
a reliable transient voltage protection technology, packaged compatibly with other forms of surface-mount
semiconductors.
Harris has introduced a series of surface-mount varistors for a wide range of applications. These varistors
have significantly lower profiles than traditional radial leaded varistors (Figure 2.22), and are compatible with
most surface-mounting assembly equipment
LA Series
7mm Radial Varistor

SURFACE MOUNT
DEVICE'

Figure 2.22

CH:

• Direct mount chip
• Available in voltage ratings 14VDC to 369V DC
• Chip size is 5rnrn x 8rnrn
• V.L. Approved

2-17

CI/)

«Zw
.....

1/)0..

w-

OO
_Z
>-

we:

co..

Figure 2.23

2.5.3 The RA Series Low Profile Varistor
The RA Series' (Figure 2.23) is an innovation in varistor packaging which has a lower profile than traditional radial varistors. Its precise seating plane increases mechanical stability for secure circuit board mounting _
, a feature that makes the design well suited to high-vibration applications.
Other applications of the RA Series varistor include automotive, motor control, test equipment, computer, consumer electronics, telecommunications, and military markets.
RA Series varistors can be operated at +125°C, the result of advances in materials technology. They are available in voltage and energy ratings up to 275 volts (RMS), 140 joules. Available on tape and reel for auto-insertion, they feature in-line leads for easier automatic placement. See page 9-67 for specifications.

REFERENCES
1. Sakshaug, E.C., J.S. Kresge and S.A. Miske, "A New Concept in Station Arrester Design, "IEEE Trans. PAS-96, No.
2, March-April 1977, pp. 647-656.
2. Philipp, H.R. and L.M. Levinson, ''Low Temperature Electrical Studies in Metal Oxide Varistors - A Clue to
Conduction Mechanisms," Journal of Applied Physics, Vol. 48, April 1977, pp. 1621-1627.
3. Philipp, H.R. and L.M. Levinson, "Zinc Oxide for Transient Suppression," IEEE Trans. PHP, December 1977.
4. Surge Arresters for Alternating Current Power Circuits, ANSI Standard C62.1, IEEE Standard 28.
5. Lightning Arresters. Part I: Nonlinear Resistor Type Arresters for AC Systems, IEC Recommendation 99-1,1970.
6. Matsuoka, M., T. Masuyama and Y. Iida, Supplementary Journal of Japanese Society of Applied Physics, Vol. 39,
1970, pp. 94-101.
7. Harnden, J.D., F.D. Martzloff, W.G. Morris and F.B. Golden, "Metal-Oxide Varistor: A New Way to Suppress
Transients, " Electronics, October 2, 1972.
8. Martzloff, F.D., "The Development of a Guide on Surge Voltages in Low-Voltage AC Power Circuits," Report
81CRD047, General Electric, Schenectady, New York, 1981.
-9. Martzloff, F.D., "Varistor versus Environment: Winning the Rematch," Report 85CRD037, General Electric,
Schenectady, New York, May 1985.

2-18

3
HARRIS VARISTOR BASIC PROPERTIES,
TERMINOLOGY AND THEORY
3.1 WHAT IS A HARRIS VARISTOR?
Varistors are voltage dependent, nonlinear devices which have an electrical behavior similar to back-toback zener diodes. The symmetrical, sharp breakdown characteristics shown in Figure 3.1 enable the varistor
to provide excellent transient suppression performance. When exposed to high voltage transients the varistor
impedance changes many orders of magnitude from a near open circuit to a highly conductive level, thus
clamping the transient voltage to a safe level. The potentially destructive energy of the incoming transient
pulse is absorbed by the varistor, thereby protecting vulnerable circuit components.
The varistor is composed primarily of zinc oxide with small additions of bismuth, cobalt, manganese and other metal
oxides. The structure of the body consists of a matrix of conductive zinc oxide grains separated by grain boundaries
providing P-N junction semiconductor characteristics. These boundaries are responsible for blocking conduction at low
voltages and are the source of the nonlinear electrical conduction at higher voltages.
Since electrical conduction occurs, in effect, between zinc oxide grains distributed thoughout the bulk of the
device, the Harris Varistor is inherently more rugged than its single P-N junction counterparts, such as zener
diodes. In the varistor, energy is absorbed uniformly throughout the body of the device with the resultant
heating spread evenly through its volume. Electrical properties are controlled mainly by the physical
dimensions of the varistor body which is sintered in various form factors such as discs, chips and tubes. The
energy rating is determined by volume, voltage rating by thickness or current flow path length, and current
capability by area measured normal to the direction of current flow.
Harris Varistors are available with ac operating voltages from 4V to 6000V. Higher voltages are limited only by packaging ability. Peak current handling exceeds 70,000A and energy capability extends beyond 1O,000J for the larger units. Package styles include the tiny tubular device for use in connectors and progress in size up to the rugged industrial device line.

-..-n II
U

I!!
:
I

,,

i ll

: II
(-' II

II

II

II
II

II
II
II

II

II

II

II

II

II

II
II

II Ii iI II

II
I1II JI
IIIII

IIIII
II

__•

II

v

!

I

~

50
V

.:. mA

:
I
I

,

,

l -j
iii

--

,,
-

-

Figure 3.1 - Typical Varistor V-I Characteristic

3-1

-~

!flo
~~

wID.. ~
0==

a: a:
D..~

3.2 PHYSICAL PROPERTIES
3.2.1 Introduction
An attractive property of the metal oxide varistor, fabricated from zinc oxide (ZnO), is that the electrical characteristics
are related to the bulk of the device. Each ZnO grain of the ceramic acts as if it has a semiconductor junction at the grain
boundry. A cross-section of the material is shown in Figure 3.2, which illustrates the ceramic microstructure. The ZnO
grain boundaries can be clearly observed. Since the nonlinear electrical behavior occurs at the boundary of each
semiconducting ZnO grain, the varistor can be considered a "multi-junction" device composed of many series and parallel
connections of grain boundaries. Device behavior may be analyzed with respect to the details of the ceramic
microstructure. Mean grain size and grain size distribution playa major role in electrical behavior.

'--- 10011

--0;

Figure 3.2 - Optical Photomicrograph of a Polished and Etched Section of a Varistor

3.2.2 Varistor Microstructure
Varistors are fabricated by forming and sintering zinc oxide-based powders into ceramic parts. These parts
are then electroded with either thick film silver or arc/flame sprayed metal. The bulk of the varistor between
contacts is comprised of ZnO grains of an average size "d" as shown in the schematic model of Figure 3.3.
Resistivity of the ZnO is < 0.3 ohm-cm.
CURRENT

~ELECTRODES

..

- ~~."",-;"",",.--_ ~~~~:~ULAR

....t.
d

Figure 3.3 - Schematic Depiction of the Microstructure of a Metal-Oxide Varistor. Grains of
Conducting ZnO (Average Size d) are Separated by Intergranular Boundaries

3-2

Designing a varistor for a given nominal varistor voltage, VN, is basically a matter of selecting the device thickness such
that the appropriate number of grains, n, are in series between electrodes. In practice, the varistor material is characterized
by a voltage gradient measured across its thickness by a specific volts/mm value. By controlling composition and
manufacturing conditions the gradient remains fixed. Because there are practical limits to the range of thicknesses
achievable, more than one voltage gradient value is desired. By altering the composition of the metal oxide additives it is
possible to change the grain size "d" and achieve the desired result.
A fundamental property ofthe ZnO varistor is that the voltage drop across a single interface 'junction" between grains
is nearly constant. Observations over a range of compositional variations and processing conditions show a fixed voltage
drop of about 2-3V per grain boundary junction. Also, the voltage drop does not vary for grains of different sizes.
It follows, then, that the varistor voltage will be determined by the thickness of the material and the size of the ZnO
grains. The relationship can be stated very simply as follows:
Varistor voltage, VN(dc)
where,
n
and, varistor thickness, D

(3V)n
average number of grain boundaries between electrodes
(n + l)d
VNxd
=---

where,

= average grain size

3

d

The varistor voltage, VN' is defined as the voltage across a varistor at the point on its V-I characteristic where the
transition is complete from the low-level linear region to the highly nonlinear region. For standard measurement purposes,
it is arbitrarily defined as the voltage at a current of ImA.
Some typical values of dimensions for Harris varistors are given in the table below.

Varistor Voltage

Average Grain Size

Volts

Microns

150V RMS
25VRMS

20
80*

n
75
12

Gradient

Device Thickness

V/mmATlmA

mm

150

1.5
1.0

39

·Low voltage formulatIOn.

3.2.3 Theory of Operation
Because of the polycrystalline nature of metal-oxide semiconductor varistors, the physical operation of the device is
more complex than that of conventional semiconductors. Intensive measurement has determined many of the device's
electrical characteristics, and much effort continues to better define the varistor's operation. In this section we will discuss
some theories of operation, but from the user's viewpoint this is not nearly as important as understanding the basic
electrical properties as they relate to device construction.
The key to explaining metal-oxide varistor operation lies in understanding the electronic phenomena occurring near the
grain boundaries, or junctions between the zinc oxide grains. While some of the early theory supposed that electronic
tunneling occurred through an insulating second phase layer at the grain boundaries, varistor operation is probably better
described by a series-parallel arrangement of semiconducting diodes. In this model, the grain boundaries contain defect
states which trap free electrons from the n-type semiconducting zinc oxide grains, thus forming a space charge depletion
layer in the ZnO grains in the region adjacent to the grain boundaries. 6
Evidence for depletion layers in the varistor is shown in Figure 3.4 where the inverse of the capacitance per boundary
squared is plotted against the applied voltage per boundary.7 This is the same type of behavior observed for
semiconductor abrupt P-N junction diodes. The relationship is:
2(Vb + V)

qEsN

Where Vb is the barrier voltage, V the applied voltage, q the electron charge, ES the semiconductor permittivity and N is
the carrier concentration. From this relationship the ZnO carrier concentration, N, was determined to be about 2xlO I7 per
cm3•7 In addition, the width of the depletion layer was calculated to be about 1000 Angstrom units. Single junction studies
also support the diode mode1.9
It is these depletion layers that block the free flow of carriers and are responsible for the low voltage insulating behavior
in the leakage region as depicted in Figure 3.5. The leakage current is due to the free flow of carriers across the field lowered
barrier, and is thermally activated, at least above about 25°C.
Figure 3.5 shows an energy band diagram for a ZnO-grain boundary-ZnO junction. II The left-hand grain is forward
biased, VL, and the right side is reverse biased to VR • The depletion layer widths are XL and X R , and the respective barrier
heights are ifJ L and ifJ R • The zero biased barrier height is ifJ o ' As the voltage bias is increased, ifJ L is decreased and ifJ R is
increased, leading to a lowering of the barrier and an increase in conduction.
The barrier height ifJ L of a low voltage varistor was measured as a function of applied voltage ll and is presented in
Figure 3.6. The rapid decrease in the barrier at high voltage represents the onset of nonlinear conduction. 12

Ei - - - - - - " "

8·0

8

12

VA PER BOUNDARY

Figure 3.4 - Capacitance-Voltage Behavior of
Varistor Resembles a Semiconductor
Abrupt-Junction Reversed Biased Diode.
Nd - 2 x l017/cm3

$

Ii

Figure 3.5 - Energy Band Diagram of
a ZnO-Grain Boundary-ZnO Junction

0.8

--.J-~

~ 0.6

~~
o
\oJ

i

0.4

0.2

12
VOLTAGE II

Figure 3.6 - Thermal Barrier as a Function of Applied Voltage

3-4

Transport mechanisms in the nonlinear region are very complicated and are still the subject of active research. Most
theories draw their inspiration from semiconductor transport theory and the reader is referred to the literature for more
information.3.5.13.14.15
Turning now to the high current upturn region in Figure 3.1 0 (see page 3-8), we see that the V-I behavior approaches an
ohmic characteristic. The limiting resistance value depends upon the electrical conductivity of the body of the
semiconducting ZnO grains, which have carrier concentrations in the range of 1017 to 1018 per cm3. This would put the
ZnO resistivity below 0.30cm.

3.3 VARISTOR CONSTRUCTION
The process offabricating a Harris Varistoris illustrated in the flow chart of Figure 3.7. The starting material
may differ in the composition of the additive oxides, in order to cover the voltage range of product.
ZnO

j~."" '"' ' ' '""

j

eo" """" roo

FINAL PRODUCT
TO ELECTRICAL
TEST

Figure 3.7 - Schematic Flow Diagram of Harris Varistor Fabrication

Device characteristics are determined at the pressing operation. The powder is pressed into a form of predetermined
thickness in order to obtain a desired value of nominal voltage. To obtain the desired ratings of peak current and energy
capability, the electrode area and mass of the device are varied. The range of diameters obtainable in disc product offerings
is listed here:
Nominal Disc Diameter - mm
Of course, other shapes, such as rectangles, are also possible by simply changing the press dies. Other ceramic
fabrication techniques can be used to make different shapes. For example, rods or tubes are made by extruding and cutting
to length. After forming, the green (i.e. unfired) parts are placed in a kiln and sintered at peak temperatures in excess of
1200 0 C. The bismuth oxide is molten above 825 0 C, assisting in the initial densification of the polycrystailine ceramic. At
higher temperatures, grain growth occurs, forming a structure with controlled grain size.
Electroding is accomplished, for radial and chip devices, by means of thick film silver fired onto the ceramic surface.
Wire leads or strap terminals are then soldered in place. A conductive epoxy is used for connecting leads to the axial3mm
discs. For the larger industrial devices (40 and 60mm diameter discs) the contact material is arc sprayed aluminum, with
an overspray of copper if necessary to give a solderable surface.
Many encapsulation techniques are used in \he assembly of the various Harris Varistor packages. Most radials and some
industrial devices (HA Series) are epoxy coated in a fluidised bed, whereas epoxy is "spun" onto the axial device. Radials
are also available with phenolic coatings applied using a wet process. The PA series package consists of plastic molded
around a 20mm disc sub-assembly. The RA, DA, and DB series devices are all similar in that they all are composed of discs
or chips, with tabs or leads, encased in a molded plastic shell filled with epoxy. Different package styles allow variation in
energy ratings, as well as in mechanical mounting. Figures 3.8 & 3.9 illustrate several package forms.

3-5

HARRIS
SEMICONDUCTOR

3-6

~,

Dwgs. Not to Scale

I

I

I

Figure 3.9A
Cross-Section of MA Package

I

I

I

I

I

I

:

I

I

I
I

I

I

I

I

I

,

I
I

I
I
I

,

,

(
PA Series

Figure 3.9B
Cross-Section of
Radial Lead Package

Figure 3.9C
Pictorial View of
Power MOV Package

DB Series

DAIDD Series

Figure 3.9D - Pictorial View of High Energy Packages DA, DB and BAIBB Series

3-7

F~

3.9showsCOllstruction details of some packages. Dimensions of the ceramic, by package type, are given below:
Package Type

Ceramic Dimensions

Direct Surface Mount

- CH, AUML, ML Series

5 x 8mm Chip, 1206,1210,1812,2220

Connector Pin

-CP, CS Series

22, 20, 16 Gauge Tube

Axial Leaded

-MA Series

3mm Diameter Disc

Radial Leaded

-ZA, LA, "C'1II Series

5,7,10,14, 20mm Diameter Discs

Radial Leaded Low Profile

-RA Series

5 x 8mm, 10 x 16mm, 14 x 22 Chips

Power

-PA Series

20mm Diameter Disc

Industrial Packages

-HA Series
-DA, DB Series
-BA, BB Series

32, 40mm Diameter Disc
40mm Diameter Disc
60mm Diameter Disc

Industrial Discs

-CA, NA Series

32, 40, 60mm Diameter Discs
34mmSquare

Arrester

-AS Series

32, 42, 52, 60mm Diameter Discs

3.4 ELECTRICAL CHARACTERIZATION
3.4.1 Varistor V-I Characteristics
Varistor electrical characteristics are conveniently displayed using log-log format in order to show the wide range of the
V-I curve. The log format also is clearer than a linear representation which tends to exaggerate the nonlinearity in
proportion to the current scale chosen. A typical V-I characteristic curve is shown in Figure 3.10. This plot shows a wider
range of current than is normally provided on varistor data sheets in order to illustrate three distinct regions of electrical
operation.

t__

_LEAKAGE-------....
REGION

-NORMAL VARISTOR

OPERATION------+l~1

UPTURN_
REGION

1000

i

SOD

~jI

I
200

I
I
-'1t-~

100

50

20

jl
0/---

i

C-'~I/
0:/

..--

7

H--

'~'kva

>:

0

.:.~r f - -

"I

0:/

/

f

(TYPICAL Vl30LA20AJ

II

----L.
10- 6

10- 5

10- 4

I

10- 3
10 2
10.1
100
CURRENT - AMPERES

I

10

Figure 3.10 - Typical Varistor V-I Curve Plotted on Log-Log Scale

3-8

3.4.2 Equivalent Circuit Model
An electrical model for the varistor can be represented by the simplified equivalent circuit of Figure 3.11.

(TYPICAL V 130LA20A)

C
(0.002I'F)

-L

T

ROFF

(lOOOMlJ.i

'----+-----'

Figure 3.11 - Varistor Equivalent Circuit Model

3.4.3 Leakage Region of Operation
At low current levels, the V-I Curve approaches a linear (ohmic) relationship and shows a significant temperature
dependence. The varistor is in a high resistance mode (approaching 109 ohms) and appears as an open circuit. The
nonlinear resistance component, R x, can be ignored because ROFF in parallel will predominate. Also, RON will be
insignificant compared to R OFF'

Figure 3.12 - Equivalent Circuit at Low Currents
For a given varistor device, capacitance remains approximately constant over a wide range of voltage and frequency in
the leakage region. The value of capacitance drops only slightly as voltage is applied to the varistor. As the voltage
approaches the nominal varistor voltage, the capacitance abruptly decreases. Capacitance remains nearly constant with
frequency change up to 100kHz. Similarly, the change with temperature is small, the 25°C value of capacitance being
well within ± 10% from -40°C to +125°C.
The temperature effect of the V-I characteristic curve in the leakage region is shown in Figure 3.13. A distinct
temperature dependence is noted.
100
J"

80

L'

~

~

./

. /1/'//

/ /V/

,/

L

/ / j II

// III

v

/

--

10

-9

J

II V/

/ V/

/ I

l/~tVI5/i/
10- 7

125°C

10-6

SPECIM jN(30LAtA

10- 5

10- 4

VARISTOR CURRENT (AMPERES, DC)

Figure 3.13 - Temperature Dependence of the Characteristic Curve in the Leakage R

3-9

I L -_ __

The relation between the leakage current, I, and temperature, T, is:
-VB/kT
1= 10 E
where: 10 = constant
k = Boltzmann's Constant
VB= 0.9 eV
The temperature variation, in effect, corresponds to a change in R oFF' However, RoFF remains at a high resistance value
even at elevated temperatures. For example, it is still in the range of 10 to 100 megaohms at 125°C.
Although
frequency.

ROFF

is a high resistance it varies with frequency. The relationship is approximately linear with inverse
1

RoFF~­

f

However, the parallel combination of ROFF and C is predominantly capacitive at any frequency of interest. This is because
the capacitive reactance also varies approximately linearly with lIf.
At higher currents, at and above the milliamp range, temperature variation becomes minimal. The plot of the
temperature coefficient (dvI dt) is given in Figure 3.14. It should be noted that the temperature coefficient is negative and
. decreases as current rises. In the clamping voltage range of the varistor (I > lA), the temperature dependency approaches
zero.

p

~
!2:w
u

....II-----LEAKAGE REGION
.1 I SAMPLE TYPE
o Vl30LA10A

u::
u..

-,1

o

-,2

a:

w

-,3

!;;:

-.4

w
Q.
:2
w

-,5

w

V/1'

//

::J

V22ZA3

/

(,)

a:

NORMAL
I OPERATION-

Typical Temperature
Coefficient of Voltage
Versus Curren~ 14mm Size,
-55 to +125°C

/
10.5 10.4

10.3

10"

10"

10°

10'

10'

103

CURRENT (AMPERES)

~

Figure 3.14- Relation of Temperature Coefficient dv/dt to Varistor Current

3.4.4 Normal Varistor Region of Operation
The varistor characteristic follows the equation I = kVa, where k is a constant and the exponent a defines the degree of
nonlinearity. Alpha is a figure of merit and can be determined from the slope of the V-I curve or calcuated from the
formula:

a

In this region the varistor is conducting and Rx will predominate over C, RON and ROFF" Rx becomes many orders of
magnitude less than ROFF but remains larger than RON'

Figure 3.15 - Equivalent Circuit at Varistor Conduction

3-10

During conduction the varistor voltage remains relatively constant for a change in current of several orders of
magnitude. In effect, the device resistance, Rx, is changing in response to current. This can be observed by examining the
static or dynamic resistance as a function of current. The static resistance is defined by;

Rx =

V

and the dynamic resistance by:
Zx =

dv
di

= Vial = Rxla

Plots of typical resistance values vs. current, I, are given in Figure 3.16.
500

~

':i
o
>

100

r--...

50

I-

::>
Uz

"'a. to
z-

~~
~'"

5

~~

"'I-

I

~~

.5

u«

'"

""

i'..

"'a.
o

I

-0.05

0.0 I
0.01

I~

'" '"
~

,""",

'""r

"-

0.1

I

'"'"'""10

'" ~

"-

I

~ I'-.
"'-

0.00 I
0.01

100

PEAK CURRENT - AMPERES

0.1

1.0

10

100

PEAK CURRENT - AMPERES

Figure 3.16A - Rx Static Varistor Resistance

Figure 3.16B - Zx Dynamic Varistor Resistance

3.4.5 Upturn Region of Operation
At high currents, approaching the maximum rating, the varistor approximates a short-circuit. The curve departs from
the nonlinear relation and approaches the value of the material bulk resistance, about 1-10 ohms. The upturn takes place
as Rx approaches the value of RON' Resistor RON represents the bulk resistance of the zinc oxide grains. This resistance is
linear (which appears as a steeper slope on the log plot) and occurs at currents 50 to 50,000A, depending on the varistor
size.

Figure 3.17 - Equivalent Circuit at Varistor Upturn

3.4.6 Speed of Response and Rate Effects
The varistor action depends on a conduction mechanism similar to that of other semiconductor devices. For this reason,
conduction occurs very rapidly, with no apparent time lag - even into the nanosecond range. Figure 3.18 shows a
composite photograph of two voltage traces with and without a varistor inserted in a very low inductance inpulse
generator.The second trace (which is not synchronized with the first, but merely superimposed on the oscilloscope screen)
shows that the voltage clamping effect of the varistor occurs in less than one nanosecond.
In the conventional lead-mounted devices, the inductance of the leads would completely mask the fast action of the varistor; therefore, the test circuit for Figure 3.18 required insertion of a small piece of varistor material in a coaxial line to demonstrate the intrinsic varistor response.

3-11

Tests made on lead-mounted devices, even with careful attention to minimizing lead length, show that the voltages
induced in the loop formed by the leads contribute a substantial part of the voltage appearing across the terminals oCa
varistor at high current and fast current rise. Fortunately, the currents which can be delivered by a transient source are
invariably slower in rise time than the observed voltage transients. The applications most frequently encountered for
varistors involve current rise times longer than O.5jls.

TRACE I
LOAD VOLTAGE
WITHOUT VARISTOR

TRACE 2
LOAD VOLTAGE
CLAMPED
BY VARISTOR

500 PICOSECONDS/DIV.

Figure 3.18 - Response of a ZnO Varistor to a Fast Rise Time (500 Picosecond) Pulse
Voltage rate-of-rise is not the best term to use when discussing the response of a varistor to a fast impulse (unlike spark
gaps where a finite time is involved in switching from non-conducting to conducting state). The response time of the
varistor to the transient current that a circuit can deliver is the appropriate characteristic to consider.
1000
800

~JJJJJJ

1111
WAVESHAPE-

(LEAD AREA

10-6

VOLTAGE (VOLTS)

'Nldc)

100

CURRENT (AMPERES)

Figure 3.20 - I-V Graph Illustrating Symbols and Defmitions

3.5.2 Varistor Characteristics (IEEE Standard C62.33-1982 Subsection 2.3 and 2.4)
Terms and Descriptions

SymbQI

2.3.1 Clamping Voltage. Peak voltage across the varistor measured under conditions of a specified peak
pulse current and specified waveform. Note: Peak voltage and peak currents are not necessarily coincidental
in time.
2.3.2 Rated Peak Single Pulse Transient Currents (Varistor). Maximum peak current which may be
applied for a single 8120J.ls impulse, with rated line voltage also applied, without causing device failure.
2.3.3 Lifetime Rated Pulse Currents (Varistor). Derated values of Itm for impulse durations exceeding
that of an 8120J.ls waveshape, and for multiple pulses which may be applied over device rated lifetime.
2.3.4 Rated RMS Voltage (Varistor). Maximum continuous sinusoidal rms voltage which may be
applied.
2.3.5 Rated DC Voltage (Varistor). Maximum continuous dc voltage which may be applied.
2.3.6 DC Standby Current (Varistor). Varistor current measured at rated voltage, Vm(dC)'

Vc

I,m
-

Vm(ac)
Vm(dc)

ID

2.4 For certain applications, some of the following terms may be useful.
2.4.1 Nominal Varistor Voltage. Voltage across the varistor measured at a specified pulsed dc current,
IN(dc)' of specific duration. IN(dc) of specific duration. IN(dc) is specified by the varistor manufacturer.
2.4.2 Peak Nominal Varistor Voltage. Voltage across the varistor measured at a specified peak ac current,
IN(ac)' of specific duration. IN(ac) is specified by the varistor manufacturer.
2.4.3 Rated Recurrent Peak Voltage (Varistor). Maximum recurrent peak voltage which may be applied
for a specified duty cycle and waveform.

3-13

VN(dc)
VN(ac)
Vpm

Terms and Descriptions (cont'd)

Symbol

2.4.4 Rated Single Pulse Transient Energy (Varistor). Energy which may be dissipated for a single
impulse of maximum rated current at a specified waveshape, with rated rms voltage or rated dc voltage also
applied, without causing device failure.
2.4.5 Rated Transient Average Power Dissipation (Varistor). Maximum average power which may be
dissipated due to a group of pulses occurring within a specified isolated time period, without causing device
failure.
2.4.6 Varistor Voltage. Voltage across the varistor measured at a given current, Ix'
2.4.7 Voltage Clamping Ratio (Varistor)~ A figure of merit measure of the varistor clamping effectiveness
as defined by the symbols V/Vm(ac)' Y.,/Vm(dc)'
2.4.8 Nonlinear Exponent. A measure of varistor nonlinearity between two given operating currents, I}
and 12, as described by I = kV« where k is a device constant, I} ::; I ::; 12, and
_ log I/I}

Wtm

a}2

P'(AV)m

-

log V/V2
2.4.9 Dynamic Impedance (Varistor). A measure of small signal impedance at a given operating point as
defined by:

Zx

zx =~
dI
x

2.4.10 Resistance (Varistor). Static resistance of the varistor at a given operating point as defined by:

=~

R
x

Ix

2.4.11 Capacitance (Varistor). Capacitance between the two terminals of the varistor measured at
specified frequency and bias.
2.4.12 AC Standby Power (Varistor). Varistor ac power dissipation measured at rated rms voltage Vm(ae)'

C

2.4.13 Voltage Overshoot (Varistor). The excess voltage above the clamping voltage of the device for a
given current that occurs when current waves oflessthan 811S virtual front duration are applied. This value
may be expressed as a % of the clamping voltage (Ve) for an 8120 current wave.
2.4.14 Response Time (Varistor). The time between the point at which the wave exceeds the clamping
voltage level (Ve) and the peak of the voltage overshoot. For the purpose of this definition, clamping voltage
as defined with an 8120l1s current waveform of the same peak current amplitude as the waveform used for
this response time.
2.4.15 Overshoot Duration (Varistor). The time between the point at which the wave exceeds the
clamping voltage level (Vc> and the point at which the voltage overshoot has decayed to 50% of its peak. For
the purpose of this definition, clamping voltage is defined with an 8120l1s current waveform of the same
peak current amplitude as the waveform used for this overshoot duration.

3.5.3 Test Waveform
At high current and energy levels, varistor characteristics are measured, of necessity, with an impulse waveform. Shown
in Figure 3.21 is the ANSI Standard C62.l waveshape, an exponentially decaying waveform representative oflightning
surges and the discharge of stored energy in reactive circuits.
The 8120l1s current wave (811s rise and 20l1s to 50% decay of peak value) is used as a standard, based on industry
practices, for the characteristics and ratings described. One exception is the energy rating (Wtm), where a longer waveform
of 1011 OOOI1S is used. This condition is more representative ofthe high energy surges usually experienced from inductive
discharge of motors and transformers. Varistors are rated for a maximum pulse energy surge that results in a
varistor voltage (VN ) shift ofless than ±10% from initial value.

3-14

100
,,90

----------It
--------

I
I
I
I
I
I
I
I
I
I

I

"-

o

f-

z

50

----~-------------

I

w

I

u

a:

I

w

I



I

I
I

IMPULSE DURATION

~VIRTUAL

.1

FRONT DURATION
= 1.25 X RISETIME FROM 10% TO 90%

Figure 3.21 -

Definition of Pulse Current Waveform

-~
fflo
I=w
[[:I:

wIa.
,

O:E

[[[[

REFERENCES

a.j!:!

1. Harnden, J.D., F.D. Martzloff, W.G. Morris and F.B. Golden, "The GE-MOV® Varistor - The Super Alpha
Varistor," Electronics, Vol. 45, No. 21, 1972, p. 91.
2. Morris, W.G., "Electrical Properties of ZnO-Bi203 Ceramics," Journal of the Am. Ceram. Soc., Vol 56, 1973.
3. Matsuoka, M., "Non-Ohmic Properties of Zinc Oxide Ceramics," Japanese Jnl. Appl. Phys., Vol. 10,1971, p. 736.
4. Mahan, G., L. Levinson and H. Philipp, "Single Grain Junction Studies at ZnO Varistors - Theory & Experiment, "
Report #78CRFI60, General Electric, Schenectady, N.Y., 1978. Forthcoming in Applied Physics Letters.
5. Mahan, G., L. Levinson and H. Philipp, "Theory of Conduction in ZnO Varistors," Journal of Applied Physics (in
press).
6. Levine, J.D., 'Theory of Varistor Electronic Properties," Critical Review of Solid State Science,S, 1975, pp.
597-608.
7. May, J .E., "Carrier Concentration and Depletion Layer Model of Zinc Oxide Varistors," Bulletin of the American
Ceramic Society, Vol. 57, No.3, 1978, p. 335.
8. Sze, S.M., "Physics of Semiconductor Devices," John Wiley & Sons, New York, N.Y., 1969.
9. Einzinger, R., "Microcontact Measurement of ZnO Varistors," Ber. Dt. Keram, Vol. 52, 1975, pp. 244-245.
10. Lou, L.F., "Current-Voltage Characteristics of ZnO-Bi203 Heterojunction, " Journal of Applied Physics, Vol. 50,
1979, p. 555.
11. Lou, L.F. "Semiconducting Properties of ZnO-Grain Boundary-ZnO Junctions in Ceramic Varistors," Appl. Phys.
Letters, Vol. 36, 1980, pp. 570-572.
12. Lou, L.F., and J.E. May, Unpublished Research, General Electric, Syracuse, N.Y., 1981.
13. Morris, W., "Physical Properties ofthe Electrical Barriers in Varistors, " J. Vac. Sci. Technol., 13, 1976, pp. 926-931.
14. Bernasconi, J., S. Strassler, B. Knecht, H. Klein and A. Menth, Solid State Communication, Vol. 21, 1977, pp.
867-869.
15. Pike, G. and C. Seager, "The DC Voltage Dependence of Semiconductor Grain-Boundary Resistance," Journal of
Appl. Phys., Vol. 50,1979, pp. 3414-3422.

3-15

4
DESIGNING WITH HARRIS VARISTORS
4.1 SELECTING THE VARISTOR
The varistor must operate under steady-state and transient conditions. Device ratings allow a selection of the proper size
device to insure reliable operation. The selection process requires a knowledge of the electrical environment. When the
environment is not fully defined, some approximations can be made.
For most applications, selection is a five-step process:
I) Determine the necessary steady-state voltage rating (working voltage)
2) Establish the transient energy absorbed by the varistor
3) Calculate the peak transient current through the varistor
4) Determine power dissipation requirements
5) Select a model to provide the required voltage-clamping characteristic
Refer also to page 9-6 "How to select a Harris Varistor," and page 9-8 "How to
connect a Harris Varistor."

4.1.1 Steady-State Voltage Rating
Consider the maximum steady-state voltage applied to the varistor including any high line conditions (i.e., 110% or
more of nominal voltage). Ratings are given for sinusoidal ac and constant dc. If a nonsinusoidal waveform is applied, the
recurrent peak voltage should be limited tov'2x Vm(ac)"
Specifications for the LA Series varistor are shown in Figure 4.1 for l30V ac rated devices to illustrate the use ofthe
ratings and characteristics table.
Characteristics (2S°C)

Maximum Ratings (8S°C)

Continuous
Model
Number

VI30LAI
VI30LA2
VI30LAS
V130LAIOA
VI30LA20A
V130LA20B

Model Device
Size Marking
Dia.
(mm)

7
7
10
14
20
20

1301
1302
1305
130LlO
130L20
130L20B

RMS
Voltage

DC
Voltage

Vm(IlC)

Volts

V""ok'
Volts

130
130
130
130
130
130

175
175
175
175
175
175

Maximum

Transient
Varistor
Voltage
@lmADC
Test
Current

Oamping
Voltage
Vc@Test
Current

Typical
Capacilance

Energy

Peak
Current

(10/1000/1s)

(8/20/1s)

W..

I,m

Min.

VN(de)

Max.

Vc

I.

f - 0.1·1 MHz

Joules

Amperes

Volts

Volts

Volts

Volts

Amps

Picofarads

11
11
20
38
70
70

1200
1200
2500
4500
6500
6500

184
184
184
184
184
184

200
200
200
200
200
200

255
228
228
228
228
220

390
340
340
340
340
325

10
10
25
50
100
100

180
180
450
1000
1900
1900

(8/20/1s)

Figure 4.1 - Ratings and Characteristics Table

4-1

Indicates an ac voltage rating of 130V ac RMS for LA Series.

Model Number

These models can be operated continuously with up to130V ac RMS at 50-60 Hz
applied. They would be suitable for 117V ac nominal line operation and would allow
for a 110% high line condition.

Vm(ac)

Operation is allowable with up to 175V dc constant voltage applied continuously.

Vm(dc)
VN(dc)

Min.

Indicates the minimum varistor terminal voltage that will be measured with lmA dc
applied. This is a characteristic of the device and is a useful parameter for design or for
incoming inspection.

VN(dC)

Max. @ ImA de

Indicates the maximum limit of varistor terminal voltage measured at ImA dc.

The format for the model number designation is shown below. Note, the model series are grouped in two forms. One
group is based on the ac voltage rating for applications primarily across the power line. The second group is based on the
VN(dc) characteristic voltage.
@

V

130

LA

20A

--,--LZ~~
MAXIMUM
RMS OR DC
APPLIED
VOLTAGE

HARRIS
VARISTOR

CA,NA,HA,BA,BB,DA,DB,PA

PRODUCT
SERIES

RELATIVE
SELECTION ENERGY
CLAMPING
INDICATOR VOLTAGE (A OR B)

HIGH ENERGY AND POWER PACKAGES
RADIAL LEAD (LINE VOLTAGE & ABOVE)
TUBULAR PACKAGES

LA
"C" TIl, CS, CP

V220MA4B

L/1~

~HARIu-oC-SVARISTOR

MA
ZA
ML,AUML,CH
RA

VN(d<)
NOMINAL
VARISTOR
VOLTAGE

PRODUCT
SERIES

RELATIVE
SELECTION ENERGY
CLAMPING
INDICATOR VOLTAGE(A'ORB)

AXIAL LEAD
RADIAL LEAD (LOW VOLTAGE)
DIRECT MOUNT CHIPS
LOW PROFILE RADIAL LEAD

Figure 4.2 - Model Number Nomenclature

4-2

4.1.2 Energy
Transient energy ratings are given in the W tm column of the specifications in joules (watt-second). The rating is the
maximum allowable energy for a single impulse of 10/1000ps current waveform with continuous voltage applied.
Energy ratings are based on a shift of VN of less than ± 10% of initial value.
When the transient is generated from the discharge of an inductance (i.e., motor, transformer) or a capacitor, the source
energy can be calculated readily but, in most cases the transient is from a source external to the equipment and is of
unknown magnitude. For this situation an approximation technique can be used to estimate the energy of the transient
absorbed by the varistor. The method requires finding the transient current and voltage through the varistor. To determine
the energy absorbed the following equation applies:
E

=foT

Vc (t)I(t).6.t

=KVcIT

where I is the peak current applied, Vc is the clamp voltage which results, T is the impulse duration and K is a constant. K
values are given in Figure 4.3 for a variety of waveshapes frequently encountered. The K value and pulse width
correspond to the current waveform only, assuming the varistor voltage waveform is almost constant during the current
impulse. For complex waveforms, this approach also can be used by dividing the shape into segments that can be treated
separately.
WAVESHAPE

EQUATION

K*

~

IpK sin (~t)

0.637

I-T -I

T

1

~
.51 pK

~
~
1-·5IPK

1

EQUATION

K*

IpK e-tf1 .44 ,

1.4

T.J

t
IpK(T)

k;J:K
r---l
1

r

WAVESHAPE

0.5

r

---I

::t:

I-

IpK

§E~

1.0

1

ClO

zl-

-en
z-

Cla:

Cii~

w
C

1

'lpK sin (711) e-'"

0.86

*Based upon alpha of 25 10 40.

Figure 4.3 - Energy Form Factor Constants
Consider the condition where the exponential waveform shown below is applied to a V130LAI Harris Varistor.

5,LLs

50,LLs

.1

The waveform is divided into two parts that are treated separately using the factors of Figure 4.3: current waveform
section (I) 0 to 5ps to infinity. The maximum voltage across the VI30LAI at 100A is found to be 500V from the V-I
characteristics of the specification sheet.
Section(l)

E = KVc IT = (0.5) (500) (100) (5) (10-6)

= O.13J

Section (2)

E = KVc IT = (1.4) (500) (100) (50-5) (10--6)

= 3.15J
3.28J Total

The specifications of Figure 4.1 indicate a rating of III for this device which is adequate for the application.

4-3

4.1.3 Peak Current
The peak current rating can be checked against the transient current measured in the circuit. If the transient is generated
by an inductor, the peak current will not be more than the inductor current at the time of switching. Another method for
finding the transient current is to use a graphical analysis. When the transient voltage and source impedance is known, a
Thevenin equivalent circuit can be modeled. Then, a load line can be drawn on the log -log, V-I characteristic as shown
in Figure 4.4. The two curves intersect at the peak current value.

w

'"~ Voc
.

VR = Voc - IZs

o
>
0:

~

ii'
~

Vc

~h..AM~Y9!:J~G.£

__ _
VARISTOR V-I
CHARACTERISTIC

'"'3
Iv

Voc 1Zs

LOG VARISTOR CURRENT - AMPERES

1) Equivalent Circuit

2) Graphicsl Analysis to Determine Peak 1

Figure 4.4 - Determining Varistor Peak Current from a Voltage Source Transient

The rated single pulse current, I,m' is the maximum allowable for a single pulse of 8120ps exponential waveform
(illustrated in Figure 3.21). For longer duration pulses, I,m should be derated to the curves in the varistor specifications.
Figure 4.5 shows the derating curves for 7mm size, LA series devices. This curve also provides a guide for derating current
as required with repetitive pulsing. The designer must consider the total number of transient pulses expected during the life
of the equipment and select the appropriate curve.

,

2000
1000
500

200

MODEL SIZE 7mm
V130LA1 - V300LA4

2

~

:"-.

10
100

10

0

'0'
",'0,

......

0"-10
o

INO

5~fI

~

t:::::;::.- :---..

- q 0;:,,;

2

,

20

II

~ ~!!!
100

1000
IMPULSE DURATION -)is

Figure 4.5 - Pulse Ratings

4-4

10,000

Where the current waveshape is different from the exponential waveform of Figure 3.18, the curves of Figure 4.5 can
be used by converting the pulse duration on the basis of equivalent energy. This is easily done using the constants given in
Figure 4.3. For example, suppose the actual current measured has a triangular waveform with a peak current of lOA, a
peak voltage of 340V and an impulse duration of 500IlS.
Then:

E

= (.5)(10)(340)(500)(10-6 )
= 850mJ

The equivalent exponential waveform of equal energy is then found from:

= EEXP
850mJ = 1.4 Vc I r EXP

ETRIANGULAR

The exponential waveform is taken to have equal Vc and I values. Then,
850mJ
1.4 (340) (10)
= 1791ls

K* r*

Or:

1.4

Where: K* and r* are the values for the triangular waveform and r EXp is the impulse duration for the equivalent
exponential waveform.
The pulse rise portion of the waveform can be ignored when the impulse duration is five times or more longer. The
pulse life for the above example would exceed 1()4 pulses from the pulse life curves shown in Figure 4.5.

4.1.4 Power Dissipation Requirements
Transients generate heat in a suppressor too quickly to be transferred during the pulse interval. Power dissipation
capability is not necessary for a suppressor, unless transients will be occurring in rapid succession. Under this condition,
the power dissipation required is simply the energy (watt-seconds) per pulse times the number of pulses per second. The
power so developed must be within the specifications shown on the ratings tables. It is to be noted that varistors can only
dissipate a relatively small amount of average power and are, therefore, not suitable for repetitive applications that involve
substantial amounts of average power dissipation. Furthermore, the operating values need to be derated at high
temperatures as shown in Figure 4.6.

3:!fi

100
90
c 80
~ 70
a: 60
u. 50
o 40
30
~ 20
a:
w 10

rv

Q.

o U\,

-55

AUML, CIf, CP,
. ML, RA SERIES

~

~~

'\.

" '\.

--

I"""'\.

BAlBB, CA, DAlDB, LA, "C" III
HA, NA, MA, PA, ZA SERIES

!Z

,

cs\

'\.

\

,

\

,
~

'\.

\
\

'\.
50

60

70

80

\

90 100 110 120 130 140 150

AMBIENT TEMPERATURE -

CC

Figure 4.6 - Current, Energy, Power Rating vs. Temperature

4-5

4.1.5 Voltage Clamping Selection
Transient V-I characteristics are provided in the specifications for all models of these varistors. Shown
below in Figure 4.7 are curves for 130V ac rated models of the LA series. These curves indicate the peak
terminal voltage measured with an applied 8/20ps impulse current. For example, if the peak impulse current
applied to a V130LA2 is lOA, that model will limit the transient voltage to no higher than 340V.

If the transient current is unknown, the graphical method of Figure 4.4 can be utilized. From a knowledge of the
transient voltage and source impedance a load line is plotted on the V-I characteristic. The intersection of the load line
with the varistor model curve gives the varistor transient current and the value of clamped peak transient voltage.

10000
8000

MAXIMUM CLAMPING VOLTAGE
COMPARED BY MODEL SIZE

~~I"I

= 130V RAT ING
TA := ·55 to .f-85°C

6000

5000

"-

4000

r\

3000

\

ULI499 CORD CONNECTED AND
DIRECT PLUG·IN CATEGORY "2000

~

g

.."ill
:E
:E

"

!i:E

1500

1000
V130LA2
V130LA5

800

l..1

600
500

-

400
300

V130LA IDA
V130LA20A

V

V

,./

V

200 I- IMPULSE GENERATOR LOAD UNES (IMPLIED)
UL 1449 PERMANENTLY CONNECTED CATEGORY,
I- AND ANSIIIEEE CSU1 (IEEE587) CATEGORY B
100
10'

111111111
10'

111111111
10'

111I11111

III

10'

PEAK AMPERES 8120,us WAVESHAPE

Figure 4.7 - Transient V-I Characteristics of Typical LA Series Models

The ability of the varistor to limit the transient voltage is sometimes expressed in terms of a clamp ratio. For example,
consider a varistor applied to protecting the power terminals of electrical equipment. If high line conditions will allow a
rise to 130V ac, then 184V peak would be applied. The device selected would require a voltage rating of 130V ac or
higher. Assume selection of a V130LA2 model varistor. The V130LA2 will limit transient voltages to 340V at currents of
lOA. The clamp ratio is calculated to be,
Clamp Ratio

Vc @ lOA

Peak Voltage Applied

= 340V = 1.85
184V

4-6

The clamp ratio can be found for other currents, of course, by reference to the V-I characteristic. In general, clamping
ability will be better as the varistor physical size and energy level increases. This is illustrated in Figure 4.8 which compares the clamping performance of the different Harris Varistor families. It can be seen that the lowest clamping voltages
are obtained from the 20mm (LA series) and 60mm (BA series) products. In addition, many varistor models are available
with two clamping selections, designated by an A, B, or C at the end of the model number. The A selection is the standard
model, with B and C selections providing progressively tighter clamping voltage. For example, the VI30LA20A voltage
clamping limit is 340V at lOOA, while the VI 30LA20B clamps at not more than 325Y.
1000

..'.'

~

MA4.

600

--

/ILA4/

./

500

.-"

~

....-""""

300

~

1'- ~

./

././
fo"""'"-""""

LA10',I
PA, LA20
BA
I
I
NOTE: CLAMP RATIO EQUALS VARISTOR VOLTAGE DIVIDED
BY VNOM OR 184V FOR 130VAC RMS

,!

~
100
0.01

0.05 0.1

0.5 1.0
5 10
50 100
INSTANTANEOUS CURRENT (A)

500 1K

5K 10K

Figure 4.8 - Varistor VI Characteristics for Four Product Families Rated at 130VAC
4.1.6 Summary
The five major considerations for varistor selection have been described. The final choice of model is a balance of these
factors with a device cost trade-off. In some applications a priority requirement such as clamp voltage or energy capability
may be so important as to force the selection to a particular model. A summary of varistor properties is provided in Figure
4.9 for a quick comparison of operating ranges.

J:

I-

§~

(!I

0

Zl-

...

>-

:o:Z

CI

w~!!.

w:2.
Z
w

cW~

...

~
(J

-en
Z
(!I a:

MAXIMUM STEADY·STATE APPLIED VOLTAGE

a:~

VOLTSACRMS
4 10 25

150
130

264
250 275

460

660 750

1,000

6,000

VOLTS DC
3.5 14 35

200
175

365
330 369

615

850 970

1,200

7,000

--

DlSCSIZESI
PACKAGES

80 500

0.5 - 5.0

150 1000

0.2- 25

40 ·100

0.07 1.7

25 ·4500

0.1 - 35

5,7,10,
14,20 (mm)

~~

0.4 -160

5x8,10x16,
14 x22 (mm)

flfiJfiJ

11 - 360

7,10,14,
20 (mm)

~~

6500

70 - 250

20mm

b

25,000 40,000

2701,050

50,000 70,000

450·
10,000

60mm

20,000 100,000

20010,000

32,40,42'8
52,60
(mm)

100 - 6500
1,200 9000

22,20,
16 GAUGE
1206
1210
5x8
1812
2220
3mm

Figure 4.9 - Varistor Product Family Selection Guide

4-7

~

-==-»--

34mm*.
SQ.~

(i;~
w

c

4.2 FAILURE MODES AND VARISTOR PROTECTION
Varistors are inherently rugged and are conservatively rated. Therefore, they exhibit a low failure rate. Nevertheless, the
careful designer may wish to plan for potential failure modes and the resultant effects on circuitry being protected.
4.2.1 Failure Modes
Varistors initially fail in a short-circuit mode when subjected to surges beyond their peak current!energy ratings. They
also short-circuit when operated at steady-state voltages well beyond their voltage ratings. This latter mode of stress may
result in the eventual open-circuiting of the device due to melting of the lead solder joint.
When the device fails in the shorted mode the current through the varistor becomes limited mainly by the source
impedance. Consequently, a large amount of energy can be introduced, causing mechanical rupture of the package
accompanied by expulsion of package material in both solid and gaseous forms. Steps may be taken to minimize this
potential hazard by the following techniques: I) fusing the varistor to limit high fault currents, and, 2) protecting the
surrounding circuitry by physical shielding, or by locating the varistor away from other components.

4.2.2 Fusing the Varistor
Varistor fusing should be coordinated to select a fuse that limits current below the level where varistor package damage
could occur. The location of the fuse may be in the distribution line to the circuit or it may be in series with the varistor as
shown in Figure 4.10. Generally, fuse rather than breaker protection is preferred. Breaker tripping is too slow to prevent
excessive fault energy from being applied.

r-----l

cr---_---III-I
I
I
I PROTECTED
I CIRCUIT
I
I

I

I
I
I
I
I
I

I
I

I

o-------~--~I-i
L _____ J

Figure 4.10 - Fuse Placement for Varistor Protection
In high power industrial circuits the line currents are generally so high as to rule out the use of a line fuse for varistor
protection. The fuse may not clear under a varistor fault condition and would allow varistor failure. In low power (S-20A)
applications it may be feasible to use the line fuse, FL, only.
Use of a line fuse, FL, rather than Fv, does not present the problem of having the fuse arc voltage being applied across the
circuit. Conversely, with Fv alone, the fuse arc voltage adds to the varistor voltage, increasing the Vc' the transient clamp
voltage. Since some fuses can have peak arc voltages in excess of twice peak working voltage, fuse clearing can have a
significant effect on protection levels.
Another factor in the choice of location is the consequence of system interruption. Fuse location FL will cause a
shutdown of the circuit while location Fv will not. While the circuit can continue to operate when Fv clears, protection no
longer is present. For this reason it is desirable to be able to monitor the condition of Fv.

4.2.3 Fusing Example (Light Industrial Application)
A process control minicomputer is to be protected from transients on a IISV nominal line. The minicomputer draws
7.5A from the line, which is guaranteed to be regulated to ±1O% of nominal line voltage. A V130LA20A varistor is
chosen on the basis that the worst-case surge current would be a 10/ I OOOps pulse of 100A peak amplitude. The rationale
for this surge requirement is that the incoming plant distribution system is protected with lightning arrestors having a
maximum arrestor voltage of SkV. Assuming a tyicalSOO characteristic line impedance, the worst-case transient current
through the varistor is 100A. The Irns impulse duration is taken as a worst-case composite wave estimate. While lightning
stroke discharges are typically less than lOOps, they can recur in rapid fire order during a Is duration. From the pulse
lifetime rating curves of the L series size 20 models, it is seen that the V130LA20 single pulse withstand capability at Ims
impulse duration is slightly in excess of 100A.

4-8

This is adequate for application in areas where lightning activity is medium to light. For heavy lightning activity areas,
either a DA or DB series varistor might be desirable to allow a capability of withstanding over 70 transients. In
making the choice between the LA series and higher energy series, the designer must decide on the likelihood
of a worst-case lightning stroke and the cost of the fuse replacement should the varistor fail.
Assuming a low lightning activity area, the VI30LA20A series is a reasonable choice. To coordinate the fuse with the
varistor, the single pulse lifetime curve is redrawn as Pt vs. impulse duration as shown in Figure 4.11. The Pt of the
composite 1O/IOOOIlS impulse is found from: 1

when:

where:

J2t =

31

-

-

T(.5);;::

200118 (time for impulse current to decay by 0.5)

Pt "'"

0.722

12 (lOllS) + 0.722 12

lOllS)

(T(.5) -

£2 T(.5)

the first term represents the impulse Pt contributed by the lOllS rise portion of the waveform and the second
term is the J2t contributed by the exponential decay portion.

""

~ '\

1000

~

~

V>

0

z

a

u

V>

0
UJ

."
0

100

V>

'\.
~

'\

0:

V>

~

"'\

UJ

'\

~ 1"\

~~
.x

0:

'\

...

UJ
0.

'"

'Q( k"'-

'\.

UJ

,,~ ~

'<;r§

i:
12 AMP

10

""'"

FUS~~

1
.1

PT. 2

."'\.

~

~~
T\.

I

I

lOlLS

IOOf'S

[I..-

I~

I
PT.(
"ASSUMED WORST CASE

I

MAX. CLEARING J2 t
I2 AMPERE FUSE
MI N. MELTING J2 t

"\.

T~ANSIEINT 11211

I

lm~

IMPULSE DURATION- SECONDS

I

'< ~

""

I

PACKAGE RUPTURE
POSSIBLE PACKAGE RUPTURE
DEVICE FAILURE

DEVICE
~ ?5++- POSSIBLE
(SHORT CIRCUIT)

~L

'\

a-r-

FAILURE

SINGLE PULSE LIFETIME RATING.
J 2t (VI30LA20)

IOms

Figure 4.11 - Harris Varistor - Fuse Coordination Chart
Figure 4.11 shows a cross-hatched area which represents the locus of possible failure of the varistor. This area is equal to
an J2 value of from two to four times that derived from the data sheet peak current pulse life curves. The curve extending
beyond the cross-hatched area and parallel to it is where package rupture will take place.
The criteria for fuse selection is given below.
A) Fuse melts; i.e., opens, only if worst-case transient is exceeded and/or varistor fails.
B) If varistor fails, fuse clearing limits Pt applied to varistor values below that required for package rupture.
C) Fuse is rated at l30V RMS.
D) Fuse provides current limiting for solid-state devices.

4-9

Based on the above, a Carbone-Ferraz 12A RMS, l30VRMS, Class FA fuse is tentatively selected. The minimum
melting Pt and maximum clearing Ft curves for the 12A fuse are shown superimposed on the varistor characteristics.
This fuse is guaranteed to melt at an J2t of 40% above the estimated worst-case transient. Upon melting, clearing Pt and
clearing time will depend upon available fault current from the l30V RMS line. Figure 4.12 lists clearing times for the
selected fuse versus available prospective circuit current.
Prospective Current
AmpsRMS

Clearing Time
Milliseconds

60

8.0

120

5.6

240

3.5

1200

1.3

3600

0.57

Figure 4.12 - 12A Fuse - Prospective Current vs. Clearing Time

As Figure 4.11 shows, a clearing time ofless than l.5ms is desirable. For fault currents in excess of 1.2kA, the fuse will
clear at less than 24A 2s and 1.3ms. This will prevent varistor package rupturing. However, the distribution line may be
"soft," i.e., have a high source impedance at the 60Hz power frequency that limits the fault currentto values below l.2kA.
Then, it is possible that the fuse would not protect the varistor package from rupturing, though it would serve to isolate the
varistor in any case.
Upon further examination of this example, it is clear that the varistor will be protected from package rupturing even if
the transient pulse current is 50% greater than that of the assumed value, resulting in an Pt of 16A2s (Point 2 on
Figure 4.11).
Placement of the fuse for this example application could be in the line or in series with the varistor. If in series with the
varistor, the line fuse should be a medium to slow speed, such as a "slow blow" type 15A fuse. That would assure a fault in
the varistor would be isolated by the varistor fuse without interrupting the line fuse.
It is desirable to indicate the status of the varistor fuse if one is used in addition to the line fuse. The circuit shown in
Figure 4.13 senses the presence of voltage across t9-e varistor by use of a photocoupler. When the fuse interrupts the
varistor circuit, the LED of the coupler becomes de-energized, and the coupler output signal can be used to annunciate an
unprotected condition. Some fuse manufacturers provide indicating means upon fuse operation that may also be used to
trip an alarm.

HI1AA2

12k AC

130V
AC

2W
___ _
I

I

OPTO~COUPLER}
_
~ "

I

r~-"

TO STATUS
ANNUNCIATOR
LIGHT / ALARM

TO
PROTECTED
CIRCUIT

I

I

1_ _ _ _ _ _

1

--.1

Figure 4.13 - Varistor Fuse Status Sensing Circuit

In selecting a fuse, the reader is advised to avoid data based on average values or data taken at operating conditions that
are grossly different from the actual application. For example, dc data does not apply when the fuse will be used on an ac
circuit. Also, test data taken in a resistive circuit with unity power factor does not hold for low power factor operation.

4-10

4.3 SERIES AND PARALLEL OPERATION OF VARISTORS
In most cases the designer can select a varistor that meets the desired voltage ratings from standard catalog models.
Occasionally the standard catalog models do not fit the requirements either due to voltage ratings or energy! current
ratings. When this happens, two options are available: varistors can be arranged in series or parallel to make up the desired
ratings, or the factory can be asked to produce a "special" to meet the unique application requirement.

4.3.1 Series Operation of Varistors
Varistors are applied in series for one of two reasons: to prO\;ide voltage ratings in excess of those available, or to
provide a voltage rating between the standard model voltages. As a side benefit, higher energy ratings can be achieved
with series connected varistors over an equivalent single device. For instance, assume the application calls for a lead
mounted varistor with an RMS voltage rating of 375V ac and having a I tm peak current capability of 6000A. The I tm
requirement fixes the varistor size. Examining the LA series voltage ratings near 375V ac, only 320V and 420V units are
available. The 320V is too low and the 420V unit (V420LA40B) results in too high a clamp voltage (Vc of 1060V at
100A). For a V130LA20B and a V250LA40B in series, the maximum rated voltage is now the sum of the voltages, or
380V. The clamping voltage, Vo is now the sum of the individual varistor clamping voltages, or 945V at 100A. The peak
current capability is still 6500A but the energy rating is now the sum of the individual energy ratings, or 200J.
In summary, varistors can be connected in series providing they have identical peak current ratings (Itm), i.e., same disc
diameter. The composite V-I characteristic, energy rating, and maximum clamp voltages are all determined by summing
the respective characteristics and! or ratings of the individual varistors.

4.3.2 Parallel Operation of Varistors
Application requirements may necessitate higher peak currents and energy dissipation than the high
energy series of varistors can supply individually. When this occurs, the logical alternative is to examine the
possibility of paralleling varistors. Fortunately, all Harris Varistors have a property at high current levels that
makes paralleling feasible. This property is the varistor's series-resistance that is prominent during the
"up-turn region" of the V-I characteristic. This up-turn is due to the inherent linear resistance component of
the varistor characteristic (see Chapter 3). It acts as a series balancing, or ballasting, impedance to force a
degree sharing that is not possible at lower current levels. This is depicted in Figure 4.14. At a clamp voltage of
600V, the difference in current between a maximum specified sample unit and a hypothetical 20% lower
bound sample would be more than 20 to 1. Thus, there is almost no current sharing and only a single varistor
carries the current. Of course, at low current levels in the range of 10-100A, this may well be acceptable .
...-'

1000

'"e!

(-LIMIT SAMPLE

800

l-

~

w
(!)

~

<5

>

'"

~

a.

600

f-

- --

/

500

400
~LOWER

100
0.1

,..- I-- I--' ~

BOUND 120%)

SAMPLE UNIT

300
200

....-::: ;......-

raT rr
.5

I

I I
.1 .1.

IB~J

MODEL V251 BA60

II I I I

TO

5

10

50 100

500 1000

500010.000

PEAK CURRENT - AMPERES

Figure 4.14 - Parallel Operation of Varistors by Graphical Technique
At high current levels exceeding 1000A, the up-turn region is reached and current sharing improves markedly. For
instance, at a clamp voltage of900V, the respective varistor currents (Figure 4.14) are 2500A and 6000A, respectively.
While far from ideal sharing, this illustration shows the feasibility of paralleling to achieve higher currents and energy than
achievable with a single model varistor.

4-11

Practically, varistors must be matched by means of high current pulse tests to make parallel operation feasible. Pulse testing should be in the range of over lkA, using an 812O!ts, or similar pulse. Peak voltages must be read and recorded. High
current characteristics could then be extrapolated in the range of l00-lO,OOOA. This is done by using the measured data
points to plot curves parallel to the data sheet curves. With this technique current sharing can be considerable improved
from the near worst-case conditions of the hypothetical example given in Figure 4.14.
In summary, varistors can be paralleled, but good current sharing is only possible if the devices are matched
over the total range of the voltage-current characteristic. In applications requiring paralleling, Harris should
be consulted.
Some guidelines for series and parallel operation of varistors are given in Figure 4.15.
Series

Objective

Parallel

Higher Voltage Capability
Higher Energy Capability
Non-standard Voltage Capability

Selection Required

Higher Current Capability
Higher Energy Capability

NO

YES

Models Applicable

All, must have same Itm rating.

All models

Application Range

All voltages and currents.

All voltages - only high currents,
i.e., > 100 amperes.

Precautions

Itm ratings must be equal.

Must be identical voltage rated models.
Must test and select units for similar
V-I characteristics.

Effect on Ratings

Clamp voltages additive.
Voltage ratings additive.
Current ratings that of single device.

Current ratings function of current
sharing as determined graphically.
Energy ratings as above in proportion
to current sharing.
Clamp voltages determined by composite V-I characteristic of matched
units.
Voltage ratings that of single unit.

Energy Wtm , ratings additive.

Figure 4.15 - Checklist for Series and Parallel Operation of Varistors

4.4 APPLICATIONS
4.4.1 Power Supply Protection Against Line Transient Damage
PROBLEM: It is desired to prevent failure of the power supply shown in Figure 4.16(b) to be used on residentiall17V
ac lines. A representative transient generator is to be used for testing, as shown in Figure 4.l6(a).
500
I

VT

"v-

=

O.il'-f8

! 5kV sin 10 5 " t X

I

e- IO- 5t

(bl Typical Power Supply Circuit

(a) Transient Generator

Figure 4.16 - Power Supply Protection

4-12

lethe transient is applied to the existing circuit, the rectifier will receive high negative voltages, transmitted through the
filter capacitor. The LC network is there to prevent RFI from being transmitted into the power line (as in a TV set), but
also serves to reduce the transient voltage. An analysis shows that the transient will be reduced approximately by half,
resulting in about 2.5kV instead of 5kV at the rectifier.
This is still too high for any practical rectifier, so some suppression must be added. It is desirable to use the built-in
impedance of the coil to drop the remaining voltage, so the suppressor would best be applied as shown. A selection process
for a Harris Varistor is as follows:
SOLUTION:
Steady-State Voltage
The 117V ac, 11 0% high line condition is 129V. The closest voltage rating available is 130V.
Energy and Current
The 100J.lH inductor will appear to be about 300 to the transient. The 300 is derived from the inductive reactance at
the transient generator source frequency of 105 7T rad. Taking a first estimate of peak varistor current, 2500V ISOO = 31 A.
(This first estimate is high, since it assumes varistor clamping voltage is zero.) With a tentative selection of a 130V
Harris Varistor, we find that a current of31A yields a voltage of from 325V to 430V, depending on the model
size, as shown in Figure 4.17.

JI

3000 r--.-T--rrcnrr----,-rTTTnn-~_n_~cm_'\~~~
UL1499 CORD CONNECTED AND
DIRECT

~

PLUG~IN

CATEGOR, Y,.........

iiiI
~

:J

~

:!;

I' ,

1

2000 r--H--t+t+ttt-t-t+H+t+t---i~+-t+t1'ttt--t--t-t--tttti
1500 I--t-t-t+ftttt---i-t-!'+tt'tttt---t_H
,\r f-'Ift'fttt---Il-t-fttt-Ht
I

i

1000
800
(/)

I

~600

1000 f--++t++t1-tt--+++++,tfit-++Ht-fiiVl+-30-L-+A2-tt-14rtt,-H1
800 1--t-t-t+ftttt---"rt+tttttt---t-+lHtrtW~V130LA5
600
500 rrt-t-t+ftttt---,rtffitttt-~>"f-Htt~VA*fttt-Ht
I,

400 -

-

--

Il.

:;

~ IMPULi~ dENERATJ~ 15 (IMPLI~ll;1
~-nHiElirTll1irfTmillll
II
10'-,'"' 27..1 t/

~

10'

\

10'

,

~
~

r::::

,
I
I

200

LOAD

10'

--- I--:: I--

:;

UL1449 PERMANENTLY CONNECTED CATEGORY, AND

..... 31

400 - --

"~300

i

:::

V

~I

V

~

......

V

> 500

f---bl-fI'"Fmf=I~+++tfit--t+H.lfHi+7'4I1*H"Vl.e~~~~~~OA
/"

/'

,

/

I
I
I

V

~

100~

10 '

2~31

10'

PEAK AMPERES 8/2011$ WAVE$HAPE

PEAK AMPERES 8/20JiS WAVESHAPE

Figure 4.17 - VI30LA Varistor V-I Characteristics

Revising the estimate, I = (2500V - 325V)/SOO = 27.2A. For model V130LA20B, 27.2A coincides closely with a
320V clamping level. There is no need to further refine the estimate of peak current if model B remains the final selection.
To arrive at an energy figure, assume a sawtooth current waveform of 27 A peak, dropping to zero in two time
constants, or 20J.ls.
f-

Iv

Z

Iv

"'27-

27

u



ii:

':!

Figure 4.18 - Energy Approximation

4-13

Energy is then roughly equal to (27 A x 320V x 20Jls)l2, the area under the power waveform. The result is 0.086J, well
within the capability of the varistor (50J). Peak current is also within the 6000A rating.

Model Selection
The actual varistor selection is a trade-off between the clamping voltage desired and the number of transient current
pulses expected in the life of the equipment. A 50J rated varistor will clamp at 315V and be capable of handling over 105
such pulses. An 8J unit will clamp to approximately 385V and be capable of handling over 1000 such pulses.
Furthermore, the clamping voltage determines the cost of the rectifier by determining the voltage rating required. A
smaller, lower cost varistor may result in a more expensive higher voltage rectifier diode.

4.4.2 SCR Motor Control

:-l
A:J

R,
330kU

FIELD
SCR

4'1

Figure 4.19 - SCR Motor Control
PROBLEM: The circuit shown in Figure 4.19 experiences failures ofthe rectifiers and SCR when the transformer
primary is switched off. The manufacturer has tried 600V components with little improvement.
SOLUTION: Add a varistor to the transformer secondary to clamp the transformer inductive transient voltage spike.
Select the lowest voltage Harris Varistor that is equal to or greater than the maximum high line secondary ac
voltage. The V130LA series fulfills this requirement.
Determine the peak suppressed transient voltage produced by the transient energy source. This is based on the peak
transient current to the suppressor, assuming the worst-case condition of zero load current. Zero load current is normally a
valid assumption. Since the dynamic transient impedance of the Harris Varistor is generally quite low, the
parallel higher impedance load path can be neglected.

Determination of Peak Transient Current
Since transient current is the result of stored energy in the core of the transformer, the transformer equivalent circuit
shown in Figure 4.20 will be helpful for analysis. The stored inductive energy is:

1

"-

EL =- Lm Pm
m

2

r - - - Z p----,

f

IMARY

i

MUTUA'
INDUCTANCE
REPRESENTED

II

J+

1m

I

'm

BY IRON CORE

1

r

~IO~'

IDEAL

TRANSFORMER

Figure 4.20 - Simplified Equivalent Circuit of a Transformer

4-14

The designer needs to know the total energy stored and the peak current transformed in the secondary circuit due to the
mutual inductance, Lm' At no load, the magnetizing current, (INL)' is essentially reactive and is equal to im. This assumes
that the primary copper resistance, leakage reactance and equivalent core resistive loss components are small compared to
Lm' This is a valid assumption for all but the smallest control transformers. Since INL is assumed purely reactive, then:
Vpri

XLM

INL

and
im
INL
INL can be determined from nameplate data. Where nameplate is not available, Figures 4.21 and 4.22 can guide the
designer.

14
2
0

\

8

r--f '" 50 ._. 60Hz

-10

12

TRANSFORMER RATING - kVA

Figure 4.21 - Magnetizing Current of Transformers with Low Silicon Steel Core

"'-

~

Ii!0:

""C!J
z

5

r-....

4

N

~ 3
z

'---

i"'5Q ... 60Hz

~

......

:;; 2
fZ
W

"

ffiCL

1
10

102
TRANSFORMER RATING - kVA

103

10'

Figure 4.22 - Magnetizing Current of Transformers with High Silicon Steel Core
or Square Loop Core

4-15

Assuming a 3.5% value of magnetizing current from Figure 4.22 for a 20kVA transformer with 480V ac primary, and
120V ac secondary:
im

= (0.035)

20kVA
480V

1.46A
im

XLm
Lm

Elm

=
=
=
=
=
=
=

v'2im
480VIl.46A
3290

XLiw
0.872H
0.872 (2.06)2
2
1.85J

With this information one can select the needt'Ai semiconductor voltage ratings and required varistor energy rating.
Semiconductor Blocking Voltage Ratings Required

•

Peak varistor current is equal to transformed secondary magnetizing current, i.e., im(N), or 8.24A. From Figure 4.17,
the peak suppressed transient voltage is 310V with the V130LAlOA selection, 295V with the V130LA20B. This allows
the use of 300V rated semiconductors. Safety margins exist in the above approach as a result of the following assumptions:
I. All of the energy available in the mutual inductance is transferred to the varistor. Because of core hysteresis and
secondary winding capacitance, only a fraction less than two-thirds is available.
2. The exciting current is not purely reactive. There is a 10% to 20% safety margin in the peak current assumption.
After determining voltage and peak current, energy and power dissipation requirements must be checked. For the given
example, the single pulse energy is well below the V130LAIOA varistor rating of 38J at 85°C maximum ambient
temperature. Average power dissipation requirements over idling power are not needed because of the non-repetitive
nature of the expected transient. Should the transient be repetitive, then the average power is calculated from the product
of the repetition rate times the energy of the transient. If this value exceeds the V130LA20A capability of 1.0W, power
varistors of the HA, DA, or DB Series.

Should the ambient temperature exceed 85 0 C or the surface temperature exceed 85 °C, the RA series varistors should
be considered because of their higher temperature capabilities. The single pulse energy ratings and the average power
ratings must be derated by the appropriate derating factors supplied on the data sheet.

4.4.3 Contact Arcing Due to Inductive Load
When relays or mechanical switches are used to control inductive loads, it is necessary to use the contacts at only about
50% of their resistive load current rating to reduce the wear caused by arcing of the contacts. The energy in the arcing is
proportional to the inductance and to the square of the current.
Each time the current in the inductive load is interrupted by the mechanical contacts, the voltage across the contacts
builds up as - L dil dt. When the contacts arc, the voltage across the arc decreases and the current in the coil can increase
somewhat. The extinguishing of the arc causes an additional voltage transient which can again cause the contacts to arc. It
is not unusual for the restriking to occur several times with the total energy in the arc several times that which was
originally stored in the inductive load. It is this repetitive arcing that is so destructive to the contacts.

4-16

PROBLEM: To extend the life of the relay contacts shown in Figure 4.23 and reduce radiated noise, it is desired to
eliminate the contact arcing.

r---------..,I RELAY
I
I

Cc

STRAY CAPACITANCE

L

RELAY COIL INDUCTANCE

Rc

RELAY COIL RESISTANCE

28V
DC

L _________ _

Figure 4.23 - Relay Circuit

In the example, Rc is 300 and the relay contacts are conducting nearly IA. The contacts will draw an arc upon opening
with more than approximately O.4A or 12V. The arc continues until current falls below 0.4A.
SOLUTION: To prevent initiation ofthe arc, it is necessary to reduce the current and voltage ofthe contacts below the
arc threshold levels at the time of opening, and then keep them below breakdown threshold of the contacts as they open.
Two obvious techniques come to mind to accomplish this: I) use of a large capacitor across the contacts, and 2) a voltage
clamp (such as a varistor). The clamp technique can be effective only when the minimum arc voltage exceeds the supply
voltage.

In this example a clamping device operating above the supply voltage will not prevent arcing. This is shown in
Figure 4.24.

:r:

I-

~~

Cl~

~(/)

zClO::

1ii~
c

w

VOLTAGE CLAMP ABOVE
ARC VOLTAGE
VOLTAGE CLAMP BELOW
ARC VOLTAGE

U

0:

"

O+------r-----+----~------T__.

o

75

50

25

100

BREAK TIME - MICROSECONDS

Figure 4.24 - Voltage Clamp Used as Arc Suppressor

The capacitor technique requires the capacitance to be sufficiently large to conduct the inductor current with a voltage
rate-of-rise tracking the breakdown voltage rate-of-rise of the contacts as they mechanically move apart. This is shown in
Figure 4.2S(a).
",100

(f)

'o:J

':J

w

w

>,

~ 50

~ 50

""o

""

..J

..J

o
>

SMALL C WITH R
(ARCING)

>

0:

SMALL C WITH RAND
VOLTAGE CLAMP COMBINATION

U
0:

U

"

100

~,

BREAK TIME - MICROSECONDS

0+-----4r-----+----~------r_-+
75
100
25
50
o
BREAK TIME - MICROSECONDS

(a) R-C Arc Suppression

(b) R-C & Clamp Arc Suppression

0+-----4r-----r----~------r+

o

25

50

75

100

"

Figure 4.25 - Relay Arc Voltage Suppression Techniques

4-17

The limitations in using the capacitor approach are size and cost-This is particularly true for those cases involving large
amounts of inductive stored energy. Furthermore, the use of a large capacitor alone creates large discharge currents upon
contact reclosure during contact bouncing. As a result, the contact material may melt at the point of contact with
subsequent welding. To avoid this inrush current, it is customary to add a series resistor to limit the capacitive discharge
current. However, this additional component reduces the network effectiveness and adds additional cost to the solution.
A third technique, while not as obvious as the previous two, is to use a combination approach. This technique shown in
Figure 4.25(b) parallels a voltage clamp component with an R-C network. This allows the R-C network to prevent the
low voltage initial arcing and the clamp to prevent the arcing that would occur later in time as the capacitor voltage builds
up. This approach is often more cost effective and reliable then using a large capacitor.
Also, with ac power relays the impedance of a single large R-C suppressor might be so low that it would allow too much
current to flow when the contacts are open. The combination technique of a small R-C network in conjunction with a
varistor is of advantage here, too.
In this example a 0.22J.lF capacitor and 100 resistor will suppress arcing completely, but by reducing the capacitance to
0.047J.lF, arcing will start at 70V.
Thus, to use a varistor as a clamp in conjunction with the R-C network, it must suppress the voltage to below 70V at lA
and be capable of operating at a steady-state maximum dc voltage of 28V + 10%, or 30.8V (assumes a ± 10% regulated
28V dc supply).
Selecting the Varistor

The three candidates that come closest to meeting the above requirement are the MA series V39MA2B model and the
ZA series V39ZAl and V39ZA05 models, all of which have maximum steady-state dc voltage ratings of 31 V. The
V39MA2B and V39ZA05 V-I characteristics at lA shows a maximum voltage of 73V, while the V39ZAl characteristic
at lA shows a maximum voltage of 67V. Thus, the latter varistor is selected. Use of a 0.068J.lF capacitor in place of the
0.047J.lF previously chosen would allow use of the V39MA2B or V39ZA05.
Placing only a Harris Varistor rated for 3lV dc across the contacts results in arcing up to the 66V level. By
combining the two, the capacitor size and voltage rating are reduced and suppression complete.
Besides checking the varistor voltage and arcing elimination, the designer should review energy and peak current
requirements. Varistor energy is determined from a measurement of the coil inductance and the calculation E = ~ Li2.
Peak current, of course, is under IA. Power dissipation is negligible unless the coil is switched often (several times per
minute).
In those cases where multiple arcs occur, the varistor energy will be a multiple of the above ~ Lil value. The peak
current is well within the rating of either the MA or ZA series of varistors, but the number of contact operations allowable
for either varistor is a function of the impulse duration. This can be estimated by assuming a LIRe time constant at the lA
or peak current value. Since the voltage across the varistor is 67V at lA, the varistor static resistance is 670. The coil Re
value is 28V /lA, or 280. The coil inductance was found to be 20mH. Thus, the approximate time constant is:
T

20mH
95

= 21OJ.ls

From the pulse lifetime curves of the V39ZAI model, the number of allowable pulses exceeds 100 million.

4.4.4 Noise Suppression
Noise is an electromechanical system is a commonly experienced result of interrupting current by mechanical contacts.
When the switch contacts open, a hot cathode arc may occur if the current is high enough. On the other hand, low current
will permit switch opening without an arc, but with ringing of circuit resonances. As a consequence, voltages can exceed
the contact gap breakdown resulting in a replica of the old spark gap transmitter. It is the low current case that produces
the most serious noise disturbances which can result in malfunctions or damage to electrical equipment. These pulses
cause noise problems on adjacent lines, trigger SCR's and triacs, and damage semiconductors. In addition, they can raise
havoc with mircroprocessor operation causing memory to be lost and vital instructions to be missed.

4-18

PROBLEM: Switching of a small timer motor on 120V, 60Hz, was causing serious malfunctions of an electronic
device operating from the same power line. Attempts were made to observe the transient noise on the line with an
oscilloscope as the first step in curing the problem. Observed waveforms were "hash," i.e., not readily identifiable.
SOLUTION: A test circuit (Figure 4.26) was set up with lumped elements replacing the measured circuit values. The
motor impedance was simulated by Rp LI, and C I, and the ac line impedance by L2 and C2. A dc source allowed
repeatable observations over the full range of current that could flow through the switch in the normal ac operation. A
diode detector was used to observe the RF voltage developed across a 2" length of wire (50nH of inductance).
L2

5p.H

,- --,

SI

J

+
Vee

VI

I
I
I
I
I
CI
I
SOpF :

I

I
I
IG.8H
I
I
I
: 144Sn
I

_...J

V.F

I
Figure 4.26 - Test Circuit
The supply is set at 25mA to represent the peak motor current in normal120V ac operation. As switch SI was opened,
the waveform in Figure 4.27 was recorded. Note the "showering arc" effect. The highest breakdown voltage recorded
here is 1020V, and the highest RF detector output (shown in the lower trace) is 32V.
Obviously, some corrective action should be taken and the most effective one is that which prevents the repeated
breakdown of the gap. Figure 4.28 shows the waveform of VI (upper trace) and VRF (lower trace) for the same test
conditions with a Harris Varistor, type V130LAIOA, connected directly across the switch terminals. The
varistor completely eliminates the relaxation oscillations by holding the voltage below the gap breakdown
voltage (about 300V) while dissipating the stored energy in the system.

II

I,

P4

200V/em

10V/cm

m

200ps/em
Upper
V 1:
Lower V RF:
t:

200 V fem
20 V/cm

Lower V RF :
t:

20V/em

O.2ms/cm

O.2ms/crn

Figure 4.27 - Unprotected Contacts

Figure 4.28 -

4-19

Varistor Protected Contacts

4.4.5 Protection of Transistors Switching Inductive Loads
PROBLEM: The transistor in Figure 4.29 is to operate a solenoid. It may operate as frequently as once per second. The
circuit (without any suppression) consistently damages the transistor.

VClh-

V+
26V

Yc

Ie

V+
26V

1

t

I

I

:

1

1

I

I

I

I

470
OHMS

Vc • COLLECTOREMITTER
VC6j;:oLTAGE

I
I
I

I

~Iv

I

I
I
I

Ie

I
I

I

I
I

I[
I I

1

1

I

I

t

IV

I

'---'

PERIOD OF HIGH SOA
REQUIREMENT

(a) Basic Solenoid Circuit

(b) Solenoid Circuit with Varistor Protection

Figure 4.29 - Transistor Switching of an Inductive Load

The inductor drives the collector voltage up when the transistor base is grounded (turning "off'). The inductor forces
current to flow until the energy stored in its field is dissipated. This energy is dissipated in the reverse bias condition of the
transistor and is sufficient to cause breakdown (indicated by a sudden collapse of collector voltage during the pulse).
SOLUTION: This condition can be eliminated either by shunting the transistor with a suppressor or by turning it on
with a varistor connected collector-to-base. The first method will considerably reduce the demands upon the safeoperating area (SOA) of the transistor. Ifthe voltage is kept below its breakdown level, all energy will be dissipated in the
suppressor. The latter method will cause the transistor to once again dissipate the stored energy, but in the forward-bias
state in which the transistor can safely dissipate limited amounts of energy. The choice is determined by economics and
reliability. A suppressor connected collector-emitter (C-E) will be more expensive than one connected C-B, since it is
required to absorb more energy, but will allow the use of a transistor with reduced SOA.
If a collector-emitter varistor is used in the above example, it is required to withstand 28.6V dc worst-case (26 + 10%
regulation). The stored energy is lh Li2 or lh (0.20) (0.572)2 = 0.0327J. The energy contributed by the power supply is
roughly equal to this (coil voltage = supply voltage, since varistor clipping voltage = 2 x supply voltage). Ignoring coil
resistance losses for a conservative estimate, varistor energy dissipation is 0.065J per pulse. The peak current will be
0.572A, the same as the coil current when the transistor is switched off.

If the transistor operates once per second, the average power dissipation in the varistor will be 0.065W. This is less than
the 0.20W rating of a small 31 V dc varistor (V39ZA I). From the data sheet it can be seen that if the device temperature
exceeds 85°C, derating is required. The non-recurrent joule rating is 1.2J, well in excess of the recurrent value. To
determine the repetitive joule capability, the current pulse rating curves for the ZA series must be consulted. Two are
shown in Figure 4.30.
To use Figure 4.30, the impulse duration (to the 50% point) is estimated from the circuit time constants and is found to
be 1240J.ls. From Figure 4.30(a), the pulse rating is estimated to be slightly over 108 operations. As this may not be
adequate, the designer may wish to go to a larger size varistor (V39ZA6). At 0.572A, the approximate impulse duration is
now found to be I 280J.ls and using Figure 4.30(b), the designer is faced with the problem of extrapolation below lA. This
has been done in Figure 4.31 which is a new plot of the data of Figure 4.30(b) at 1280J.ls.
We conclude that the life exceeds 109 operations. The reader may question the extrapolation of four orders of
magnitude. At low currents the relationship is a straight line extrapolation on log-log paper, as seen from Figure 4.30(a),
where the pulse rating curves extend to 108 pulses.
The clipping characteristics of the V39ZA6 model will provide a 61 V maximum peak. The transistor should have a
VCER of 65V or greater for this application.

4-20

500
200

,

1000

~

100

10

50

10'

20
10

...!2

MODEL SIZE 7mm
V18ZA1 - V68ZA2

500

r-..

20o

.....

3

~r-..

100

.......... r-.

r-

::::--.....

-

MODEL SIZE 14mm
V18ZA3 - V68ZA10

s;;J2
""'-.'0

.........

r-.

0 .:::- .....

~

~103

RO'

r- ........
F=::::-- .:::::-

o~

-

10'

INDEFINIT.

50

""..,

o

::--;;::::: E;::~

t----'I!gEF/""

.......... :--..

r::::-

r--

5

O. 5
O. 2 20

100

1000

100

10,000

IMPULSE DURATION - liS

1000
IMPULSE DURATION - liS

10,OGO

(b) - ZA Series V18ZA3 to V68ZAIO
Model Size 14mm

(a) - ZA Series V18ZAl to V68ZA2
Model Size 7mm

Figure 4.30 - ZA Series Pulse Ratings

15

10

:'.....
............

8

'--......


u

Vl8ZA3 TO VIOOZAI5

............

~ 5

~,

ZA SERIES

2

.....

w



"-

"- .....

a.

:s:
w I

"a.

..... .....

-NOTE:
PULSE RATING CURVE FOR 1,280 MICROSECONDS PULSE WIDTH

106

.....

.....

..........

107

NUMBER OF PULSES

Figure 4.31 - Extrapolated Pulse Rating Curves

4.4.6 Motor Protection
Frequently, the cause of motor failures can be traced to insulation breakdown ofthe motor windings. The source ofthe
transients causing the breakdown may be from either internal magnetic stored energy or from external sources. This
section deals with the self-generated motor transients due to motor starting and circuit breaker operation. Externallygenerated transients and their control are covered in Chapter 2.
In the case of dc motors the equivalent circuit consists of a single branch. The magnetic stored energy can be easily
calculated in the armature or field circuits using the nameplate motor constants. With ac induction motors the equivalent
magnetic motor circuit is more complex and the circuit constants are rarely given on the motor nameplate. To provide a
guide for motor protection, Figures 4.32, 4.33 and 4.34 were drawn from typical induction motor data. While the actual

4-21

stored energy will vary according to motor frame size and construction techniques, these curves provide guidance when
specific motor data is lacking. The data is conservative as it assumes maximum motor torque, a condition that is not the
typical running condition. Stored energy decreases considerably as the motor loading is reduced. Experience with the
suppression of magnetic energy stored in transformers indicates that Harris Varistors may be used at their
maximum energy ratings, even when multiple operations are required. This is because of the conservatism in
the application requirements, as indicated above, and in the varistor ratings. Thus, no attempt is made to
derate the varistor for multiple operation because of the random nature of the transient energy experienced.

600
Y CONNECTED

400

200

~:::J

Q
w

~

100

eo

J:

"-

0::

60

W

"-

>-

C!J

0::
W

40

Z

w
0

W

0::

0

t-

en

20

NOTES'
I. Y CONNECTED 60Hz
2. ENERGY AT MAX. TORQUE
SLIP SPEED

'-+--+-f-

--+--+----1

e~---+---+--~~-t----+---~---r-~
610~--~20~---4~0~~6~0~8~O~I~00~--~~--~~~6~070~8~0~0~1000
MOTOR HORSEPOWER

Figure 4.32 - Stored Energy Curves for Typical Wye-Connected Induction Motor

4-22

600
DELTA CONNECTED
400

200

'""j

:J

Q

100

w

80

Il.

60

~
x

ffi

Il.

>-

'zffi"

40

w
0
w
rr:

a

tii

20
NOTES'
I. DELTA CONNECTED@ 60 Hz
2. ENERGY AT MAX. TORQUE
SLIP SPEED

60
8 100
MOTOR HORSEPOWER

600 8001000

Figure 4.33 ..,... Stored Energy Curves for Typical Delta-Connected Induction Motor
600

/

400
MOTOIR STORED

E~ERGY IT

/ V
~/
,,7
Ar-#

S;ART

200

'""j
:J

Q

100

w

80

'"

«
x

Il.

ffi

...",0

230 VRMS
(LiNE-LINE)"

60

>-

40

w
0
w
a:

a

>-

'"

20

1L
jt

~"0-

4 2 a

/'
10

20

""'"'

NOTES
I 60 Hz SEE FIGURE 436
FOR VARISTOR CIRCUIT
2 ENERGY AT START
Ie SLIP:; 1
3 INDUCTION MOTOR

T~lj-O-

6

VRMS (LINE-LINE)

#'~~V

.,o-.

DELTA CONNECTED

APPLIEDV.
VARISTOR RATINGS

YCONNECTED

APPLIEDV.
VARISTOR RATINGS

230

380

460

550

600

230

380

460

550

600
660

220

266
320

2501275 420/480 510/575 575/660
133
150

2501275

318
420

346
420

Figure 4.35 - Preferred Varistor Voltage Ratings for
Delta- and Wye-Connected Motors
Interruption of motor starting currents presents special problems to the user as shown in Figure 4.34. Since the stored
magnetic energy values are approximately 10 times the running values, protection is difficult at the higher horsepower
levels. Often the motor is started by use of a reduced voltage which will substantially reduce the stored energy. A reduction
in starting current of a factor of two results in a four-fold reduction in stored energy. If a reduced voltage starter is not used,
then a decision must be made between protection for the run condition only, and the condition of locked rotor motor
current. For most applications, the starting condition can be ignored in favor of selecting the varistor for the worst-case run
condition.

I
VVARtSTOR = ,.,f3 VL- l

VVARtSTOR

= VL - L

(b) Delta Connected

(a) WYE Connected

Figure 4.36 - Varistor - 3cp Induction Motor Circuit Placement
PROBLEM: To protect a two-pole, 75hp, 3cp, 460V RMS line-to-line wye-connected motor from interruption of
running transients.
Specific motor data is not available.
SOLUTION: Consult Figure 4.32 along with Figure 4.35. Standard varistors having the required voltage ratings are
the 320V RMS rated models. This allows a 20% high-line voltage condition on the nominal 460V line-to-line voltage, or
266V line-neutral voltage. Figure 4.32 shows a two-pole 75hp, wye-connected induction motor, at the running condition,
has 52] of stored magnetic energy per phase. Either a V320PA40 series or a V321DA40 series varistor will meet
this requirement. The DA series Harris Varistor provides a greater margin of safety, although the PA series
Harris Varistor fully meets the application requirements. Three varistors are required, connected directly
across the motor terminals as shown in Figure 4.36 .

4-24

4.4.7 Power Supply Crowbar
Occasionally it is possible for a power supply to generate excessively high voltage. An accidental removal ofload can
cause damage to the rest of the circuit. A simple safeguard is to crowbar or short circuit the supply with an SCR. To
provide the triggering to the SCR, a high-voltage detector is needed. High voltage avalanche diodes are effective but
expensive. An axial leaded Harris Varistor provides an effective, inexpensive substitute.
PROBLEM: In the circuit below, the voltage, without protection, can exceed twice the normal 240V peaks, damaging
components downstream. A simple arrangement to crowbar the supply is shown.
The supply shown can provide 2A RMS of short-circuit current and has a 1A circuit breaker. A C106SCR having a 4A
RMS capability is chosen. Triggering will require at least O.4V gate-to-cathode, and no more than 0.8V at 200pA at 25°C
ambient.
I AMP C.B.

r---.

r-----~

o----~~~~

~,

CI06D
NORMAL VOLTAGE < 240V PEAK
ABNORMAL VOLTAGE> 4QOV PEAK

FULL WAVE
(RECTIFIED)

Figure 4.37 - Crowbar Circuit
SOLUTION: Check the MA series Harris Varistor specifications for a device capable of supporting 240V peak.
The V270MA4B can handle J 2 (171 V rms) = 242V. According to its specification of 270V ± 10%, the V270MA4B will
conduct 1mA de at no less than 243V. The gate-cathode resistor can be chosen to provide O.4V (the minimum trigger
voltage) at 1mA, and the SCR will not trigger below 243V. Therefore, RGK should be less than 400ft The highest value
5% tolerance resistor falling below 4000 is a 3600 resistor, which is selected. Thus, RGK is 3780 maximum and 3420
minimum. Minimum SCR trigger voltage ofO.4V requires a varistor ofO.4V /3780, or 1.06mA for a minimum varistor
voltage of = 245V. The maximum voltage to trigger the circuit is dependent upon the maximum current the varistor is
required to pass to trigger the SCR. For the C106 at 25°C, this is determined by calculating the maximum current
required to provide 0.8V across a parallel resistor comprised of the 3600 RGK selected and the equivalent gate-cathode
SCR resistor of 0.8V1200pA, since the C106 requires a maximum of 200pA trigger current. The SCR gate input
resistance is 4KO and the minimum equivalent gate-cathode resistance is the parallel combination of 4KO and RGK(min)'
or 3600 -5%, 3420. The parallel combination is 3250. Thus, Ivaristor for maximum voltage-to-trigger the CI06 is
0.8V/3150, or 2.54 mA. According to the specification sheet for the V270MA4B, the varistor will not exceed 330V with
this current. The circuit will, therefore, trigger at between 245 and 330V peak, and a 400V rated C106 can be used. The
reader is cautioned that SCR gate characteristics are sensitive to junction temperatures, and a value of25°C for the SCR
temperature was merely chosen as a convenient value for demonstrating design procedures.
Figure 4.3 can be used to determine the maximum energy per pulse with this waveform. It will not exceed
approximately 16/0. 15/Ip/Vp/ T (duration of 16 wave pulse), or 0.52mJ for this example. Since the voltage does not drop
to zero in this case, the SCR remains on, and the varistor sees only one pulse; thus, no steady-state power consideration
exists.

4.4.8 General Protection of Solid State Circuitry, Against Transients on 117V ac Lines
PROBLEM: Modern electronic equipment and home appliances contain solid state circuitry that is susceptible to
malfunction or damage caused by transient voltage spikes. The equipment is used in residential, commercial, and
industrial buildings. Some equipment designs are relatively low cost consumer items while others are for
commercial/industrial use where an added measure of reliability is needed. Since solid state circuits and the associated
transient sensitivity problem are relatively new, the knowledge of design in the transient environment is still incomplete.
Some test standards have been adopted by various agencies (see Chapter 7), and further definition of the environment is
underway by the Surge Protective Devices Committee of the IEEE.

4-25

The transients which may occur on residential and commercial ac lines are of many waveshapes and of varying severity
in terms of peak voltage, current, or energy. For suppressor application purposes, these may be reduced to three categories.
First, the most frequent transient might be the one represented by a 30 or 100kHz ring wave. This test surge is defined
by an oscillatory exponentially decaying voltage wave with a peak open circuit voltage of 6kV. This wave is considered
representative of transients observed and reported by studies in Europe and North America. These transients can be
caused by distant lightning strikes or distribution line switching. Due to the relatively high impedance and short duration
of these transients, peak current and surge energy are lower than the following categories.
The second category is that of surges produced by nearby lightning strokes. The severity of a lightning stroke is
characterized in terms of its peak current. The probability of a direct stroke of a given severity can be determined.
However, since the lightning current divides in many paths, the peak current available at an ac outlet within a building is
much less than the total current of the stroke. The standard impulse used to represent lightning and to test surge protective
devices is an S120ps current waveshape as defined by ANSI Standard C6S.2, and also described in ANSI/IEEE Standard
C62.41-19S0.
A third category of surges are those produced by the discharge of energy stored in inductive elements such as motors
and transformers. A test current of 1011 OOps waveshape is an accepted industry test impulse and can be considered
representative of these surges.
Although no hard-and-fast rules can be drawn as to the category and severity of surges which will occur, a helpful
guideline can be given to suggest varistors suitable in typical applications.
This guideline recognizes con~iderations such as equipment cost, equipment duty cycle, effect equipment downtime,
and balances the economics of equipment damage risk against surge protection cost.
Harris Varistor Selection Guideline for 117V AC Applications
Application Type

Duty Cycle

Location

Example

Suggested Model

Light Consumer
Consumer
Consumer
Light Industrial
Industrial
Industrial
Industrial

Very Low
Low
Medium
Medium
Medium
High
High

A
A
A

MixerIBlender
Portable TV
Console TV
Copier
Small Computer
Large Computer
Elevator Control

V130LA2
V130LAlOA
V130LA20A
V130LA20A or B
V130PA20A or C
V13lDA40 or DB40
V15lDA40 or DB40

B
B

B
B

REFERENCE
1. Kaufman, R., "The Magic of J2t" IEEE Trans. IGA-2, No.5, Sept.-Oct. 1966.

4-26

5
SUPPRESSION - TELECOMMUNICATIONS SYSTEMS
5.1 INTRODUCTION
Modern telecommunication systems are fast, efficient, and complex. Many improvements have been made in central
office equipment and subscriber equipment which involves the use of solid state circuitry. Unfortunately, solid state
devices are much more susceptible to malfunction or failure due to transient voltages and noise than are older devices,
such as relays, coils, step-switches, and vacuum tubes. To complicate matters further, increased usage of telecommuniation
lines for data and video transmissions has produced a further intolerance for transient voltages.
Although telecommunications systems have always employed transient protection devices such as the
carbon gap, the gas tube, and the heat coil, these are not always adequate to protect solid state circuitry.
Harris offers two distinct technologies to deal with the varied requirements of telecommunications transient
protection. The MOV, Metal Oxide Varistor, is a zinc oxide ceramic based technology, and the SURGECTOR, a
solid state silicon based process, which integrates a zener diode and the SCR technology on a single chip.
The requirements of the telecommunications industry are varied and unique. Both technologies have
adv,antages and limitations dependent on the specific application. The trade-offs are discussed in Section
5.14.

:i:

o

u(J)

5.2 SYSTEM TRANSIENTS
A telecommunication system is made up of subscriber stations linked together through the cable plant and a central
office switching network. Included in the system are repeater amplifiers, multiplexers, and other electronic circuits.
Supplying the electrical energy to run the system is a main power source.
The cable plant and the power supply provide a path by which damaging transients enter the system, to be transmitted
to vulnerable electronic circuitry. The cable plant consists of conductors in shielded cables, which are suspended on poles
(shared with power lines) or buried in the earth. A single cable is made up of many conductors, arranged in twisted pairs
(tip and ring). Some sections of open-wire transmission lines are still used, but most of these are remote from central
offices, and transient protectors are usually provided where the open wire enters the shielded cables. All of these cables
(even the ones underground) are capable of picking up transient energy from lightning and conducting them to the central
office or subscriber equipment.
The power used by a telecommunication system is usually obtained from commercial power lines. These lines, like the
telephone cables, are either suspended on poles or buried. Transient energy is frequently picked up by power lines and
transmitted to the central office by direct conduction or by induction into the telephone cable plant. The increased used of
off-line power supplies in telephone equipment makes power line transients even more hazardous to the electronic
circuitry.

5.3 LIGHTNING;;;;... INDUCED TRANSIENTS
Lightning is the most common source of over voltage in communication systems. Because of the exposure to lightning
strokes, a knowledge of the effects of lightning is important when designing a transient protective system.
Lightning currents may enter the conductive shield of a suspended cable by direct or indirect stroke, or it may enter a
cable buried in the ground by ground currents, as shown in Figure 5.l.
In the case of a suspended cable, the lightning current that enters the cable is seeking a ground and will travel in both
directions along the cable. Some of the current will leave the shield at each grounded pole along its path. Studies have
shown that all of the lightning current has left the cable shield after passing 10 poles grounded in high conductivity soils or
20 poles grounded in high resistivity soil.
5-1

~:i:
ww

1-1'(J)
~>
Do(J)
Do
:::I
(J)

--

SHIELD

Figure 5.1 - Lightning Current in Buried Cable

C;://////"////"//O
SHIELD

-----+ I

/ / '/ / / / / / // / / / / / /L,NSULAT,NG
JACKET

SHIELD VOLTAGE

UJ

'"..J
;0
o
>

SOIL VOLTAGE

IITRUE·GROUND

O~------~------------------------~~~~-----DISTANCE _ ...

Figure 5.2 - Condition for Puncture of Cable Jacket

Stroke currents leave a buried cable in a similar way but with a differe~t mechanism. Since the cable shield has a finite
electrical resistance, the current passing through it will produce a potential gradient along its length. This voltage will
produce a potential difference between the cable and the soil, as shown in Figure 5.2.
At some point (Point A) the shield-to-earth potential will exceed the dielectric strength of the jacket, causing it to
puncture. Some of the lightning current then flows through the puncture into the soil, thus equalizing the potential at that
point. The remaining current continues along the shield until another puncture occurs, providing another path to ground.
Lightning currents are usually not harmful to the shield itself, but they do induce surge voltages on the conductors of the
cable which ar~ often harmful to central office equipment. The surge voltage that appears at the ends of the cable depends
upon the distance to the disturbance, the type of cable, the shield material, and its thickness and insulation, as well as the
amplitude and waveshape of the lightning current in the shield. Since the current-derived potential along the cable shield is
capacitively coupled to the cabled conductors, the waveshape of the surge voltage on the eonductors will closely resemble
the waveshape of the lightning current.
Quantitative information on lightning has been accumulated from many sources,2 with research centers in the United
States, Western Europe and South Africa. One of the most comprehensive surveys of available data has been compiled by
Cianos and Pierce,3 describing the amplitude, rate-of-rise, duration, etc., in statistical terms.
Using these statistics, one can make numerical calculations of induced voltages in various electrical circuits, such as the
cable plant of a communication system. The parameters of interest are the voltages developed as a function of intensity
and duration of the lightning impulse. The examples discussed later in this chapter are based on this source of information.

5.4 CALCULATIONS OF CABLE TRANSIENTS
The voltage surge induced into the conductors of a cable will propagate as a traveling wave in both directions along the
cable from the region of induction. The cable acts as a transmission line. The surge current and voltage are related to each
other by Ohm's law where the ratio of voltage to current is the surge impedance (Zo) of the cable. Zo can also be expressed
in terms of the indUCtance (L) and capacitance (C) per unit length of the cable by the equation,
Zo =

vLle (0)

The velocity of the surge, as it propagates along the conductors, is also a function of Land e, and can be expressed as
Velocity = ,jULe (meters/sec.)
The series resistance of the shield and conductors, as well as losses due to corona and arcing, determine the energy lost as
the disturbance propagates along the cable.
5-2

Tests conducted on telephone cables4 have measured surge impedances of 800 between any of the conductors and the
shield. Shield resistances between 50 and 60 per mile were found to be typical. These values and the applied lightning
current waveform of Figure 5.3 were used to compute the worst case transient which would appear at cable terminals in a
central office.The computation assumes the lightning current is introduced into a suspended cable shield at a point 2.75
miles from the central office. An average cable span between poles of 165 feet, with a ground connection on every fourth
pole, was assumed. It was also assumed that the cable will support the voltage without arcing over.
100

'"~

~

80

w

~

"'-

"3

60

0<0

, 40

-........

~

fZ
W

~ 20
:J
U

o

a

50

25

----

75

100

TIME - MICROSECONDS

Figure 5.3 - Severe Lightning Current Waveform (2150J.ls)

355

'"~ 284

"'"'"

""I

213

/

.... 142

i5

'"

'"
:J

7I

/

<.>

o

o

10

/

I

"'"

IB.2

---.........

'J

J

g
g

11.0

~

7.3

'"~

3.7

~

0

'J

20

30

40

/\
V\

'" 14.7

50

o

/

~

/

10

20

30

40

-50

TIME - MICROSECONDS

TI ME - MICROSECONDS

Figure 5.5 - Open Circuit Voltage
2.75 Miles from lOOkA Lightning Stroke

Figure 5.4 - Available Current 2.75 Miles
from lOOkA Lightning Stroke

The resulting short-circuit current available at the central office is shown in Figure 5.4.
The open-circuit voltage at the cable end is shown in Figure 5.5. This analysis shows that if a severe, 100kA lightning
flash strikes a cable at a point 2.75 miles from a central office, a voltage transient reaching a peak of nearly 18kV may
appear at the cable end, with about 355A of current available.
Since the cable can be considered to be a linear system, the voltages and currents will bear a linear relation to the
lightning stroke amplitude. A tabulation of the open-circuit voltage and available current which would result from stroke
currents of various magnitudes is given in Table 5. Included in the table is the probability of occurrence, as given by Cianos
and Pierce. 3 It should be realized that voltages in excess of lOkV probably would not be sustained since the cable
insulation will break down.
The transient voltage at the central office in any case would be excessive, so that protectors would be required. The
protector would conduct up to 213A surge current for most (85%) of the strokes that occur and only up to twice that
current on rare occasions.

5-3

Table 5.1
Lightning Transients At Cable End 2.75 Miles from Stroke Point
Lightning Stroke,
Peak Current

Probability
of
Occurrence

Terminal
Open-Circuit
Voltage

(kA)

(%)

(Peak V)

Terminal
Short-Circuit
Current
(Peak A)

175
100
60
20

1
5
15
50

32,200
18,400
11,040
3,680

621
355
213
71

The values shown in Table 5.1 are based on the assumption of a single conductor cable with the stroke point 2.75 miles
from the central station. For closer strokes the peak short-circuit current at the cable end will increase as shown in Table
5.2. These calculations were made assuming a breakdown at the stroke point, which gives the worst case result.
Since telephone cables actually have many pairs of wires rather than a single conductor, the peak currents in each wire
will be lower. It is assumed that the stroke voltage will be induced equally in all wires if they are equally loaded. Then, the
currents in all wires will be equal if all protectors are identical. To predict the individual wire currents, it is assumed that
the wire currents are proportional to sheath curent and the ratio of resistances, and are reduced a constant amount by cable
inductance. Worst case calculated values for the shortest distances are shown in Table 5.2.
Table 5.2
Peak Lightning-Induced Currents in Various Lengths
of Telephone Cable (100kA Lightning Stroke)
Distance
To Stroke
(Miles)
2.75
1.50
1.00
0.50
0.25

At
Stroke
Point
630
630
734
1110
1480

Peak Currents (A)
At Central Office
Single
6 Pair
Conductor
Cable
355
637
799
1120
712
1480
852

12 Pair
Cable
-

453
463

An example of the current which a protective device must handle can now be estimated. Assume a cable of six pairs (the
smallest available) is struck by lightning, inducing a stroke current of 100kA into the shield, at a distance of 0.25 mile from
the protector. The transient current will be divided up among the twelve suppressors at the cable ends. Each protective
device must handle up to 852A of peak current in order to clamp the voltage to a protected level.

5.5 POWER SYSTEM-INDUCED TRANSIENTS
Since telephone cables very often share a pole and ground wire with the commercial ac utility power system, the high
currents that accompany power system faults can induce over-voltages in the telephone cables. These induced overvoltages will be at the power system frequency and can have long duration (compared to the lightning-induced transients)
from a few milliseconds to several cycles of power frequency. Three types of over-voltage can occur in conjunction with
power system faults:
Power Contact

(Sometimes called "power cross") The power lines fall and make contact with the
telephone cable.

Power Induction

The electromagnetic coupling between the power system experiencing a heavy fault
and the telephone cable produces an over-voltage in the cable.

Ground Potential Rise

The heavy ground currents of power system faults flow in the common ground
connections and cause substantial differences in potential.

5-4

There is little definitive data available on the severity of these over-voltages. However, proposals have been made by
telephone protection engineers to define the power contact as the most severe condition. The proposed requirement calls
for the suppressor to withstand lOA RMS for a duration of power contact ranging from 10 to 60 cycles of the power
system frequency.

5.6 PROTECTORS - VOLTAGE TRANSIENT SUPPRESSORS
5.6.1 Primary Protection
The oldest and most commonly used primary protector for a telephone system is the carbon block spark gap. The
device is made up of two carbon block electrodes separated by a small air gap of between 0.003 and 0.004 inch. One
electrode is connected to the telephone cable conductor and the other to the system ground. When an over-voltage
transient appears, the gap breaks down diverting the transient and dissipating the energy in the arc and the source
impedance of the transient. The carbon gap is a low-cost protector but suffers from a relatively short life and exhibits
sparkover voltage variations. Nominal 3-mil carbon gaps statistically sparkover as low as 300V and as high as 1000V
-this is a serious problem.
Telephone conductors occur in pairs in a cable so that transient voltages induced into the conductors will be common to
both tip and ring conductors, as shown in Figure 5.6. This longitudinal voltage produces no current through the load
termination. Normally, there is zero difference in the potential between conductors. If protector, PRJ should break down
at 400V, while PR2 requires 700V to break down, then only PRJ would breakdown on transient of 600V causing a
transient current flow through the load. Even if PR2 does break down but responds later in time than PRJ a transient
current will flow.

INDUCED
LONGITUDINAL VOLTAGE
IN CONDUCTOR PAIR

EQUIPMENT
TERMINATION

Figure 5.6 - Unbalanced Line Protection
Another common suppressor in telephone systems is the gas tube protector. It consists of two metallic gaps spaced by a
distance of 0.0 10 to 0.015 inch. The electrodes are enclosed in a sealed glass envelope containing a combination of gases at
a low pressure. Such gaps offer higher current-carrying capability and longer life than do carbon block devices. However,
the possibility of seal leakage and the consequent loss of protection has limited the use of these devices. Dual-gap gas tubes,
also called three-electrode gas tubes, have been introduced to alleviate the problem of unbalanced breakdown as
described in the preceding paragraph.
Harris Varistors have properties that make them excellent candidates for telephone system protectors.
These characteristics include tight tolerance, high reliability, high energy capability, and good clamping characteristics.
The V130LA20A Harris Varistor, for instance, is capable of handling a peak transient current of6500A (S/20ps
pulse) and dissipating up to 70J of energy. The 6500A current surge would result in the voltage across the
varistor being clamped at a maximum of 600V. A 1000A pulse would be clamped to less than 420V, yet ring
voltage peaks of lS0V would not be affected by this varistor.

5-5

Varistors are often used in telecommunication circuits between tip, ring and ground requiring 1,2 or sometimes 3
separate varistors. See Figure 5.7.

TIP

RESISTOR OR
FUSE OPTIONAL

RESISTOR
OR FUSE

TIP

RING

TIP

RING

RING
RESISTOR
OR FUSE

Figure 5.7 - Varistor Connection Between Tip and Ring
The voltage rating of the varistor is determined by the voltage applied between tip and ring. Most telecommunication
systems have 52.5V dc with a superimposed ring voltage between 40 to 150V RMS (21OV peak), which results in a
minimum voltage rating for the varistor of 52.5V + 210V = 262.5V. The proper device would have a minimum
DC-voltage rating of greater than 262.5V. For example, a V230LA20A, two V130LAlOA devices in series, or two
V130LA20A devices in series would be appropriate.

5.6.2 Secondary Protection
Modern solid state communications circuitry can be damaged even if the primary protection is working normally. It is
often advisable to provide a secondary protection system to further reduce the voltage transient. As shown in Figure 5.8,
the secondary protection removes the over-voltage spike which is passed by the primary protector.

~

T!ME OF
I rRESPONSE
PRIMARY PROTECTION

ZLI

~ZL2

~

----+----~NY-r~--~-----+~~--+_~~-~------.~6~~~~
HARRIS VARISTOR
SECONDARY
PROTECTOR

Figure 5.8 -

Secondary Protection

In most installations the length of conductor between the primary protector and the telephone circuit boards is greater
than 25 feet. The impedance (Zd presented by this length of wire to most lightning-induced transient voltages will insure
that the primary protector will operate first and the secondary protector will not be exposed to the full surge. In the rare
cases where a power cross occurs, the varistor may fail, but it will still perform its assigned task of protecting the circuit
board. Because its failure mode is a short circuit it will blow the system fuses. Usually the probability of a power cross if so
low that the replacement of a damaged varistor is an acceptable alternative to repairing a damaged circuit board.
The SURGECTOR can also be a desirable transient protector for secondary protection. Its "crowbar" action
and fast response time can shunt the transient to ground effectively and prevent damage to the system. The
characteristics and forms of SURGECTORS are discussed in Section 5.9 and 10.1.

5-6

5.7 POWER LINE TRANSIENTS
Fortransients introduced into a telecommunications system through the powerlines, the Harris Varistor is a
very effective suppressor. Properly selected, the varistor will not effect the normal operation of the line but will
clamp heavy transient surges to an acceptable voltage level. Refer to Chapters 2, 4 and 9 for information on the
selection of a varistor suppressor.

5.8 RELAY CONTACT PROTECTION
Even the most modern telephone equipment requires the use of relays and other electromechanical switching devices.
These device are required to switch currents into inductive loads causing contact arcing, pitting, and noise generation. The
Harris Varistor is a useful suppressor for increasing contact life, improving reliability, and reducing noise.
Chapters 1 and 4 contain selection information for contact protection applications by means of varistors.

5.9 SURGECTOR'" TRANSIENT SURGE SUPPRESSOR
The Harris SURGECTOR is a new type of surge-suppressor, developed to protect sophisticated electronic
circuits from rapid, high-voltage power surges that conventional surge suppressors cannot handle. The need
for a new type of surge suppressor stems from the increasing sophistication of today's electronics. In the
telecommunications industry, for example, the trend is toward increasing use of medium-scale integrated
(MSI) and very large-scale integrated (VLSI) circuits. These circuits are used in equipment that transmits,
processes, codes, switches, stores data, and has multifunction capability, but is intolerant of voltage overloads.
In addition, a strong shunt device, such as the SURGECTOR, is used to open a series device, such as a fuse, to
prevent excessive current overloads of premise wiring and equipment as required by safety agencies (e.g.,
Underwriters Laboratories).
The SURGECTOR is a monolithic device. It consists of an SCR-type thyristor whose gate region contains a
special diffused section that acts as a zener (avalanche) diode. The zener portion of the SURGECTOR
provides continuous protection of the circuit.
Because it combines the continuous voltage protection of the zener with the thyristor'S ability to handle high
current, the SURGECTOR provides instantaneous protection against fast-rising, high-voltage pulses- pulses that
are too rapid or too powerful for conventional devices (such as gas tubes, air-gap carbon blocks, or stand-alone
zeners) to block. As a result, the SURGECTOR can provide the much-needed secondary surge protection for telecommunications circuitry, data links, and other sensitive electronic circuits that are especially susceptible to damage from transient voltage.
Surge Characteristics
•
•
•
•

CAf.T:~DE K

Large voltage and energy variations
Wide variations in surge durations
Possible rapid repetition and mixed polarity ot surges
dv/dt ot up to
Vlp.s

:

SHUNT

,aooo

ZENER
p+

SURGECTOR Characteristics
High input impedance until breakdown (i. e. low leakage)
Repeatable breakdown/threshold voltage
High surge current handling capability
Withstand and respond to rapidly reoccurring surges
• Fast recovery to high impedance state (turn-ott)
• Dual polarity protection
• No degradation ot essential characteristics with use

•
•
•
•

ANODE
CATHODE
OXIDE

EPI WAFER

p.

n+

ANODe

ZENER

Figure 5.9 - SURGECTOR Vertical Structure
REPEATERS

TIP
RING

~

CENTRAL
OFFICE

CENTRAL
OFFICE

DECODE
CONTROL

DECODE
CONTROL

PABX

PABX

SWITCH
NETWORK

SWITCH
NETWORK

SURGECTORs Provide Transient
Protection for:
TIP
RING

5-7

• Central Office Equipment
• Supervisory Equipment
• SwItchgear Equipment
• Data Transmission
• Handsets
• EPABX, PABX, PBX

• Repeaters
• Line Concentrator
• Receivers
• Headsets
• Modem
• PCM

5.10 SURGECTOR OPERATION
The SURGECTOR allows normal operation of the circuit as long as the voltage does not exceed a certain maximum value (VDM). Current SURGECTOR devices are rated at 30,60,100,230, and 270 volts. When a transient
pulse hits the line, voltage begins to rise - often as an extremely rapid rate. Lightning, for example, can cause a
voltage rise in excess of 1000 volts per microsecond. As soon as the voltage reaches the avalanche breakdown
voltage, the zener instantly "clamps the voltage. The voltage can rise above its normal value for the circuit, but
only by a small amount; the SURGECTOR ensures that the protected circuit never sees a voltage greater than 110
percent of the zener avalanche operating voltage.
A normal stand alone zener diode maintains a constant voltage for the duration of the pulse and can quickly
burn out from this energy overload. But in the SURGECTOR, current flows from the zener region into the thyristor gate, switching on the thyristor in nanoseconds. The thyristor drops to low voltage, creating a low impedance
in the circuit, and shunts the excess energy from the circuit to the ground. In effect, the thyristor draws energy
away from the zener, allowing it to survive the transient. Because of this, the SURGECTOR can handle about ten
times more current than a stand alone zener.
While the transient is on the line, the SURGECTOR remains in the ON state, and the voltage across the circuit
is low. Its precise value depends on the type of pulse and the type of SURGECTOR being used. Eventually, the
pulse passes, and the current begins to drop. When it reaches a certain minimum value, known as the "holding
current," the SURGECTOR automatically shuts off, and normal circuit operation resumes, with the zener section
of the SURGECTOR again providing continuous protection.

200
1.5K VI ~s INDUSTRY STANDARD
lIGHTNING STROKE

150
250

•



r

0
20

~

500
400

'" i'----

175

~
'-.......

o

260

"~

240

'-.......

150

'-.......

o
I
20

125

LL~~~~:=========
2.0

10.0

1000

10040
-

TIME (Ils)

Figure 5.12 - SURGECTOR Devices Clip Voltage
Surges and Shunt Energy to Ground

-30 - 20 -10

0

10

20

3D

40

50

60

I'-- i'-

70

80

90

AMBIENT TEMPERATURE (TA1-degC

Figure 5.13 - Typical Holding Current vs. Temperature

5-9

~

o
o

III

~~

WW

1-1• III

i.Z>

c...lIl
c...

;:)

III

SURGECTOR devices are usually used in conjunction with primary protection devices, and therefore should rarely see
currents exceeding their rated capacities. When operated within their specifications, SURGECTOR devices automatically
swi~h to their off-state once the pulse passes and the current drops below the holding current. The holding current of the
SURGECTOR must be greater than the normally available short-circuit current in the circuit to insure that the SURGECTOR will return to the off-state when the transient has passed and allow normal circuit operation to resume. SURGECTOR
devices are designed with high holding currents, ranging from 100 to 270 milliamps, depending on the type. These ratings
are sufficient to allow proper operation in most telecommunications circuits.
The SURGECTOR device's normal off condition is a state of high impedance, which prevents loading of the line. Leakage is extremely low; the SURGECTOR passes less than 100 nanoamps. The capacitance of SURGECTOR devices is also
low, presenting about 100 pF for a bidirectional device in normal telecommunication circuits. This is low enough to allow
high-speed data communications.

5.13 NOMENCLATURE, PACKAGES, AND SHIPPING
The SURGECTOR type numbers are easy to interpret. The first three characters - the letter "SGT' - stand for SURGECTOR. Next comes two digits, which represent the maximum off-state voltage divided by 10. Following the voltage is a letter
indicating either SCR (S), Unidirectional (U), or Bidirectional (B). The next two digits indicate holding current in milliamps
divided by 10.

All versions of the SURGECTOR are housed in a modified TO-202 versatab plastic package. This is a
single-in-line package, meaning that all leads come out of the same end and are parallel to one another. The
advantage of single-in-line packaging is that it makes the SURGECTOR easy to insert into a circuit board or
socket by automated methods.
SURGECTOR devices are shipped to the customer either in bulk or on plastic "sticks" designed for
automated machinery handling. The sticks are rectangular tubes that hold 50 SURGECTOR devices each.

Nomenclature For SCR, Unidirectional and Bidirectional

Holding currenl In milliamps divided by 10
Type.of SURGECTOR:
U = Unidirectional
B = Bidirectional
S = SCR
Olf-Stale Voltage Rating divided by 10
SURGECTOR

SURGECTOR Packages

Modified TO-202
Package Style
Package A

Package B

SURGECTOR devices are shipped to the customer either in bulk
or on plastic "sticks" deSigned for automated machinery handling.
The sticks are rectangular tubes that hold 50 SURGECTOR
devices each.

Figure 5.14- Plastic Shipping Thbes

5-10

TYPE NO.

FUNCTION

SGTlOS10t
SGT27S10t
SGT27S23t

VARCLAMP
VARCLAMP
VARCLAMP

SGT03U13
SGT06Ul3
SGT23Ul3

UNI-DIRECT
UNI-DIRECT
UNI-DIRECT
BI-DIRECT
BI-DIRECT
BI-DIRECT
BI-DIRECT
BI-DIRECT
BI-DIRECT

SG1'23B13
SGT27BI3
SGT23B32'
SG1'27B32'
SG1'23B27
SGT27B27

t Dependent on trigger circuit.

V2 MIN
V

VBOMAX
(IOOV/flO)

ITSM
(lx2f1S)

ITSM
(lOx 1000fl8)

mAl

PACKAGE
STYLE

100
270
270
30
60
230
230
270
230
270
230
270

t
t
t
<50
< 85
<275
<285
<345
<290
<350
<290
<350

300
300
300
300
300
300
300
300
300
300
600
600

100
100
100
100
100
100
100
100
100
100
200
200

> 100
> 100
>230
> 130
> 130
> 130
> 130
> 130
>320
>320
>270
>270

A
A
A
B
B
B
B
B
B
B
B
B

• Preliminary Data Sheets.

IH

All finalized devices UL recognized to 497B - File Number E135010.

5.14 APPLICATIONS
Telecommunications equipment has to operate in extreme transient/surge environments. Transients may
originate from power mains, switching sources, lightning and electrostatic discharges. Isolation, grounding,
and shielding among others, are methods used to control transients but while these techniques may be used
in various telecom applications they are not totally effective.
The Harris line of SURGECTOR devices protects circuits from damage better than Transorb ® zeners, gas-discharge
tubes, spark-gaps and any other means of protection. SURGECTOR devices offer continuous protection with unique ability
to clamp at specific voltages (30Y, 60V, lOOY, 230Y or 270Y) which then trigger the SCR on and bypass the energy away
from the circuit. The Harris SURGECTOR may be used in many applications to provide transient energy protection at subscriber stations and central offices where other suppression devices do not provide adequate protection for newer more sensitive circuit components. The SURGECTOR combines the protection of crowbar-acting devices and fast voltage-clamping
!devices. They combine the clamping voltage temperature coefficient and low clamping-voltage ratio of a zener diode with
the high current surge capability of a spark gap (gas-discharge tube) device. Bidirectional devices provide this protection in
either polarity as in the case of the gas-discharge tube.

TIP

TIP
SURGECTOR

TELEPHONE

LINE PAIR

INCOMING
LINE

TO
PROTECTED
eQUIPMENT

SURGECTOR

RING

RING

Figure 5.15 - Full balanced protection employing
three unidirectional SURGECTOR
devices and three diodes.

Figure 5.16· Two bidirectional SURGECTOR devices
are placed between the tip and ring lines
just after these lines enter the telephone
to protect delicate telecommunications.

5-11

GNO
LINE

v..,

INTEGRATED

sLie

v..,
- 48V
LINE

Figure 5.17 - Full balanced protection using three terminal SURGECTOR devices.

Typical Transient Surge Suppressor Applications
Transient
Surge
Suppression
Devices

Data Lines

Telecom
(Primary)

Telecom
(Secondary)

.;
.;

.;
.;

.;
.;
.;

SURGECTOR
MOV
AVALANCHE
DIODE

.;

AC Power
Lines

DC Power &
Automotive

.;

.;
.;
.;

.;

GAS TUBE

Comparison of Surge Suppression Devices
Transient
Surge
Suppression
Devices

SURGECTOR

Major Limitations

Major Advantages/Uses

+ Ideal for datacom and telecom
+ Leakage - 20,000 Amps
+ Leakage - subpicoamps
+ Shunt capacitance - <1 pF
+ Lifetime @ sao Amps, 8x20 flS pulse width 200 surges

5-12

- Shunt capacitance - >SOO pF
- Leakage - approximately 10 microamps
- Clamp voltage goes up with current

- Low-surge capability - SO Amps @ 8x20 flS
pulse shape
- Leakage - approximately 10 microamps
- Clamp voltage goes up with current

-

Response time -  100 (rnA)

1

PROPOSED END-POINT QUALIFICATION
------------------------

CLAMPING VOLTAGE CHANGE (% AT 20A)
rnA

N=8

(%J 0

SUPPRESSOR

LOAD
DUMP

~

+5

1~

~======:::::====::=:===::=:;
1 DUMP
10 DUMPS
JUMP
AT 100J

AT ZOO J

0.1

0.01

START

24V

0.001 '--________-1-__________--1-_________
10 DUMPS
AT 100J

-5

1 DUMP
AT 200 J

JUMP
START

24V

Figure 6.S - Stability of Oampiog Voltage

Figure 6.6 - Stability of Standby Current

6-4

6.2.2 Protection of Electronic Ignition
In the second example, the protection of the output power transistor in an electronic ignition circuit is analyzed. This
power transistor performs the current switching function of mechanical distributor points in the usual Kettering ignition,
thus avoiding the pitting, burning, and erosion mechanisms associated with the mechanical points. The ignition circuit is
illustrated in Figure 6.7.

v.o---------.--,
SYSTEM CONDITIONS

TIMING
SIGNAL

CONDITION

v.

START
SWITCH

RUNNING

12V TO 16V

OPEN

STARTING

5V TO 12V

CLOSED

OPERATING TEMPERATURE RANGE
-40·C TO +IIO·C

JL
POWER
TRANSISTOR

Figure 6.7 -

Typical Electronic Ignition Circuit

In normal operation, the coil primary current builds up when the power transistor is on, storing energy in the coil
inductance. The power transistor is then switched off, and the voltage at the collector rises rapidly as the capacitor, C,
charges. Transformer action causes the secondary voltage to rise until the spark plug reaches firing voltage, clamping the
transistor collector voltage at a safe value. If a spark plug is fouled or disconnected, the collector voltage can rise until
either the capacitor contains the stored energy (minus losses), or the transistor breaks down with resulting damage/failure.
Since the capacitor is small, transfer of the stored energy of the coil to the capacitor would result in a very high voltage
requiring transistor protection. A varistor can be used to turn the transistor on during the period of high voltage, thus
dissipating the excess energy safely as heat. The constraints on varistor selection are: clamp voltage must be low enough to
protect the transistor; clamp voltage must be high enough to not affect normal spark energy; the power dissipation (with
two spark plugs disconnected) must be within varistor ratings for an 8-cylinder, 4-cycle engine at 3300 rpm (misfires at
55Hz, average). The minimum spark voltage output required is 20,000V, which represents 200V at the transistor
collector. The transistor has a breakdown voltage rating of 400V with the 470 base emitter resistor and a current gain over
20. The base emitter on-state voltage, VBE(ON)' is between 1.0 and 1.8V, and the collector to emitter saturation voltage is
between 0.9 and 1.5V. The varistor clamp voltage range is determined by the 200V needed to supply minimum spark
voltage and the 400V rating of the transistor. At 200V the varistor current must be less than:
VBE(ON/ 470 =

IV
470

= 0.02A

to prevent unwanted transistor turn-on. The minimum varistor voltage at the 1rnA varistor specification point is found by
solving the varistor voltage equation:
1= kVa,

assuming a maximum a of 40. The result is l86V. The peak clamping current (at 400V- VBE(MAX» is found from the
energy balance equation for the coil, using the peak coil current, Ic. Ic maximum is analyzed under both start and run
conditions to determine the worst case:
:s:::: 12 - 0.9 =
6.l7A
IC(,tart)
""'" 1.80
and,
:s:::: 16 - 0.9 =
4.2A
ICCrun) ""'" 3.60

6-5

o
t-I!?

~z
.!:!:!
zOO

- z
8:~
~t-

The worst case coil current occurs with the start switch closed and will be less than 6.2A. The maximum peak coil current,
Ip' when clamping is then:
and with a Vp of 4OOV:
Ip2 = Ic2 - 4002 CIL
results in 6.0A starting and 3.6A running. The varistor currents corresponding to this are:
I/hFE

+ VBE/470;

which gives 0.34A starting and 0.22A running. Peak varistor voltage must be less than:
400V - VBE (i.e., 398V at 0.34A)
The varistor power dissipation at 3300 rpm (55pps), assuming a triangUlar current waveform with constant voltage and
no losses, is found from coil energy balance:

solving for t:
t

= (7)(10.3) H (3.6A)
400V

63f1S

The varistor power dissipation is found to be:
VMAX

TI

tf= 398V (0.22A)
- 2 - (63)(lo-6)S(55pps)=O.l5W

Observations indicate that the losses in the coil and reflected secondary load will reduce this by half to about 75m W.
Using the 110 0 C ambient temperature derating factor of 0.53, it is found that a varistor ofO.15W dissipation capability is
required. The varistor parameters are now defined as Vx of at least 186V at I mA but less than 398V at 0.34A and capable
of at least 0.15W dissipation. The V220MA2A and V270MA4B both fit these requirements.
As these examples have illustrated, the use of the Harris Varistor in automotive circuits for transient
protection is both technically and economically sound. Design procedures are identical to the procedures used
in the other environments. Experimental verification of the degree of protection can be made using standard
waveforms reported by automotive engineering investigators.

REFERENCES
I. Preliminary Recommended Environmental Practices for Electronic Equipment Design, Society of Automotive
Engineers, 2 Pennsylvania Plaza, N.Y., N.Y. 10001.
2. Electromagnetic Susceptibility Test Procedures for Vehicle Components (except Aircraft), Society of Automotive
Engineers, 2 Pennsylvania Plaza, N.Y., N.Y. 10001.
3. Korn, S.R., "Transient Voltage Suppression in Automotive Vehicles," SS-8766.

6-6

--

7
VARISTOR TESTING
7.1 INTRODUCTION
As with any device, metal-oxide varistors possess a number of parameters which can be identified and measured in
several ways. However, to minimize testing effort, the test parameters should be reduced to the essential few. Also, tests
should be conducted in a standard way to assure correlation of measured values between maker and user. The essential
varistor parameters are defined in Chapter 3. This chapter will detail the tests of these varistor parameters, describe
suitable test methods using simplified test circuits, and list some available test equipment.
It should be noted that all tests are performed at 25 0 C, unless otherwise specified. Also, the test circuits and methods
given herein are intended as a general guide only, and may not be generally applicable to the test equipment available to
the user. Since the tests frequently entail high voltages and currents, the user must exercise appropriate safety precautions.

7.2 TEST OBJECTIVES
Varistor testing that would be undertaken by a user will depend considerably on prior knowledge of both the device
and the application. Factors are the relative severity of the application (both electrical and environmental), the number of
devices to be used, and the possible adverse effect of device misapplication or malfunction. Further considerations are
resources available to the user and the economics of alternate uses of those resources versus more extensive varistor testing.
Equipment makers designing transient protection into their products will have different objectives in varistor testing than
a user simply adding a few varistors to existing equipment as a protective step. Finally, the user may have different test
requirements depending on which point in the cycle of system design or component evaluation and procurement the
testing is being done.

7.2.1 Engineering Evaluation
For the original equipment maker, the process of evaluating and procuring a new component begins with an initial
evaluation of the component itself. Typically, the circuit or systems engineer will obtain a few samples of the candidate
component for evaluation in the prototype equipment design. He may seek recommendations from his component
engineer in selecting from devices available in the market. It is important to focus on the key characteristics and ratings to
determine if the component can perform as expected. Typically, varistor voltage, clamping voltage, standby current,
insulation resistance, and capacitance of the samples should be measured according to the methods given in Section 7.3.
Assuming that a varistor type has been selectfd according to the design application examples of Chapter 4, the engineer
obviously will verify that the component performs as expected when placed in the breadboard circuit. Also, it should be
verified that variation of these parameters within their specification values are consistent with the application
requirements. The surge current, or energy, and waveshape available in the circuit together with its frequency of
occurrence should be measured or computed. These characteristics of the expected transients should then be checked
against the pulse lifetime and the power dissipation ratings of the selected varistor type. Where suitable equipment is
available, the rating of the varistor may be verified by injections of transients into the varistor alone or into the prototype
circuit. See Section 7.6 and 7.7 of this chapter for a discussion of transient test equipment and test waves.

7.2.2 Product Qualification
In some user organizations, selection and evaluation of the varistor as a component may pass to a specialized group that
evaluates component engineering and reliability. The final output of this evaluation will be a purchase specification
detailing the mechanical and electrical requirements and ratings of the component, and possible approved sources for the
part. A product qualification plan often will be used to detail the electrical and environmental tests to which a sample of
the candidate component may be subjected and which it must pass in order to be approved. Frequently the manufacturer

7-1

will be asked to supply supporting data for his in-house testing to supplement and minimize the qualification testing. The
suggested electrical characteristics tests are (with appropriate conditions and limits): nominal varistor voltage,VN;
maximum clamping voltage, Vc; dc standby current, ID (optional, especially for ac applications); insulation resistance; and
capacitance. These characteristics will be measured frequently in the componentlequipment cycle thereafter, and care
should be exercised that they are neither too many and complex nor too few tb be meaningful to the application.
Reliability requirements of operating conditions and expected life will sometimes be specified and usually tested for early
in the qualification phase of the component. These tests may be performed at special conditions of environment or
temperature to stress the component as proof of its intended use or design capability. A test to insure surge current
withstand capability may be included in the qualification plan. This test must be carefully performed and specified (by
using either 8120,us or lO/lOOO,us waveshapes) in line with the recommendations of Chapter 3 and consistent with the
pulse lifetime rating chart of the varistor selected. Other qualification tests may be used to ensure mechanical integrity,
humidity resistance, solderability, and terminal/lead strength. These tests should be of a standard nature wherever
possible to assure reproducibility.

7.2.3 Incoming Inspection
Once the component has been qualified, the equipment maker will wish to verify that shipments received consist of
correct parts at the expected quality level. Shipments will be sample-tested to assure correct markings, appearance, finish,
and major or critical electrical parameters. It is especially desirable to prevent material with incorrect voltage
characteristics from entering assembly operations so as to minimize troubleshooting and rework. For incoming inspection
of Harris Varistors,it is recommended that sample testing include nominal varistor voltage, VN, tested against the
minimum and maximum voltages specified on the purchase drawing/specification. Components below specification
limits may lead to premature degradation or circuit failure. If above specification, they may not deliver the required
protection from transients and may possibly allow other failures. Other electrical sampling tests frequently performed can
include insulation resistance and capacitance. Tests such as maximum clamping voltage, Vo and dc standby current, ID,
are usually checked only on a periodic audit basis.

7.2.4 Field Maintenance
Field maintenance testing is done to verify that the varistor is still providing the intended protection
function or, in the case of sensitive circuit applications, that the varistor has not degraded. Since the usual
change of Harris Varistor characteristics when over-stressed is toward lower resistance, it is very unlikely that
the protection function will deteriorate unless the electrode system is damaged. The varistor should be
physically examined for loose leads, charred or broken areas in the encapsulant, solder dribbles on the leads,
or other evidence of overheating damage. If physically acceptable, the varistor may be tested electrically.
The nominal varistor voltage should be tested against the minimum limits for the model using the method described in
Section 7.3.1. If the varistor is open, short, or more than 10% outside either limit, it should be discarded. The dc standby
current also should be measured. If more than twice the specification, the varistor is significantly degraded and should be
discarded. If the varistor is physically sound and shows no evidence of degradation in these electrical tests, it is fully
functional.

7.3 MEASUREMENT OF VARISTOR CHARACTERISTICS'
7.3.1 Nominal Varistor Voltage VN
This is measured at a dc test current, IN' of ImA for product models. A simplified circuit for instrumenting this test,
shown in Figure 7.1, is suitable for varistors up through a rating of 300V RMS. Above the 300V RMS rating, a higher
supply voltage will be needed. Resistor Rl has a dual purpose. In conjunction with the variable voltage supply, El, it
forms a quasi-current source providing up to 6mA when switch Sl is closed. Also, Rl is used as a current sensor to
measure current flowing through the varistor-under-test. To use the circuit, the operator places switch S2 in position I and
S3 into position VN' A test device is then inserted into the socket and SI is closed. El is then adjusted to obtain a reading of
100 ±5V on the digital voltmeter. Approximately ImA of current will be flowing in Rl. When switch S2 is placed in
position V, the varistor voltage will be indicated on the voltmeter. The values ofRI and El supply voltage can be scaled
appropriately for other voltage-current test points.

7-2

S10

~ 'e---Rl-~P------'
0- 600-"'.L
El
DVM

R1=100kn,1 %,lW(VN TEST)

R2=lkrl..l%,1I2W(I D TEST)

Figure 7.1 - Simplified Circuit for Varistor Voltage and DC Standby Current Tests

If the varistor voltage test is implemented on automatic test equipment, a "soak" time of 20ms minimum should be
allowed after application of test current before voltage measurement. This is necessary to allow varistor voltage to settle
toward a steady-state value. Figure 7.2 illustrates the time response of a specimen varistor with a constant 1.OmA current
applied. As can be seen, the varistor voltage initially may rise to a value up to 6% greater than final. With a 20ms or greater
soak time, the measured value will differ by less than 2% from the steady-state value.
For varistor models that are commonly used on 60Hz power lines, the VN limits may be specified for a I.OmA peak ac
current applied. If an ac test is preferred by the user, a schematic approach similar to that shown in Figure 7.1 is used,
except an ac Variac'M is substituted for the dc power supply, and an oscilloscope is substituted for the voltmeter. This
circuit is equivalent to that of a typical curve tracer instrument.

v (t)
5V1DIV

240V

-- - - 1,·1
--

250V

.~

~~

I ~

• •

i_

~

i

I

230V

II

I

n

I

I,
II

-

i

I ms/DIV
Oms/DIV
IOOms/DIV
I,OOOms/DIV

Figure 7.2 - Voltage-Time V(T) Characteristics ofa Harris Varistor (V130LAIOA)

Operating at a Constant DC Current of 1.0mA

To avoid unnecessary concern over minor measurement anomalies, three behavioral phenomena of metal-oxide
varistors should be noted. First, it is normal for the peak varistor voltage measured with ac current to be about 2% to 5%
higher than the dc value, as illustrated by Figure 7.3. This "ac-dc difference" is to be expected, since the one-quarter cycle
period of a 60Hz wave is much less than the 20ms minimum settling time required for dc readout.

7-3

0:"

Oz

1-(/)1-(/)
O:w

~I-

,he'"~IOO

- Itc6J

o

>

,

I

w

~

I

~

I
10

~,

-

~.

130 V RMS RATED
PRODUCTMEDIUM-VOLTAGE

/

./ -

~.

CURRENT - I

rERIAr-

-

~4

-

~.

-

~I

-

~I

AMPERES

Figure 7.3 - AC and DC Characteristic Curves

Second, it is normal for the varistor voltage to increase slightly when first subjected to electrical current, as shown in
Figure 7.4. This might be considered a "break-in" stabilization ofthe varistor characteristics. During normal measurement
the voltage shift typically is less than 1%. This voltage shift is of little consequence for most measurement purposes but
might be noticeable when viewing a DVM as in the test method of Figure 7.1. The visual DVM observation should be
made shortly after power is applied, with measurement to not more than three significant figures.
v(t)

5V/DIV

- - -.... t.50mS/DIV

Figure 7.4 - (V130LAlOA) Varistor Voltage for the Initial Cycles of 60Hz
Operation at a Peak Current of 1.0mA

Third, it is normal for the varistor voltage-current characteristic to become slightly asymmetrical in polarity under
application of dc electrical stress over time. The varistor voltage will increase in the same direction as the polarity of stress,
while it will be constant or will decrease in the opposite polarity. This effect will be most noticeable for a varistor that has
been subjected to unipolar pulse stresses or accelerated dc life tests. Therefore, to obtain consistent results during unipolar
pulse or operating life tests, it is essential to provide a polarity identification for the test specimens. However, for initial
readout purposes, this effect usually is insignificant.

7-4

7.3.2 Maximum Clamping Voltage, Vc
As discussed in Chapter 3, the clamping voltage of a varistor is best defined in terms of the current impulse impressed on
the varistor, rather than in terms of applied voltage. Two typical current impulses that may be used to define the varistor
clamping voltage are the 8120t's and the 1OIlOOOt's pulses. Figure 7.S shows typical varistor test waveforms for these
two impulses.
The clamping voltage of a given model varistor at a defined current is related by a factor of the varistor voltage.
Therefore, a test of the nominal varistor voltage against specifications may be sufficient to provide reasonable assurance
that the maximum clamping voltage specification is also satisfied. When it is necessary to perform the Vc test, special surge
generators are required. For shorter impulses than 8120t's, precautions must be observed to avoid an erroneous
"overshoot" in the measurement of the clamping voltage. Section 7.6 gives general information on surge generators; a
brief description of the "overshoot" effect follows.

500mV

.,.

500mV

lOps

U
~

100V/div.
'-y

I

....

~,

~

I~~

Il'

1Il~ :0IIII
l

~

~,

l'

o

I

1ms

•

..

10A/div.

100mV

1V

~

~...

-

~~

::

::-=
10,u.s /div.

=

lms Idiv.

bll0 11000JLs wave Ip ::;: SOA. Vc::;: 315V

a) 81 20ILs wave I" = 50A, VI' = 315V

Figure 7.5 - Typical Oamping Voltage Test Waveforms (Harris Varistor Type V130LAIOA)
The Harris Varistor specification sheets show the V-I characteristic of the devices on the basis of maximum
voltage appearing across the device during a current pulse of 8120t's. If current impulses of equal magnitude but faster rise
are applied to the varistor, higher voltages will appear across the device. These higher voltages, described as "overshoot,"
are partially the result of an intrinsic increase in the varistor voltage, but mostly of the inductive effect of the unavoidable
lead length. Therefore, as some applications may require current impulses of shorter rise time than the conventional8t's,
careful attention is required to recognize the contribution of the voltage associated with lead inductance. l
The varistor voltage, because of its nonlinearity, increases only slightly as the current amplitude of the impulse
increases. The voltage from the lead inductance is strictly linear and therefore becomes large as high current amplitudes
with steep fronts are applied. For that reason, it is impractical to specify clamping voltages achieved by lead-mounted
devices with current impulses having rise times shorter than O.5t's, unless circuit geometry is very accurately controlled
and described.

7-5

a: "
~~
ent-en
a: w
~t-

AREA ~ 22 cm 2
AREA'" 0.5 cm 2
OUTPUT LEAD FROM
TRANSIENT GENERATOR

COPPER

r-::ffl-~ SURROU~~~~G

llllllliir~
. ~~~~~~i-

.-fJ....

CURRENT
PATH

VOLTAGE PROBE

--GROUND

CURRENT
PATH

b) Excessive Loop Area

a) Minimal Loop Area

. , t
.....
;. ·'·-1····'
,

!

..

A:22 cm2
S30V ~

\a:
' .~

~
.

.

....

AL' II
A:0.Scm2
480V

• • - .• <

,

i

T

~

A=0.Scm2 j
600 V··

III

~

,....

...

""

!II.: .....

. ... .

.1

,
.. ~
.

.'11'"

I:=:::
S)lS

I
III
·

I~~

I

A=22cm 2
1160V

-..•.. -

j

..

2.7kA

~

III . . .

....

--.

':I

.... ... .

t~ ~

.:"II1II

:fI·i......
:r,

. . - . . . .+-i ._ ' ... .'

~ ..:~

r--

....

~

,~

.....
~

i

.:"

..

L...

..:''''''11

.""'l

I~

_··rl.

-

2.SkA
;~
" I'

-=..

. ... ... . ... . .... i"';;
..

..:lIlIIII

...:

~
..

I::Z:::

0.2)1s

c) Current Rise of SI"

~

d) Current Rise of 0.51"

Figure 7.6 - Effect of Lead Length on "Overshoot"
To illustrate the effect of lead length on the "overshoot," two measurement arrangements were used. As shown in
Figures 7.6a and 7.6b, respectively, 0.5cm2 and 22cm2 of area were enclosed by the leads of the varistor and ofthe voltage
probe.
The corresponding voltage measurements are shown in the oscillograms of Figures 7.6c and 7.6d. With a slow current
front of 811S, there is little difference in the voltages occurring with a small or large loop area, even with a peak current of
2.7kA. With the steep front ofO.5I1S, the peak voltage recorded with the large loop is nearly twice the voltage of the small
loop. (Note on Figure 7.6d that at the current peak, L dil dt =0, and the two voltage readings are equal; before the peak, L
dildt is positive, and after, it is negative.)
Hence, when making measurements as well as when designing a circuit for a protection scheme, it is essential to be alert
to the effects oflead length (or more accurately ofloop area) for connecting the varistors. This is especially important
when the currents are in excess of a few amperes with rise times of less than IllS.

7-6

-With reasonable care in maintaining short leads, as shown in Figure 7.6a, it is possible to describe the "overshoot" effect
as an increase in clamping voltage relative to the value observed with a 8120J.ls impulse. Figure 7.7 shows a family of
curves indicating the effect between 8 and 0.5J.1s rise times, at current peaks ranging from 20 to 2000A. Any increase in the
lead length, or area enclosed by the leads, would produce an increase in the voltage appearing across the varistor terminals
- that is, the voltage applied to the protected load.

1000

~JJJJAJJ

2
800 f=t.EAD AREA< lem

111J
WAVESHAPE~

.

U>

0.5/1.5!,~

o

8/20 s

1/3~.:'i

~ 600
>

-

I

~ 400

~

~

§;

'"

z
ii:

zoo

;I;

:3u
10

40

20

60

80 100
200
400
PEAK CURRENT -AMPERES

600 8001000

2000

Figure 7.7 - Typical "Overshoot" of Lead-Mounted Varistor with Steep Current Impulses
7.3.3 DC Standby Current, ID
This current is measured with a voltage equal to the rated continuous dc voltage, VmCdc), applied across the varistor.
The circuit of Figure 7.1 is applicable where current sensing resistor R2 has a value of 10000. The test method is to set the
voltage supply, El, to the specified value with switch Sl closed and S2 in the V position. Then S2 is placed in position I
and S3 in position, ID . Sl is then opened, the test device is inserted in the test socket, and Sl is closed. The DVM reading
must be converted into current. For example, if a maximum standby current of 200J.lA is specified, the maximum
acceptable DVM reading would be 0.200V.

The measurement of dc standby current can be sensitive to the device behavioral phenomena of "break-in" stabilization
and polarization of the V-I characteristics, as described in Section 7.3.1. If the device under test has prior unipolar
electrical history, polarity indicators should be observed and test values interpreted accordingly.
The value of dc standby current also can be sensitive to ambient temperature. This is unlike varistor characteristics
measured at currents of ImA or greater, which are relatively insensitive to ambient temperatures. With VMCdc) around
85% of VN' Figure 7.8 shows the typical dc standby current ofa model Vl30LA lOA varistor in the order of 10 or 20J.lA at
room temperature. ID increases to about 80J.lA at 85°C, the maximum operating temperature without derating.
100

BO

-- -----

--

,"0_-

./

__ ,,0
:.,...:;

V'/ / V /

11'/ IV

0

/ VV/I

0

1/, VV/

0

/

/ ,I/
If /

,{tVi /,1
5

0

-9

vi
I

10-8

II

125°C

SPECIM iNt30LAtA

10-7
10-6
10-5
10-4
VARISTOR CURRENT (AMPERES, DCI

10-3

10-2

Figure 7.8 - Typical Temperature Dependence of DC Standby Current Varistor Type - V130LAIOA

7-7

a: "
~~

!III-!II

a: w
~I-

7.3.4 Capacitance
Since the bulk region of a Harris Varistor acts as a dielectric, the device has a capacitance that depends
directly on its area and varies inversely with its thickness. Therefore, the capacitance of a Harris Varistor is a
function ofits voltage and energy ratings. The voltage rating is determined by device thickness, and the energy
rating is directly proportional to volume.
Harris Varistor capacitance can be measured through use of a conventional capacitance bridge and is found
to vary with frequency, as shown in Figure 7.9. Typically, capacitance measurements are made at IMHz.
Dissipation factor also is frequency-dependent, as shown in Figure 7.10.
1400

-

0.

....Q.

1200

I-~

UJ

U

Z

',,-

;:! 1000

~

..

.... x

x x "
r---x_x

fJ.5jJs pulses up
to 8kV

Model 606
626

Prints out peak voltages, >O.5jJs duration
pulse

Zap Trap

Measures peak voltages, >2jJs duration

TR745A

Detects O.3jJs pulses, up to 3000V

·'nclusion of any manufacturer in this listing does not
constitute an endorsement nor does exclusion imply
any judgment upon same.

7.7 TEST WAVES AND STANDARDS
The varistor test procedures described in this chapter have been established to ensure conformity with applicable
standards,6 as well as to reflect the electromagnetic environment of ac(ual circuits7 which need transient protection.
Chapter 1 presented an overview of the transient environment; some additional background is presented in this section
concerning generally accepted assumptions about this environment.
7.7.1 Test Waves
A number oftest waves have been proposed, to be applied to various electronic "black boxes," in order to demonstrate
capability of survival or unimpeded performance in the environment. Table 7.4 is a partial listing of these test waves
presented to illustrate the variety of proposals rather than to be an exhaustive listing.

7-14

-Table 7.4 - Partial Listing of Existing or Proposed Test Waves
Description

Origin

Waveshapes

ANSI, IEC
IEEE Std. 472
Guide for Surge Withstand
Capability (SWC)

Amplitude

• 1.2/50115
• 8/20115
• 1.25MH repetitive
at 60Hz
6/1s decay to 50%
• 1500 source
impedance

Specified voltage Power apparatus
Specified Current
2.5kV Peak

Low-voltage ac circuits and
control lines in. substation
equipment.

Dependent on
location

Low-voltage ac circuits and
signal lines.

3kVand 6kV

High impedance circuit of
ground fault interrupters.

50 to 500A
5 to 20kA

Telephone protectors

•

ANSI/IEEE Std. C62.41-1980 • .5/1s - 100kHz
Guide on Surge Voltage in
• 1.2/50/1s voltage
Low Voltage ac Power Circuits • 8120/1s current
Ground Fault
• O.5/1S rise
Interrupters
• 100kHz ring
• 2nd peak ~ 60% first
• 500 source
impedance
ANSIllEEE C62.31-1982
Test Specifications for Gas
Tube Surge Protective Devices

Three requirements:
• 1011000/1s current
• 8120/1s current
• Linear voltage ramp
of 100, 500, 5000,
1O,000V l/1s until
sparkover

FCC Docket 19528

• Metallic

-

Typical
Application

10/560/1s

800V Peak

- 100A short-circuit
current
• Longitudinal
- 10/160/1s
- 200A short-circuit
current

Communications
equipment

1500V Peak

FCC Section 68.302
Title 47, Telecommunications

2500V Peak
• 2/1O/1s
- 1000A short-circuit
capability

Rural Electrification
Administration Spec. PE-60

• 10/1000/1s voltage
• 100V l/1s rise

30- of Protector
level

Telephone electronics

Nuclear Electromagnetic
Pulse (NEMP)

• Rectangular pulse
3ns to 10/15
• Damped sinewave
10' to 103Hz

0.1 to 1000A

Evaluation of components

• Damped sinewave
125kHz
• Unidirectional

Eoc- 50V
Isc -lOA
Eoc- 50V
Isc -lOA
Eoc- 0.5V
Isc - SA

NASA Space Shuttle

Line-powered communication
equipment

1.0 to 100A

- 2/100/15
- 300/600/15

7-15

Space Shuttle electronics

Table 7.4 - Partial Listing of Existing or Proposed Test Waves (Cont'd)
Origin

Description
Waveshapes

Amplitude

Typical
Application

MIL-STD-704

• Envelope specified,
max. duration SOps

600V Peak

Military aircraft power

ANSI/IEEE Std.
C62.33-1982
Test Specification for
Varistor SurgeProtective Devices
IEEE Std. P465.4/FD
Test Specifications for
Avalanche Junction
Semiconductor SurgeProtective Devices
ULl449
Transient Voltage
Surge Suppressors

• 8120ps current
• 1OIlOOOf.J.S current

From
Manufacturer's
specifications

Suppresors for low voltage
ac circuits, electronic
equipment

• 8120f.J.S current
• 10/ IOOOf.J.S current

From
Manufacturer's
specifications

Suppresors for electronic
equipment

• 1.2/50f.J.S voltage

6kV
125A to 3kA
dependent on
location

Suppresors for low voltage
ac circuits

• 8120ps current

A proposal also has been made to promote a transient control level concept? whereby a few selected test waves could be
chosen by common agreement between users and manufacturers. The intent being that standard test waves would
establish certain performance criteria for electronic circuits, without resorting to a multiplicity of test waves, each
attempting to simulate a particular environment.

7.7.2 Source Impedance
The effective impedance of the circuit which introduces the transient is an extremely important parameter in designing
a protective scheme. Impedance determines the energy and current-handling requirements of the protective device.
Historically, the approach to transient withstand capability was to apply a voltage wave to a device and to ascertain that
no breakdown occurred. Typically, the device offered high impedance to the impulse, so that no significant current would
flow (unless breakdown occurred), and the source impedance was unimportant. But if a transient suppressor is applied,
especially a suppressor of the energy-absorbing type, the transient energy is then shared by the suppressor and the rest of
the circuit, which can be described as the "source".
As in the case of waveshapes, various proposals have been made for standardizing source impedances. The following
list summarizes the various proposals intended for ac power lines:
1. The Surge Withstand Capability (SWC) standard specified a 1500 source.
2. The Ground Fault (UL-GFCI) standard is 500 source. 8
3. The Transient Control Level (TCL) proposals of Martzloff et aF include a 500 resistor in parallel with a 50pH
inductor.
4. The installation category concept of ANSI/IEEE Standard C62.41-1980 implies a range of impedances from I to
500 as the location goes from outside to inside.
5. The FCC regulation for line-connected telecommunication equipment implies a 2.50 source impedance. 9 However,
the requirement of the FCC is aimed at ensuring a permanent "burning" of a dielectric puncture and does not
necessarily imply that the actual source impedance in the real circuits is 2.50.
6. Reported measurements lO indicate the preponderance of the inductance in branch circuits. Typical values are JlH per
meter of conductors.

7-16

7.

There is no agreement among the above proposals on a specific source impedance. Examining the numbers closer,
one can observe that there is a variance between 2.Sohms to about SOohms. Going back to ANSI/IEEE Standard
C62.41-1980 - by using the OCV (open circuit voltage) and SCI (short circuit current) for the different location
categories, one can calculate a source impedance.

Any practical power circuit will always have some finite impedance due to the resistance and inductance of the power
line and distribution transformer. Figure 7.1S shows representations of the surge source impedance implied in the
environment description of ANSI/IEEE C62.41-1980.
The impedance of industrial or commercial systems generally supplied by underground entrances, or a separate
substation of relatively large kVA rating, tends to be low, and the injection of any lightning transients occurs at a remote
point. This results in lower transient peaks than those that can be expected in residential circuits, but the energy involved
may be, in fact, greater. Therefore, transient suppressors intended for industrial use should have greater energy-handling
capability than the suppressors recommended for line-cord-powered appliances.
Clearly, the industry standards have not been able to agree on a single value of the source impedance, for several
reasons. When a transient suppressor is being selected for a particular application, there is a need for engineering judgment
based on a knowledge of the function, and the capability of the device.
CATEGORY A RING WAVE
CATEGORY B RING WAVE
CATEGORY B IMPULSE
CATEGORY C IMPULSE
Figure 7.15 -

6kV1200A = 300
6kV /SOOA = 120
6kV/3kA = 20
IOkV /lOkA = 10

Source Impedance at Different Location Categories in Low Voltage AC Systems (up to 1000V)
Note: IEEE categories A, B & C defined on page 9-7.

REFERENCES
1. Fisher, F.A., "Overshoot - A Lead Effect in Varistor Characteristics," Report 78CRD, General Electric,
Schenactady, N.Y., 1978.
2. Heller, B. and A. Veverka, Surge Phenomena in Electrical Machine, ILIFFE Books Ltd., London, 1968.
3. Greenwood, Allen, Electrical Transients in Power Systems, Wiley Interscience, New York, 1971.
4. Craggs, J.D. and J.M. Meek, High Voltage Laboratory Techniques, Buttersworth Scientific Publications, London,
19S4.
S. Martzloff, F.D., 'Transient Control Level Test Generators," Report 77CRD241, General Electric, Schenectady,
N.Y., 1977.
6. Test Specifications for Varistor Surge-Protective Devices, ANSI/IEEE Std. C62.33, 1982.
7. Martzloff, F.D., and F.A. Fisher, "Transient Control Level Philosophy and Implementation - The Reasoning Behind
the Philosophy," 77CHI224-SEMC, Proceedings of the 2nd Symposium on EMC, Montreux, June 1977.
8. "Standard for Safety: Ground Fault Circuit Interrupters, "UL943, Underwriters Laboratories, May 12, 1976.
9. "Longitudinal Voltage Surge Test #3, "Code of Federal Regulations, Section 68.302( e), Title 47, Telecommunications.
10. F.D. Martzloff, "The Propagation and Attenuation of Surge Voltages and Surge Currents in Low-Voltage AC
Circuits," IEEE Transactions on Power Apparatus and Systems, PAS-I02, pp. 1163-1170, May 1983.

7-17

8
HARRIS MOV QUALITY & RELIABILITY
QUALITY STATEMENT
"Harris is committed to being a company
of the highest quality in every aspect
of its business activity"
John T. Hartley
Chainnan, Harris Corporation

INTRODUCTION
Success in the metal oxide varistor (MOV) industry means more than simply meeting or exceeding the demands oftoday's market. It
also includes anticipating and accepting the challenges of the future. It results from a process of continuing improvement and
evolution, with perfection as the constant goal.
Harris Semiconductor's commitment to supply only top value varistors has made quality improvement a mandate for every person in
our work force - from designer to manufacturing operator, from hourly employee to corporate executive. Price is no longer the only
determinant in marketplace competition. Quality, reliability, and perfonnance enjoy significantly increased importance as measures
of value in MOVs.
Quality in varistors cannot be added on or considered after the fact. It begins with the development of capable process technoiogy and
product design. It continues in manufacturing, through effective controls at each process or step. It culminates in the delivery of
products which meet or exceed the expectations of the customer.
VISION
Total Quality, every minute of every day, for everyone who depends on our perfonnance.

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CHARTER
To be the preferred supplier of high perfonnance semiconductors for analog, digital signal processing and power applications.
Throughout the 80's the pace of change of what has been considered 'acceptable' quality has been breathtaking. It has been a transition
from percentage defective, to under 100 ppm, undertaken only by those who are still in business. The forces of change have been those
of customer expectation and natural selection. Harris varistors have followed a path of strong and steady continuous improvement
which today results in world-class end-product quality and reliability.
The Total Quality Management principles used to create the Quality System, within which Harris varistors are made, are based on five
principles. Emanating from the top of the Corporation, they are evident throughout the Semiconductor Sector, and affect the conduct
of business in a profound way.
HARRIS TOTAL QUALITY MANAGEMENT PRINCIPLES
Customer Focus
Customer satisfaction is the paramount purpose of all company activities. Meeting the requirements and value expectations of our
internal and external customers is the primary task of every employee.
Continuous Improvement
Our planning activities will recognize continuous improvement as a primary business objective. Our products and services, together
with the processes and systems which produce them, will be world class.

8-1

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Employee Involvement
We will provide an environment and related value system in which all Harris people are personally involved, individually and
as team members, in establishing and achieving quality goals.

SuppHer Partnerships
We will develop and maintain mutually beneficial partnerships with suppliers who share our commitment to achieving increased
levels of customer satisfaction through continuing improvements in quality, service, timelines and cost.

Highest Standards of Conduct, Ethics and Integrity
We will conduct our business in strict compliance with applicable laws, rules and regulations; with honesty and integrity; and
with a strong commitment to the highest standards of business ethics.

ISO 9000
Preparing for ISO 9000 certification means that a company as a whole looks at its total system; operational waste is eliminated
and quality procedures are firmly put in place from the grass roots level all the way to the board room. This certification focuses
on the concept of stating what you do, documenting what you do and then doing what you say. Simply put, this means it is
necessary to document the operation from when raw material is purchased right through to the finished product. This quality
management system begins with the management responsibility, including the policy statement and explanation. It also requires
that the authority and responsibility be clearly defined for all functions. ISO 9000 assures a system approach to quality control.
It represents a basic look at the business that is a very good way to view manufacturing and operations. (Figure 1)
Obtaining ISO certification really stresses the quality concepts of supplier quality, supplier partnership, and manufacturing
control. The pursuit of this international certification clearly focuses on process and as a result empowers all company employees through the documentation and understanding that is necessary in becoming certified.
The ISO 9000 series of standards are generic in nature. The United States has adopted the ISO series word for word as the ANSU
ASQC Q90 series. ISO 9000 and ISO 9004 are basically glossary documents. A company can really only be certified to ISO
9001, ISO 9002 and ISO 9003.
The Harris MOV facility has been a registered ISO 9001 company since 1989. ISO 9001 is a model for quality assurance in the
design/development, production, installation and servicing. This certification requires the demonstration of a supplier's capability to design, produce, install and service a product. ISO 9001 certification requires verification by independent auditors four
times a year to ensure compliance.

RAW
MATERIALS

PRODUCT
(SERVICES)

C
U
S
T

o

M

E

R

PROCESS CONTROL
DOCUMENTCONTROL-SYSTEMS-PROCEDURES·RECORDS
Figure 1. ISO 9000 Logic

8·2

THE ROLE OF THE QUALITY ORGANIZATION
The emphasis on building quality into the design and manufacturing processes of a product has resulted in a significant refocus
of the role of the Quality organization. In addition to facilitating the development of SPC and DOX programs and working with
manufacturing to establish control charts, Quality professionals are involved in the measurement of equipment capability,
standardization of inspection equipment and processes, analysis of inspection data and feedback to the manufacturing areas,
coordination of efforts for process and product improvement, optimization of raw materials quality, and the development of
quality improvement programs with vendors.
At critical manufacturing operations, process and product quality is analyzed through random statistical sampling and product
monitors. The Quality organization's role is changing from policing quality to leadership and coordination of quality programs
or procedures through auditing, sampling, consulting, and managing Quality Improvement projects.
To support specific market requirements, or to ensure conformance to military or customer specifications, the Quality
organization still performs many of the conventional quality functions. But, true to the philosophy that quality is everyone's job,
much of the traditional on-line measurement and control of quality characteristics is where it belongs - with the people who
make the product. The Quality organization is there to provide leadership and assistance in the deployment of quality techniques, and to monitor progress.

THE IMPROVEMENT PROCESS

t

STAGEIV

I

II

PRODUCT
OPTIMIZATION

IMPACTON
PRODUCT

STAGE III

auAUTY

PROCESS
OPTIMIZATION
STAGED
PROCESS
CONTROL

STAGE I
PRODUCT
SCREENING
SOPHISTICATION OF
aUAUTYTECHNOLOGY

Figure 2. Stages of Statistical Quality Technology
Harris Semiconductor's quality methodology is evolving through the stages shown in Figure 2. In 1985 we embarked on a
program to move beyond Stage I, and we are currently in the transition from Stage II to Stage ill, as more and more of our people
become involved in quality activities. The traditional "quality" tasks of screening, inspection, and testing are being replaced by
more effective and efficient methods, putting new tools into the hands of all employees.

HARRIS STANDARD FLOWS
Harris Semiconductor offers a variety of standard product flows which cover the myriad of application environments our
customers experience. All of these grades have one thing in common. They result from meticulous attention to quality, starting
with design decisions made during product development and ending with the labeling of shipping containers for delivery to our
customers.
Wherever feasible, and in accordance with good value engineering practice, the MOV user should specify device grades based
on the standard Harris manufacturing flow. These are more than adequate for the overwhelming majority of applications and
may be utilized quite effectively if the user engineer bases designs on the standard data sheet, military drawing or slash sheet
(as applicable) electrical limits.
Some of the more important advantages gained by using standard as opposed to custom flows are as follows:
• Lower cost than the same or an equivalent flow executed on a custom basis. This results from the higher efficiency
achieved with a constant product flow and the elimination of such extra cost items as special fixturing, test programs,
additional handling and added documentation.

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• Faster delivery. The manufacturer often can supply many items from inventory and, in any case, can establish and
maintain a better product flow when there is no need to restructure process and/or test procedures.
• Increased confidence in the devices. A continuing flow of a given product permits the manufacturer to monitor trends
which may bear on end-product performance or reliability and to implement corrective action, if necessary.
Reduction of risk. Since each product is processed independent of specific customer orders, the manufacturer absorbs
production variability within its scheduling framework without major impact on deliveries. In a custom flow, a lot failure late in
the production cycle can result in significant delays in delivery due to the required recycling time.
Despite the advantages of using standard flows, there are cases where a special or custom flow is mandatory to meet design or
other requirements. In such cases, the Harris Marketing groups stand ready to discuss individual customer needs and, where
indicated, to accommodate appropriate custom flows.

DESIGNING FOR MANUFACTURABILITY
Assuring quality and reliability in MOVs begins with good product and process design. This has always been a strength in
Harris Semiconductor's quality approach. We have a very long lineage of high reliability, high performance products that have
resulted from our commitment to design excellence. All Harris products are designed to meet the stringent quality and
reliability requirements of the most demanding end equipment applications, from military and space to industrial and
automotive. The application of new tools and methods has allowed us to continuously upgrade the design process.
Each new design is evaluated throughout the development cycle to validate the capability of the new product to meet the end
market performance, quality, and reliability objectives.
The validation process has four major components:
1.
2.
3.
4.

Design simulation/optimization
Layout verification
Product demonstration
Reliability assessment.

CONTROLLING AND IMPROVING THE MANUFACTURING PROCESS SPC/DOX
Statistical process control (SPC) is the basis for quality control and improvement at Harris Semiconductor. Harris manufacturing
people use Shewhart control charts to determine the normal variabilities in processes, materials, and products. Critical process
variables are measured and control limits are plotted on the control charts. Appropriate action is taken if the charts show that an
operation is outside the process control limits or indicates a trend toward the limit. These same control charts are powerful tools
for use in reducing variations in processing, materials, and products.
SPC is important, but stilI considered only part of the solution. Processes which operate in statistical control are not always
capable of meeting engineering requirements. The conventional way of dealing with this in the semiconductor industry has been
to implement 100% screening or inspection steps to remove defects, but these techniques are insufficient to meet today's
demands for the highest reliability and perfect quality performance.
Harris still uses screening and inspection to "grade" products and to satisfy specific customer requirements. However,
inspection and screening are limited in their ability to reduce product defects to the levels expected by today's buyers. In
addition, screening and inspection have an associated expense, which raises product cost.
Harris engineers are, instead, using Design of Experiments (DOX), a scientifically disciplined mechanism for evaluating and
implementing improvements in product processes, materials, equipment, and facilities. These improvements are aimed at
reducing the number of defects by studying the key variables controlling the process, and optimizing the procedures or design
to yield the best result. This approach is a more time-consuming method of achieving qUality perfection, but a better product
results from the efforts, and the basic causes of product nonconformance can be eliminated.
SPC, DOX, and design for manufacturability, coupled with our 100% test flows, combine in a product assurance program that
delivers the quality and reliability performance demanded for today and for the future.

8-4

MEASUREMENT
Harris facilities, engineering, manufacturing, and product assurance are supported by the Analytical Services Laboratory.
Organized into chemical or microbeam analysis methodology, staff and instrumentation from both labs cooperate in fully
integrated approaches necessary to complete analytical studies. The capabilities of each area are shown below.
SPECTROSCOPIC METHODS: Colorimetry, Optical Emission, Ultraviolet Visible, Fourier Transform-Infrared, Flame
Atomic Absorption, Furnace Organic Carbon Analyzer, Mass Spectrometer.
CHROMATOGRAPHIC METHODS: Gas Chromatography, Ion Chromatography.
THERMAL METHODS: Differential Scanning Colorimetry, Thermogravimetric Analysis, Thermomechanical Analysis.
PHYSICAL METHODS: Profilometry, Microhardness, Rheometry.
CHEMICAL METHODS: Volumetric, Gravimetric, Specific Ion Electrodes.
ELECTRON MICROSCOPE: Transmission Electron Microscopy, Scanning Electron Microscope.
X-RAY METHODS: Energy Dispersive X-ray Analysis (SEM), Wavelength Dispersive X-ray Analysis (SEM), X-ray
Fluorescence Spectrometry, X-ray Diffraction Spectrometry.
SURFACE ANALYSIS METHODS: Scanning Auger Microprobe, Electron Spectroscope/Chemical Analysis, Secondary Ion
Mass Spectrometry, Ion Scattering Spectrometry, Ion Microprobe.
The department also maintains ongoing working arrangements with commercial, university, and equipment manufacturers'
technical service laboratories, and can obtain any materials analysis in cases where instrumental capabilities are not available
in our own facility.

FIELD RETURN PRODUCT ANALYSIS SYSTEM
The purpose of this system is to enable Harris' Field Sales and Quality operations to properly route, track and respond to our
customers' needs as they relate to product analysis. The Product Failure Analysis Solution Team (pFAST) consists of the group
of people who must act together to provide timely, accurate and meaningful results to customers on units returned for analysis.
This team includes the salesman or applications engineer who gets the parts from the customer, the PFAST controller who
coordinates the response, the Product or Test Engineering people who obtain characterization andlor test data, the analysts who
failure analyze the units, and the people who provide the ultimate corrective action. It is the coordinated effort of this team,
through the system described in this document that will drive the Customer responsiveness and continuous improvement that
will keep Harris on the forefront of the semiconductor business.
The system and procedures define the processing of product being returned by the customer for analysis performed by Product
Engineering, Reliability Failure Analysis andlor Quality Engineering. This system is designed for processing "sample" returns,
not entire lot returns or lot replacements.
The philosophy is that each site analyzes its own product. This applies the local expertise to the solutions and helps toward the
goal of quick tum time.
Goals: quick, accurate response, uniform deliverable (consistent quality) from each site, traceability.
The PFAST system is summarized in the following steps:
1) Customer calls the sales rep about the unit(s) to return.
2) Fill out PFAST Action Request see the PFAST form in this section. This form is all that is required to process a Field Return of
samples for failure analysis. This form contains essential information necessary to perform root cause analysis. (See Figure 5).
3) The units must be packaged in a manner that prevents physical damage. Send the units and PFAST form to the appropriate PFAST
controller. This location can be determined at the field sales office or rep using "look-up" tables in the PFAST document.
4) The PFAST controller will log the units and route them to ATE testing for data log.
5) Test results will be reviewed and compared to customer complaint and a decision will be made to route the failure to the appropriate
analytical group.
6) The customer will be contacted with the ATE test results and interim findings on the analysis. This may relieve a line down situation
or provide a rapid disposition of material. The customer contact is valuable in analytical process to insure root cause is found.

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7) A report will be written and sent directly to the customer with copies to sales, rep, responsible individuals with corrective actions and
to the PFAST controller so that the records will capture the closure of the cycle.
8) Each report will contain a feedback form (stamped and preaddressed) so that the PFAST team can assess their performance based on
the customers assessment of quality and cycle time.
9) The PFAST team objectives are to have a report in the customers hands in 28 days, or 14 days based on agreements. Interim results are
given realtime.

Failure Analysis Laboratory
The Failure Analysis Laboratory's capabilities encompass the isolation and identification of all failure modes/failure mechanisms, preparing comprehensive technical reports, and assigning appropriate corrective actions.
Failure analysis is a method of enhancing product reliability and determining corrective action. It is the final and crucial step
used to isolate potential reliability problems that may have occurred during reliability stressing. Accurate analysis results are
imperative to assess effective corrective actions. To ensure the integrity of the analysis, correlation of the failure mechanism to
the initial electrical failure is essential.
A general failure analysis procedure has been established. The analysis procedure was designed on the premise that each step
should provide information on the failure without destroying information to be obtained from subsequent steps. The exact steps
for an analysis are determined as the situation dictates. (See Figures 3 and 4). Records are maintained by laboratory personnel
and contain data, the failure analyst's notes, and the formal Product Analysis Report.

Figure 3. Non-Destructive

Figure 4. Destructive

8-6

:II

HARRIS
SEMICONDUCTOR

Request #
Customer Analysis #

PFAST ACTION REQUEST
Date:
CuSTOMER

ORIGINATOR

No.
TVPE/PART No.

LoCATION/PHONE

loCATION

DEVICE

PURCHASE ORDER

No.

No.

QUANTITY RECEIVED

SAMPLES RETURNED

THE COMPIEI'ENrSS AND TIMELY RFSPONSE OF THE EVALUATION IS DIRECTLY RElATED TO THE COMPLETENESS
OF THE DATA PROVIDED. PLEAsE PROVIDE All. PERTINENT DATA. ATTACH ADDITIONAL SHEETS IF NECESSARY.

DETAILS

TYPE OF PROBLEM

1. CI INCOMING INSPECTION
CI 100% ScREEN CI SAMPLE iNSPECTION

TEsT CONDITIONS RElATING TO FAILURE
TEsTER USED (MFGR/MODEL)
TEsT TEMPERATIJRE
TEsT TIME:
CoNTINUOUS TEsr
ONE SHOT (f

o
o
o

--

No. OF REJECTs
No. TEsTED
ARE RESULTS REPRFSENTATIVE OF PREVIOUS LOTS?
DYES
DNa
BRIEF DESCRIPTION OF EVALUATION
AND RFSULTS ATTACHED
2.
IN PROCESS/MANUFACTIJRING FAILURE
BOARD CHEcKOUT
SYSTEM CHEcKOUT
FAILED ON TuRN-ON
HOURS OPERATION
FAILED AFTER
WAS UNIT RETESTED UNDER INCOMING INSPECTION
CONDITIONS?
NO
YES
CI BRIEF DESCRIPTION OF HOW FAILURE WAS ISOLATED
TO COMPONENT ATTACHED
3. 0 FIELD FArLURE
FAILED AFTER
HOURS OPERATION
EsTIMATED FAILURE RATE _ _% PER 1000 HOURS

--

o

o

o
o
o

OF REJECT

(WII .... appropriate IOriallz... lIS IUd apeclry ror each)

0

o
o

=__ SEC)

DESCRIPTION OF ANY OBSERVED CONDITION TO
WInCH FAILURE APPEARS SENSITIVE:

o

1.0 DC FAILURES
OPENS 0 SHORTS 0 lEAKAGE CI STRESS
POWER DRAIN 0 INPUT UlVEL 0 OUTPUT LEVEL
LIsT OF FORCING CONDITIONS AND MEASURED
RFSULTS FOR EACH PIN IS ATTACHED
POWER SUPPLY SEQUENCtNG ATTACHED
2.0 ACFAlLURES
LIsT FAIUNG CHARACTERISTICS

o
o
o

--

o

o

o

--

ENOUSER
LocATION
AMBIENT TEMPERATURE
C
MIN.
C
MAx.
C
REI... HUMIDITY
%
END USER FAILURE CORRFSPONDENCE ATTACHED

--

ADDRESS OF FAIUNG LocATION (IF APPUCABLE)

--

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ACTION REQUESTED BY CUSTOMER

SPECIFIC ACTION REQUESTED
IMPACT OF FAILED UNITS ON CUSTOMER'S SITIJATlON:

_ii:

---

CUSTOMER CoNTACTS WrIT! SPECIFIC KNoWLEDGE OF REJECTS
NAME
PosITION
PHONE

ATTACHED:
LIsT OF POWER SUPPLY AND DRIVER LEvELS
(Include pictures of waveforms).
LIsT OF OUTPUT LEVELS AND WADING CONDITIONS
INPUT AND OUTPUT TIMING DIAGRAMS
DESCRIPTION OF PATTERNS USED
(If not standard patterns, give very complete
description including address sequence).
3.0 PROM PROGRAMMING FAILURES
ADDRESS OF FAILURES
PROGRAMMER USED (MFG/MODEI./REV. No.)

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4.0 I'HYsICAIJAssEMBLY RElATED FAILURES
SEE CoMMENTS BELOW 0 SEE ATTACHED

o

Additional Comments:

Figure

5.

PFAST Action Request
I

8-7

ACCREDIATIONS
The Harris quality system meets or exceeds a wide range of standards, which indicates, together with the knowledge that each
standard involves surveillance audits, up to four times per year, that the quality system is complete, and its integrity is being
maintained.
The European Standard harmonization agency, CENELEC Electronic Component Committee,
CECCOO 100
awarded Harris their "Certificate of Approval of Manufacture". Rej'n #M01O, in 1986.
ISO 9000 Part 1

The quality system meets all of the requirements ofISO 9000 Part 1(ISO 9001).

MilQ9858A,
MiI-I-45208

Harris is a MiI-R-83530 QPL supplier and conforms to these standards, as well as those referenced by
them.

Certain product certifications with UL, CSA, VDE, IEC, JEDEC, DESC and the CECC QPL system also exist.

Training
The basis of a successful transition from conventional quality programs to more effective, total involvement is training.
Extensive training of personnel involved in product manufacturing began in 1984 at Harris, with a comprehensive development
. program in statistical methods. Using the resources of the private consultants, and internally developed programs, training of
over engineers, supervisors, and operators/technicians has been completed.
Nearly 200 operators, 10 supervisors, and more than 25 engineers have been trained in SPC methods, providing them with tools
to improve the overall level of uniformity of Harris products. 25 engineers have received training in DOX methods: learning to
evaluate changes in process operations, set up new processes, select or accept new equipment, evaluate materials, select vendors,
compare two or more pieces of equipment, and compare two or more process techniques.
Over the past four years, Harris has also deployed a comprehensive training program for hourly operators and supervisors injob
requirements and functional skills. All hourly manufacturing employees participate (see Table 1).
Table 1. Summary of Training Programs
AUDIENCE

LENGTH

TOPICS COVERED

SPC

COURSE

Manufacturing Operators

8 Hours

Basic Philosophy, Statistical Calculations Graphing Techniques, Pareto Charts,
Control Charts

SPC

Manufacturing
Supervisors

21 Hours

Basic Philosophy, Stalistical Calculations Graphing Techniques, Pareto Charts,
Control Charts, Testing for Inspector Agreement, Cause & Effect Diagrams, I
& 2 Sample Methods

SPC

Engineers and
Managers

48 Hours

Basic Philosophy, Graphical Methods, Control Charts, Rational Subgrouping,
Variance Components, I & 2 Sample Methods, Pareto Charts, Cause & Effect
Diagrams

DOX (Design of Experiments)

Engineers and
Managers

88 Hours

Factorial Designs, Fractional Factorial Designs, Blocking Designs, Variance
Components, Computer Usage, Normal Probability Plotting

Continuous Improvement
Methods

Manufacturing
Supervisors

12 Hours

Basic Philosophy, Pareto Analysis, Imagineering, Run Charts, Cause & Effect
Diagrams, Histograms, Ideas of Control Charts

SPC-The Essentials

Department-Level
WorkGroups

20 Hours

Basic Philosophy, of Continuous Improvement, Imagineering Pareto Charts,
Cause & Effect Diagrams, Flow Charts, Graphical Display, Control Charts,
Ideas of Experiment

In addition to the already widespread use of statistics, SPC and DOX the following tools are now being widely distributed
throughout the whole workforce.
•
•
•
•
•
•
•
•

Preventative Maintenance
P.M.
Total Productive Maintenance
T.P.M.
EM.E.A.
Failure Mode Effect Analysis
A.C.T. P.T.M. Applying Concurrent Teams to Product to Market
A.EE.
Agreement for Excellence
Process Characterization Skills
Project Management
Concurrent Engineering

8-8

~-

RELIABILITY
The Harris Varistor is a rugged, reliable voltage transient suppressor designed to improve the reliability of electronic systems.
Proper system design with this varistor, as detailed in other parts of this manual, will clamp transient voltages to a level
compatible with long-life of the electronic system. To assure Harris Varistor reliability, Harris performs extensive process and
quality control monitoring. This is accomplished via a combination of 100%, periodic, and lot testing. Both parametric and reliability characteristics are controlled in this manner.
For example, Harris Varistors are classified into two categories; a "line voltage" type (above 115V RMS) and a "low voltage"
type (below 115V RMS). Reliability evaluation has been conducted on both types under the conditions summarized below:
Table 2. Reliability Evaluation
STRESS

TEST CONDITION

Voltage

AC Bias, DC Power

Temperature

85"C,125°C

Energy

Pulse

Storage

125° C, 15<1 C

Humidity

85OC, 85% RH

Mechanical

Solderability, Terminal Strength, Drop
Shock, Vibration

As improved products, processes, and test procedures evolve, the applicability of past data to reliability assessment changes.
Thus, the data presented in this chapter represents a "snapshot in time" of data applicable to the Harris Varistors being
manufactured now and for the anticipated future. The test data has been generated at very high stress levels, at or beyond
maximum ratings, to confirm the product'S ability to meet these ratings and to obtain the most information in the shortest time
period. Results of ac voltage and de power bias tests are used in the generation of models from which the expected life as a
function of stress can be obtained.
A general "High Reliability" series of Harris Varistors is also available. These are specially stress-screened devices for high
reliability applications.
High Reliability Harris Varistors are the latest step in increased product performance, and are available for applications requiring
quality and reliability levels consistent with military test methods.
Reliability Assessment and Enhancement
At Harris Semiconductor, reliability is built into every product by emphasizing quality throughout manufacturing. This starts
by ensuring the excellence of the design, layout, and manufacturing process. The quality of the raw materials and workmanship
is monitored using statistical process control (SPC) to preserve the reliability of the product. The primary and ultimate goal of
these efforts is to provide full performance to the product specification throughout its useful life. Product reliability is
maintained through the following sources: Qualifications, In-Line Reliability Monitors, Failure Analysis.
Qualifications
Qualifications at Harris de-emphasize the sole dependence on production product which is only available late in the
development cycle. The focus is primarily on the use of test vehicles to establish design ground rules for the product and the
process that will eliminate any wear-out mechanisms during the useful life of the product However, to comply with the military
requirements concerning reliability, product qualifications are perfonned.
In-line Reliability Monitors
In-line reliability monitors provide immediate feedback to manufacturing regarding the quality of workmanship, quality of raw
materials, and the ultimate reliability implications. The rudimentary implementation of this monitoring is the "First Line of
Defense;' which is a passl fail acceptance procedure based on control charts and trend analysis. The second level of monitoring
is referred to as the ''Early Warning System" and incorporates wafer level reliability concepts for extensive diagnostic and
characterization capabilities of various components that may impact the device reliability or stability. The quick feedback from
these schemes allows more accurate correlation to process steps and corrective actions.

8-9

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ProductJPackage Reliability Monitors
Reliability of finished product is monitored extensively. under a program called Matrix II, III monitor. All major technologies
are monitored.
Matrix II Longer duration test, much like requalification. 'The sample sizes are reduced in number and frequency, yet meet or
exceed the JEDEC Standard 29. Stresses Operating Life, Storage, THB, Autoclave, Temp Cycle, and 'Thermal Shock.
Matrix III Package specific test. Tests Solderability, Lead Fatigue, Physical Dimensions, Brand Adhesion, Flammability, and
Constant Acceleration. Data from these Monitor Stress Test provides the following information:
• Routine reliability monitoring of products by technology and package styles.
• Data base for determining FIT Rates and Failures Mode trends used drive Continuous Improvement.
• Major source of reliability data for customers.
• Customers have used this data to qualify Harris products.

RELIABILITY FUNDAMENTALS
Reliability, by its nature, is a mixture of engineering and probability statistics. This combination has derived a vocabulary of
terms essential for describing the reliability of a device or system. Since reliability involves a measurement of time, it is necessary to accelerate the failures which may occur. This, then, introduces terms like "activation energy" and "acceleration factor,"
which are needed to relate results of stressing to normal operating conditions (see Table 3). Also, to assess product reliability
requires failures. Therefore,· only a statistical sample can be used to determine the model of the failure distribution for the
entire population of product.
Failure Rate Calculations
Reliability data for products may be composed of several different failure mechanisms and requires careful combining of
diverse failure rates into one comprehensive failure rate. Calculating the failure rate is further complicated because failure
mechanisms are thermally accelerated at varying rates and thereby have differing accelerating factors. Additionally, this data is
usually obtained a variety of life tests at unique stress temperatures. The equation below accounts for these considerations and
then inserts a statistical factor to obtain the confidence interval for the failure rate.

F1T= (B
i

Xi

~1 . ~

)

x

109

xM

TOHs AFu

J=1

B = # of distinct possible failure mechanisms
K

= # of life tests being combined

XI = # of failures for a given failure mechanism
i =I, 2, ... B
TOGs

= Total device hours of test time (unacceler-

AFu

= Acceleration factor for appropriate failure

ated) for Life Testj
mechanism i

=1,2, ... K

M = Statistical factor for calculating the upper
confidence limit (M is a function of the total number of failures and an estimate of
the standard deviation of the failure rates)
In the failure rate calculation, Acceleration Factors (AFu) are used to derate the failure rate from thermally accelerated Life
Test conditions to a failure rate indicative of use temperatures. Though no standards exist, a temperature of +55°C has been
popular and allows some comparison of product failure rates.

8-10

Acceleration Factors
The Acceleration Factors (AP) are detennined from the Arrhenius Equation. This equation is used to describe physiochemical
reaction rates and is an appropriate model for expressing the thermal acceleration of semiconductor failure mechanisms.

AF= EXP

[~ (T~se

Ts~ess) ]

-

AF = Acceleration Factor
EA = Thermal Activation Energy in eV
K = Boltzmann's Constant (8.62 x 10-5 eVfJK)
Both Tuse and Tstress (in degrees Kelvin) include the internal temperature rise of the device and therefore represent the
junction temperature. With the use of the Arrhenius Equation, the thermal Activation Energy (EA) term is a major influence on
the result. This term is usually empirically derived and can vary widely.
Activation Energy
To detennine the Activation Energy (EA) of a mechanism you must run at least two (preferably more) tests at different stresses
(temperature and/or voltage). The stresses will provide the time to failure (Tt) for the populations which will allow the
simultaneous solution for the Activation Energy by putting the experimental results into the following equations.
In (tf2)

=

C +

EA

KT2
Then, by subtracting the two equations, the Activation Energy becomes the only variable, as shown.
In(tn) -In(td

=EA/k(lffl-lff2)

EA = K* ((1n(tn) -In(tn))I(lffl - Iff2»
The Activation Energy may be estimated by graphical analysis plots. Plotting In time and In temperature then provides a
convenient nomogram that solves (estimates) the Activation Energy.
All Harris Reliability Reports from qualifications and Group Cl (all high temperature operating life tests) will provide the data
on all factors necessary to calculate and verify the reported failure rate (in FITs) using the methods outlined in this primer.

c>
z ....
et:::::;

~iii

-et
...1et...l

;:)w

aD:

8-11

Table 3. Glossary of Terms
TERMSIDEFINITIONS

UNITSIDESCRIPTION

FAILURE RATE A.

FIT - Failure In Time

For Semiconductors, usually expressed in FITs.
Represents useful life failure rate (which implies a constant
failure rate).
FITs are not applicable for infant mortality or wearout
failure rate expressions.

1 FIT - 1 failure in 109 device hours.
Equivalent to 0.0001 %11000 hours
FITs =
# Failures
x 109 x m
i Devices x # hours stress x AF
m - Factor to establish Confidence Interval
109 - Establishes in terms of FITs
AF - Acceleration Factor at temperature for a given failure
mechanism

MTTF - Mean Time To Failure

Mean Time is measured usually in hours or years.

For semiconductors, MTTF is the average or mean life
1 Year = 8760 hours
expectancy of a device.
When working with a constant failure rate the MTTF can be
If an exponential distribution is assumed then the mean time calculated by taking the reciprocal of the failure rate.
to fail of the population will be when 63% of the parts have MTTF = IJA. (exponential model)
failed.
Example: =10 FITs at +55°C
The MTTF is: MTTF = IJA. = 0.1 x 109 hours
= 100M hours
CONFIDENCE INTERVAL (C. I.)

Example:

Establishes a Confidence Interval for failure rate
predictions. Usually the upper limit is most significant in
expressing failure rates.

"10 FITs @ a 95% C. I. @ 55°C" means only that you are
95% certain the FITs <10 at +55°C use conditions.

AC BIAS RELIABILITY
Many applications of Harris Varistors are as transient suppressors on an ac line. The varistor is connected across the ac line
voltage and is biased with a constant amplitude sinusoidal voltage. If the varistor current increases with time, the power
dissipation will also increase, with the ultimate possibility of thermal runaway and varistor failure. Because of this possibility,
an extensive series of statistically designed tests were performed to determine the reliability of this type of varistor under ac
bias combined with high levels of temperature stress. This test series contained over one million device hours of operation at
temperatures up to 150°C. The average duration of testing ranged from 7000 hours at low stress to 495 hours at high stress.
The definition offailure is a shift in VN exceeding ±10%. Although this type of varistor is still functioning norrnally after this
magnitude of shift, devices at the lower extreme of VN tolerance will begin to dissipate more power. As previously explained,
this could ultimately lead to failure. This choice of failure definition, in combination with the lower stresses found in applications, will provide life estimates adequate for most design requirements.
The results of these accelerated high level tests showed that the response of the Harris Varistor is an excellent fit to the
Arrhenius model, i.e., the expected mean life is logarithmically related to the inverse of the absolute temperature. This type of
Arrhenius model response is shown in Figure 6 for the line voltage and the low voltage types of varistors. As shown in the
illustrations this response can be described in the following general equation.
- A.exp ( -T)
AbK
Where:
Ab = Mean Time to Failure
E = Activation Energy (eV)
K = Boltzmann's Constant (8.63 x 10-5 eVfK)
T = Absolute Temperature (K)
A =Constant

8-12

..,-

_

MAX VOLTAGE STRESS
.~~"

108 _

..

'

80% MAX VOLTAGE
STRESS ESTIMATE

108

UJ

a:

50 35
W

Ii.

10 :::J
S

~
w

::Ii

1031-+-ii"OfTH-+I DEVICE TYPE: V130LA

~

_

MAX VOLTAGE STRESS

.~~~~

80% MAX
VOLTAGE STRESS

81 107

.....

:::>
0

~106

.. .... ...... ....... --,

w
:::J 105

Ii.

.'

z

l.t.

 ±1 D%

FAILURE CRITERIA: I!.VN > ±10%

13C 120 100 90 80 70 60 50 40
180 160
170 150140125
AMBIENT TEMPERATURE IN °c

......

-

170 150 130 1110100 gO 80 70 60 so 40
180 160 140 120
AMBIENT TEMPERATURE IN °c

3025

3025

(b) Low Voltage Harris Varistor

(a) Line Voltage Harris Varistor

Figure 6. Arrhenius Models of Varistor Mean Life vs Temperature
This type of statistical model also allows a prediction of the mean life that can be expected at nonna! operating temperatures.
The usual ambients are well below the temperature levels chosen for accelerated testing. For example, a V130LAlOA
operating at 130Vac in a 55°C environment has a mean life, from figure 6(a), of about 9,152,824 hours (1045 years). Note at
the lower bias voltage an even longer mean life is expected. Although the V130LA and V68ZA type devices are specifically
described, the results are representative of other types of Harris Varistors. Additional evidence of the conservative ratings of
the Harris Varistor is the absence of systematic or repeated field failures during over fifteen years of product use.
It is noted that the mean life curves have a steep slope. This indicates a high activation energy. As operating temperature is
decreased, the mean life increases rapidly. Also, as the voltage stress is lowered, life expectancy will also increase. The
maximum stress curve represents the worst-case condition of a device at its lowest voltage limit operated at the maximum
allowable rating. In usual practice, the median of a population of devices will operate close to the 80% voltage stress curve.

FOr some applications the circuit designer requires other stability information to assess the effects of time on circuit
perfonnance. Figures 7, 8, and 9 illustrate the stability of additional Harris Varistor parameters when operated at maximum
rated voltage and 100°C for 10,000 hours (-1.15 years). The graphs indicate upper decile, median and lower decile response,
furnishing useful design information on the stability of V N, standby power drain, and the nonlinear exponent (a).

SOr-------------------------r-----,
SAMPLE SIZE n = 43

SAMPLE SIZE n = 43
DEVICE TYPE: V130LA
OPERATING UFE: V" 130VRMS AT TA .. 100°C

tI

!z45

210~~---+------~P~E~RC~E~N~TI~L~E~S-----+----~

DEVICE TYPE: V130LA
OPERATING UFE: V" 130VRMS AT TA" 100°C
a MEASURED AT: 0.1 TO 1.DmA

w

90TH

~

j'.... r-..

PERCENTILES

w 4D~-f__1F~~-;~-=90~T~H~----. .~--__+
~
z

..

50TH

:::J

~ 3S~~~:t::::==~==;;~======~~==::t

180~~

o

__

~

______

1 000 2000

~

____________-L____

4000
8000
HOURS UNDER STRESS

10TH
~

10,000

Figure 7. Voltage Stability

30""
o 1000 2000

4000
8000
HOURS UNDER STRESS

Figure 8. Nonlinear Exponent Stability

8-13

10,000

i..

5

~

1

SAMPLE SIZE n • 43
DEVICE TYPE: V130LA
OPERATING UFE: V • 130VRMS AT TA

!:

.........

!:i

g
'; 0.5

""-

=100°C

,

PERCENTILES
90TH

""-

>

50TH

!C

..:

"10TH
0.1

o

1000 2000

4000
HOURS UNDER STRESS

8000

10,000

Figure 9. Leakage Stability

DC BIAS RELIABILITY
Harris Varistors are also applied across dc power lines where transient impulses may occur. This application more frequently
uses the low voltage type of device. The varistor is designed to have high reliability when the dc bias voltage is below VN,
where the current is of the order of microamperes and little average power is dissipated. This operation is analogous to the ac
bias condition.
Varistors can operate reliably under power dissipation from intermittent transient pulses. Ratings are provided in the
specifications for this type of service. Operation is not characterized for continuous power dissipation since transient
applications generally do not require this capability. The stress under continuous power dissipation can be severe and its effects
are shown below for design guidance.

DC Bias Voltage Tests
The application of a constant dc voltage within device ratings to the Harris Varistor results in a low stress. A high degree of
stability is desired, as in the ac voltage case, as the danger of increasing power dissipation with time exists. Life tests of Harris
Varistors on constant de voltage bias at accelerated test conditions were conducted. Measurements indicate stability is at least
comparable to the results of ac voltage tests. The data is illustrated in Figure 10.
Failure criteria on this test is defined as a ±10% shift in VN . No units exceeded this failure limit during the 3000-hour accelerated test. It should be noted that the polarity of parameter readout is the same as the polarity of the stress.
SAMPLE SIZE n = 30
DEVICE TYPE: V68ZA
DC VOLTAGE UFE: V = 56Voc, TA • 125°C

75
PERCENTILES
90TH

~ 70

~
!:
~

50TH
65
10TH

60

o 168

SOO

1000
2000
HOURS UNDER STRESS

Figure 10. Accelerated DC Voltage Life

8-14

3000

DC Power Tests
Application of a constant current to the varistor results in nearly a constant power condition. In practice, a constant power life
test can be implemented easily, using a current limiting resistor and a voltage source about twice VN for significant power
levels that are above the rating. The long-term response is characterized by a continuing increase in leakage current, especially
noticeable at low voltages. This is illustrated in Figure 11. This test is at a high stress compared to the normal application
levels. The change in leakage causes VN to fall gradually with time. This is illustrated by Figures 12 and 14 showing VN vs.
time.
The response to dc power life may be put into further perspective with an analysis of a series of accelerated temperature tests.
These tests were run on low voltage products at stress temperatures of 55°C, l00"C, 125°C, and 145°C. The change in low
voltage leakage current was selected as the most sensitive indicator of degradation and was plotted against time. The device
end-of-life was defined at a leakage current limit of lOOIlA. The mean life results were found to be a good fit to the Arrhenius
model as shown in Figure 13. The self-heating caused by device power dissipation was added to the ambient temperature of
the test. This Arrhenius model can be used to predict mean life at normal operating temperatures by extrapolation. For
example, at 55°C operating ambient, a mean life of 2,400,000 hours (271 years) continuous operation is projected. This is
equivalent to a constant average failure rate of 0.42 Parts Per Million or 0.042% per 1,000 hours.
With judicious derating to a modest power level, the varistor may be used at continuous power dissipation on a dc line. These
applications are limited and highly specialized as the device is intended primarily for intennittent, transient service.
SAMPLE SIZE n. 20
DEVICE TYPE: V24ZA4 (SIMILAR TO V22ZA3)
DC POWER UFE: Po = 0.6 WATTS AT TA = 55°C

PERCENTILES

~
./

.,.

./

"-

-

,./'

--::::::

500

-----

V

-

50TH

10TH
2000

1000
1500
HOURS UNDER STRESS

0>
ZI<:::i
~iii

Figure 11. Accelerated DC Power Life, Leakage
Current Variation for Low Voltage Varistor

-

28

(

220
PERCENTILEJ

200

90TH

~

....

~

50TH

~

i'...

l!: 160

I

g

~140

........

""--

10TH
PERCENTILES

10TH

22 '--

f-~AMPLE SIZE n

150

= 20

DEVICE TYPE: V24ZA4
DC POWER UFE: Po. 0.6 WATTS AT TA = 55°C
500

1000
1500
HOURS UNDER STRESS

-

100

2000

o

I

-

I

SAMPLE SIZE n = 60
r-DEVICE TYPE: Vl30LA
DC POWER UFE: Po = 0.5 WATTS AT TA = 100°C
150

500

1000
1500
HOURS UNDER STRESS

(b) Line Voltage Varistor

(a) Low Voltage Varistor

Figure 12. Accelerated DC Power Life, VN(DC) Variation

8-15

:lw
00:

50TH

120

I
o

180

,

-<
...1<...I

90TH

2000

108

II

ARRHENIUS MODEL

I I I I

DC POWER UFE AT 0.6 WATIS
(MAXIMUM RATED POWER)

I

..
..... ..,

'

~

.. ... !""'~

~

~

..

~

DEVICE TYPE: V24ZA4 (SIMILAR TO V22ZA3)
FAILURE CRITERIA: IL ~ 0.1 mA AT 10V
~70 150 130 110100 80 80 70 60 50 40
180 160 140 120
AMBIENT TEMPERATURE IN ·C

3025

Figure 13. Reliability Model DC Power Life

PULSE ENERGY CAPABILITY
The ability of the Harris Varistor to absorb large amounts of transient energy is the key to its utility. No other suppressor device
combines equal performance with the same economic advantage. Pulse energy is absorbed throughout the bulk of the device.
The effect of pulse stress is to shift the low current end of the V-I characteristic as illustrated in Figure 14. With sufficient stress
(unipolar) the curve will become asymmetrical as shown in Figure 14(a). Other fonns of electrical or temperature stress affect
the low current region as well. The general response to most stress is a shift of the low current V-I segment to the right. That is
the main reason for the consistent use of the failure definition as a change in VN(OC) of±10%.

~



200

~

No. of Alternating Pulses

I

I
2+24

Peak Current (Amperes)

Pulse Duration (J.lS)

2+24
750

3000

1

8x20

1 8x20

I

1 I

I

J

50
750

3000

1

8x20

1 8x20

25

4500

lOx 1000

8x20

Test Temperature ("C)

25

85

25

85

With 130Y RMS Applied

Yes

Yes

No

No

Catastrophic Failures vs Sample Size

0/3

0/3

0/10

OliO

Figure 16(A). Voltage '!Ype: VI30LAI0A (14mm)

-~
Q>
z~

<:J

~

.....:I

g
:I!

~

>
No. of Alternating Pulses

225
215
205
195
185

I
I
I
I
I I
I I
2+24

2+24

Peak Current (Amperes)

3000

1

Pulse Duration (J.lS)

8x20

1 8x20

750

3000
8x20

50
750

1
1 8x20

50

6500

lOx 1000

8x20

25

85

Test Temperature ("C)

25

85

With I30Y RMS Applied

Yes

Yes

No

No

Catastrophic Failures vs Sample Size

0/3

0/3

OliO

OlIO

Figure 16(B). Voltage '!Ype: VI30LA20A (20mm)

• These test conditions simulate very closely those called for in the transient voltage suppression test and the duty cycle test of ULI449.

8-17

~iii

-<
...I<...I
;:)w
011:

The results of pulse testing on the V130LAI0A and the Vl30LA20A are shown in Figures 16(a) and 16(b). The results of
these tests on the Vl30LA series are typical of the excellent response obtained on other Harris Varistors.
The first pulse test in the series simulates very closely the conditions required in the transient voltage suppression test and the
duty cycle test of UL 1449. The second test is identical to the first except that it was conducted at 85°C instead of 25°C. This
illustrates the high temperature capability of the Harris Varistor. The ability to perform under high energy conditions is
indicated by the stability of the devices when they are subjected to repeated long duration (10 x l(X)Ollsec) pulses. The ability
to perform under high current conditions is indicated by the stability of the devices when they are subjected to peak current
waveforms up to and above rated conditions.
Data for defining energy withstand capability are presented in Figure 17 for the low voltage varistor (V68ZA types) and for the
line voltage. varistor (V130LA types). These curves show a statistical estimate of the energy to failure distribution. The
distributions are shown on normal probability paper where the estimated percentiles of failure can be obtained. The surge test
method uses a quasi-current source to apply a single surge of 8/20 energy stress after which the rated continuous voltage is
applied, l30Y RMS for line voltage units and 40V RMS for low voltage devices. The failure mode was a catastrophic
punchthrough of the ceramic body occurring after the surge stress and during application of rated voltage. Thus, the immediate
cause was thermal runaway on rated voltage, induced by overheating from surge energy absorption. A post-test readout of
nonfailed devices showed no significant degradation of V-I characteristics.
-30

-20

o

-10

10

-3200

)0-

-1 (J

o

2(J

1(J

3CJ

~ 200

CI

a:
w

Il!w

ffi150
w

ffi

Ul

...5100

-

~ 58

I- ... ""

i!!: ~o
Ul

-2a

250

20
10
0.01 0.1

1

...

-

~

~4mm

80 90

14mm

100

... """

~

po-

~

~

Lm

ill

10 20 3040 60

150

911

8U 911.99

~

.... ~

Is

7mm

is
0.01 0.1

1

10 203040 60

80 90

911

9II.8911.11S

CUMULATIVE PERCENT FAILURE

CUMULAnVEPERCENTF~LURE

(b) Line Voltage Varistor (Type VI30LA)

(a) Low Voltage Varistor (Type V68ZA)

Figure 17. Pulse Energy Capability to Single Pulse of 8 x 20lls
The distribution curves reflect the conservatism of the Harris Varistor energy ratings. For example, 7rnrn and 14rnrn line
voltage devices (Vl30LA types) are rated at 8J and 30J respectively. Figure 17 indicates a statistical estimate at these energy
levels of 1% or less of the population failing.
Pulse energy testing also has been performed at 60Hz for single cycle and ten cycle surges. This test simulates conditions
possible in ac line applications, especially in crowbar circuits and when used in conjunction with spark gaps to enhance
turnoff. In these tests the pulse energy application is immediately followed by maximum rated ac voltage. The results also are
presented on a normal probability graph as distributions of energy vs. percent failure. Figure 18 illustrates low voltage and line
voltage varistor performance.

8-18

---3- 150 P LSi~ :t.VEFOR",61 ON YCL~~-:::010""---+--I---l

. / ~'"

u..,

i

."

-20

-3
z ....

Mechanical Shock

MlI·Std·7S0
Method 2016.2

ISOO g's, O.S msec
S Pulses, XI, YI,

0/60

0/10

0/40

0/42

~iXi
-c(

c(::::i

...Jc(...J

;:)w

alI:

Zl.
Vibration

MlI·Std-7S0
Method20S6

20 g·s.lOO2000Hz Xl, VI, ZI

OISO

OlIO

OISO

0/40

Flammability

MlI-Std-202
Method lIlA

IS sec. Torching
10 sec. to Flameout

0/80

OISO

0/60

N/A

Constant
Acceleration

MlI·Std-750
Method 2006

Y2, 20,000 g'.
Min.

0/60

N/A

0/60

0140

ENVIRONMENTAL AND STORAGE RELIABILITY
The construction of the Harris Varistor ensures stable characteristics over the wide variety of environments in which electronic
equipment is operated, stored, and shipped. Testing of the Harris Varistor confirms the stability of low-voltage and line-voltage
types when subjected to accelerated high-temperature storage and humidity stresses. The 1000-hour stability life data at 125°C
storage conditions are shown in Figure 19 for two types of varistors.
An example of the electrical and environmental tests performed and typical results obtained, under Test Matrix II, are shown in
Table 5.

8-19

Table S. Electrical and Environmental Test Results on Varistor Packages
TEST
(FAILURES/SAMPLE)
PACKAGE TYPE
MILITARY
TEST

CONDITION

METHOD

RADIAL
LAIZA

INDUSTRIAL
DAJDB

LOW·PROFILE
RADIALRA

CONNECTOR
PlNCP

Operating Life

N/A

12S"C, 1000 hrs.
Bias Voltage

01200

0150

01150

01100

High-Temperature
Storage

MIl-Std·75O
Method 1032

lSO"C, 1000 brs.

0/300

0150

01120

01100

Thermal Shock

Mil-Std-75O
Method 1051

·55"C to +12S"C
5 CYcles

01200

0140

01140

0142

Humidity

N/A

85"C; 85% R.H.

01150

0150

01100

0/80

The lOoo·hour stability life during accelerated humidity testing is shown in Figure 19. Note that the low voltage varistor type
has been subjected to two tests sequentially. The normal4O"C, 95% R.H., l000-hour test was followed by the very severe 85°C,
95% R.H. test. Excellent stability is observed through this combined testing sequence.
PERCENTILES
90TH

SAMPLE SIZE n • 30
DEVICE TYPE: V68ZA
STORAGE UFE: TA • 1250C
75

210

PERCENTILES
90TH

50TH

200

~ 70

g

1

50TH

10TH

3!:
~65

180

50

o

158

SAMPLE SIZE n • 45
DEVICE TYPE: V130LA
STORAGE UFE: TA 125°C

170

10TH
500
HOURS UNDER STRESS

1000

=

o

158

(a) Low Voltage Varistors

500
HOURS UNDER STRESS

1000

(b) Line Voltage Varistors

Figure 19. Accelerated Storage Life

The lOOO-hour stability life during accelerated humidity testing is shown in Figure 20. Note that the low voltage varistor type
has been subjected to two tests sequentially. The norma140oC, 95% R.H., lOOO-hour test was followed by the very severe
85° C, 95% R.H. test. Excellent stability is obsened through this combined testing sequence.
PERCENTILES

SAMPLE SIZE n • 30
DEVICE TYPE:V58ZA

,

HUMIDITY UFE:
75 400C,1I5% RH FOR 1000HRS.

90TH

220
HUMIDITY UFE:
8SoC, IIS% RH FOR 1000HRS.

210

90TH

~ 70

50TH

50TH

g
3!:
z
> 55

,....

-

10TH
PERCENTILES

168

500

...

10TH

180
170

SAMPLE SIZE n • 55
DEVICE TYPE: V130LA
HUMIDITY UFE: 40°C, 115% R.H.
I

1000
HOURS UNDER STRESS

1000

o

158

I

500
HOURS UNDER STRESS

(a) Low Voltage Varistors

(b) Line Voltage Varistors

Figure 20. Accelerated Humidity Life

8·20

1000

QUALIFICATION PROCEDURES
New products are reliably introduced to market by the proper use of design techniques and strict adherence to process layout
ground rules. Each design is reviewed from its conception through early production to ensure compliance to minimum failure
rate standards.
New process/product qualifications have two major requirements imposed. First is a check to verify the proper use of process
methodology, design techniques, and ground rules. Second is a series of stress tests designed to accelerate failure mechanisms
and demonstrate its reliability.
From the earliest stages of a new product's life, the design phase, through layout, and in every step of the manufacturing
process, reliability is an integral part of every Harris Semiconductor product. This kind of attention to detail "from the ground
up" is the reason why our customers can expect the highest quality for any application.

RADIATION HARDNESS
For space applications, an extremely important property of a protection device is its response to imposed radiation effects.
Electron Irradiation
A Harris MOV and a silicon transient suppression diode were exposed to electron irradiation. The V-I Curves, before and after
test, are shown in Figure 21.

v

HARRISMOV
200

i'"'"-"

V
100
80

---- .

......

SIUCON TRANSIENT SUPPRESSION DIODE

~

.'.'

l

.'.'.'

.....
:

60

c>

40

zl-

c(:J

-

~iii

PRETEST

"'~"~~,, 108 RADS, 18MeV ELECTRONS

I

20

I

104

108

CURRENT (AMPERES)

Figure 21. Radiation Sensitivity of Harris V130LAI and Silicon Transient Suppression Diode
It is apparent that the Harris MOV was virtually unaffected, even at the extremely high dose of 108 rads, while the silicon

transient suppression diode showed a dramatic increase in leakage current.
Neutron Effects
A second MOV-Zener comparison was made in response to neutron fluence. The selected devices were equal in area
Figure 22 shows the clamping voltage response of the MOV and the zener to neutron irradiation to as high as 1015 N/cm2. It is
apparent that in contrast to the large change in the zener, the MOV is unaltered. At higher currents where the MOV's clamping
voltage is again unchanged, the zener device clamping voltage increases by as much as 36%.
Counterclockwise rotation of the V-I characteristics is observed in silicon devices at high neutron irradiation levels; in other
words, increasing leakage at low current levels and increasing clamping voltage at higher current levels.
The solid and open circles for a given fluence represent the high and low breakdown currents for the sample of devices tested.

8-21

-c(
...Jc(...J

::>w
00::

Note that there is a marked decrease in current (or energy) handling capability with increased neutron fluence.
Failure threshold of silicon semiconductor junctions is further reduced when high or rapidly increasing currents are applied.
Junctions develop hot spots, which enlarge until a short occurs if current is not limited or quickly removed.
The characteristic voltage current relationship of a PN-Junction is shown in Figure 23.
300

200

I

1.~K ~o~',~l~h

1111

"

VARISTOR V130A2
INITIAL AT 1015
100

I::'!

..
II

,,""

I

80

60

1.5K200
AT1012

50

IL

40

l

II

1

30
1.SK 2lw

20

10
10

J

V ..

~

lim I~n

I
10

~

1.5/200

107

1.SK200
AT 1015

~1~1
106

AMPERES

Figure 22. V-I Characteristic Response to Neutron Irradiation for MOV and Zener Diode Devices
SATURATION
CURRENT

~,ij~~~~OsiNI~IENisSHOI_D
BY RADIAL

REVERSE
BIAS

Figure 23. V-I Characteristic of PN-Junction

At low reverse voltage, the device will conduct very little current (the saturation current). At higher reverse voltage VBO (breakdown voltage), the current increases rapidly as the electrons are either pulled by the electric field (Zener effect) or knocked out
by other electrons (avalanching). A further increase in voltage causes the device to exhibit a negative resistance characteristic
leading to secondary breakdown.
This manifests itself through the formation of hotspots, and irreversible damage occurs. This failure threshold decreases under
neutron irradiation for zeners, but not for Zinc Oxide Varistors.
Gamma Radiation
Radiation damage studies were performed on type V130LA2 varistors. Emission spectra and V-I characteristics were collected
before and after irradiation with 106 rads CofIJ gamma radiation.
Both show no change, within experimental error, after irradiation.

8-22

SAFETY
The Harris Varistor may be used in systems where personnel safety or equipment hazard is involved. All components, including
this semiconductor device, have the potential of failing or degrading in ways which could impair the proper operation of such
systems. Well-known circuit techniques are available to protect against the effects of such occurrences. Examples of these
techniques include fusing and self-checking. Fault analysis of any systems where safety is in question is recommended.
Potential device reaction to various environmental factors has been discussed throughout this section. These and any other
environmental factors should be analyzed in all circuit designs.
Should the varistor be subjected to surge currents and energy levels substantially above its maximum ratings, it may physically
fail by package rupture or expUlsion of material. It is recommended that protective fusing be used as described in Chapter 4. If
not fused, the varistor should be located away from other components or be physically shielded from them.
Harris Varistors have received listing under an Underwriters Laboratories standard for "Across-The-Line Components", E56
529(N), and "Component- Transient Voltage Surge Suppressors", E75961(M).
If the system analysis indicates the need for a maximum degree of reliability, it is recommended that Harris be contacted for a
customized reliability program.
It is stressed that most Harris Varistor parameter and reliability testing requires the use of voltages of a magnitude that is
hazardous. When Harris Varistor testing is contemplated, provisions must be made to insure personnel safety.

REFERENCES
1. Erwin A. Herr, Alfred Poe and Albert Fox, "Reliability Evaluation and Prediction/or Discrete Semiconductors," EEE
Transactions on Reliability, Volume R-29 No.3, August, 1980, GE Pub. No. 300.1.
2. A.V. Fiegenbaum, Total Quality Control, New York; McGraw Hill, Third Edition, 1983.

0>

zt«:J
~iD

-«
....1-

«....I

;:)w

00:

8-23

........

9

TV

VARISTOR PRODUCTS
PAGE
VARISTOR PRODUCT DATA SHEETS
AS Series

High Energy Metal-Oxide Varistor for Arrester Applications ........................ .

9-11

Automotive AUML
Series

Multilayer Transient Surface Mount Surge Suppressors ........................... .

9-14

BAtBB Series

Industrial High Energy Metal-Oxide Varistors ................................... .

9-22

·C" III Series

Radial Lead Metal-Oxide Varistors for the TVSS Environment ...................... .

9-26

CA Series

Industrial High Energy Metal-Oxide Disc Varistors ............................... .

9-34

CH Series

Surface Mount Metal-Oxide Varistors ......................................... .

9-39

CP Series

Connector Pin Metal-Oxide Varistors .......................................... .

9-43

CS Series

Connector Pin Metal-Oxide Varistors .......................................... .

9-48

DAtDB Series

Industrial High Energy Metal-Oxide Varistors ................................... .

9-51

HA Series

Industrial High Energy Metal-Oxide Varistors ................................... .

9-55

LA Series

UL Recognized Radial Lead Metal-Oxide ...................................... .
Varistors for Line Voltage Operation

9-59

MASeries

Axial Lead Metal-Oxide Varistors ............................................. .

9-67

MLSeries

Multilayer Transient Surface Mount Surge Suppressors ........................... .

9-72

NA Series

Industrial High Energy Metal-Oxide Square Varistors ............................. .

9-80

PASeries

Base Mount Metal-Oxide Varistors ........................................... .

9-84

RA Series

Low Profile Radial Lead Metal-Oxide Varistors .................................. .

9-88

ZASeries

Radial Lead Metal-Oxide Varistors for Low-to-Medium Voltage Operation ............. .

9-95

9.1 INTRODUCTION
Harris Varistors represent the state-of-the-art in metal-oxide varistor technology, offering high energy capabilities and excellent
voltage clamping characteristics.
Harris Varistors are voltage dependent, symmetrical, metal-oxide semiconductor devices. Their characteristics enable them to protect against high transient voltage spikes (when properly selected) to meet anticipated loads. When the protected equipment or circuit encounters high voltage spikes, the varistor impedance changes from a very high standby value to a very low conducting value,
thus clamping the transient voltage to a protective level. The excess energy of the incoming high voltage pulse is absorbed by the
Harris Varistor, protecting voltage sensitive components against damage.
The protection afforded by the Harris Varistors not only guards expensive and voltage sensitive equipment from physical damage,
but also improves functional reliability in components that can encounter temporary upset due to transient voltages of lower amplitudes.
9-1

Ircn

011-0
cn::::l
-0
IrO

~If

A BROAD RANGE OF PRODUCTS TO FIT EVERY TRANSIENT VOLTAGE
SUPPRESSION NEED
Features
•
•
•
•

Wide VoltagelEnergy Range
Excellent Clamp Ratio
Fast Response TIme
Low Standby Power

•
•
•
•

•
•
•
•

ISO 9000 Approved
IEC Conformance
No Follow-On Current
DESC (QPL) Parts

UL Recognized
RadHard
CSA Recognized
CECC Approved

Special Products for Special Applications
CH Series
Surface-Mount Varistors

•
•
•
•

UL/CSA Recognized
Higher Reliability
Save on Board Real Estate
Increases Circuit Density

ZA Series

•
•
•
•

High Energy Capability
Rigid Terminals
Isolated
Low Inductance
Improved Creep and Strike
ULlCSA Recognized

•
•
•
•
•

Provides Protection in Connectors
22,20 and 16 Pin Gauge Size
RadHard
Compact Size
Solderable

RA Series

•
•
•
•
•

Low Profile
High Temperature Capability
In-Line Leads
Precise Seating Plane
UL/CSA Recognized

MA Series

• Axial Package
• Wide Voltage
• Automatic Insertion

High-Reliability Series

AUMLlML Series

• Surface Mount
• Significant Size Reduction
• High Reliability

•
•
•
•

CS/CP Series
Connector Pin Varistors

BB, BA, DA, DB, HA Series

•
•
•
•
•
•

Radial Package
Low Voltage Operation
ULlCSA Recognized
CECC Approved

"C"IIIILA Series

•
•
•
•
•

100% Prescreened
100% Process Conditioning
Meets Military Specifications
DESC (QPL) Parts
Rad Hard

• CECC

9-2

Radial Package
Line Voltage Operation
ULlCSA Recognized
CECC Approved
PA Series

•
•
•
•

Rigid Mountdown
NEMA Creep and Strike Distance
Quick Connect Terminal
UL/CSA Recognized

NA, CA Series

• Industrial Discs
• Solderable Contacts
• Edge Passivation

AS Series

• Arrester Discs

9.2 CONCEPTS OF TRANSIENT VOLTAGE PROTECTION
Varistor characteristics are measured at high current and energy levels of necessity with an impulse waveform. Shown
below is the ANSI STD C62.1 waveshape, an exponentially decaying waveform representative of lightning surges, and
the discharge of stored energy in reactive circuits. See Figures 9.1 and 9.2.
Based on industry practices, the 8120jls current wave (8jls rise and 20jls to 50% decay of peak value) is used as a
standard for current (I,m) and clamp voltage (Ve> ratings shown in the specification tables and curves. Ratings for other
waves of different decay times are shown specifically on the pulse life derating curves.
For the energy rating (W,m)' a longer duration waveform of 10/ 1000jls is used. This condition is more representative of
the high energy surges usually experienced from inductive discharge of motors and transformers. Harris
Varistors are rated for a maximum pulse energy surge that results in a varistor voltage (VN(d,) shift ofless than
±(10% + IV) of initial value.
To determine the energy absorbed in a varistor the following equation applies:
E =KVclr

where I is the peak current applied, Vc is the clamp voltage which results, r is the pulse width and K is a constant. K values
are 1.0 for a rectangular wave, 1.4 for a 1OIlOOO/ls wave and for a 8/20/ls wave.

100

90

r --------

r.~,

100V/div.
10Aldiv.
10!'S/div.

SOURCE: ANSI
STD. C62.1-1975

I
I
I

I

~~
::I~~ ~

I

50

---

---+------I
I
I

I

I

VJRTUA~ START OF WAVE

l1~

I

I

..., ~

~,

~
Peak Current Test Impulse Wave
81lS front duration 1201lS Impulse duration
except as noted.

8/20!,s Test Wave. Ip ·315V
V130LA10A

a::(J)

01-

u

Figure 9.1

Figure 9.2

I(J)::l

-0
a::

0

~~

Note that the rated energy (Wtm) and the energy absorbed in a varistor may not be identical. A specimen with lower
clamping voltage will absorb less energy. This effect tends to be greatest at rated peak current (I,m) with an 8120jls wave.
It is important to note, as demonstrated by the above equation, that poorer varistors must absorb higher energy levels
than the better performance varistors with lower clamp voltages, yet they actually provide less over-voltage protection.
For that reason, energy ratings based on an 8120jls pulse tend to overstate varistor capability. The 10/1 OOOjlS waveform
consequently gives a more realistic energy rating value.

9.3 SPEED OF RESPONSE
The measured response time of a varistor is influenced by lead configuration and length. In a typical application, the
response time is shorter than the inductive lead effect. In a coaxial configuration, one could show response times ofless
than a few nanoseconds. See Figure 3.18 page 3-12.

9-3

Table 9.2 Term Definitions

Term
DC Voltage, Vm(dc)

RMS Voltage, Vm(ac)

Definition
Maximum allowable steady state dc applied voltage, DC standby current, 10 =20/1A
typical, 200/1A maximum at TA =25 0 C, except V18ZA to V36ZA 20mm size:
ID =200~A (TYP), 3mA max and U24RA22 to V36RA22.
Maximum allowable steady state sinusoidal voltage (RMS) at 50-60Hz. If a nonsinusoidal
waveform is applied, the recurrent peak voltage should be limited to 'V2xV m(ac).

Energy, Wtm

Maximum allowable energy for a single impulse of 10/1000/1s current waveform. Energy
rating based on a VNshift of less than ± 10%.

Peak Current, 11m

Maximum allowable peak current for a single impulse of 8120/1s waveform with rated
continuous voltage applied. See pulse lifetime rating curves for other conditions.

Varistor
Voltage, VN(dc)

Varistor peak terminal voltage measured with a specified current applied. For dc conditions,
lmA is applied for a duration of 20ms to Is. For ac conditions lmA peak 60Hz wave is
applied.

Clamping
Voltage, Vc

Maximum terminal voltage measured with an applied 8120/1s impulse of a given peak
current. See V-I curves and table for product ratings of clamping voltage over the allowable
range of peak impulse current.

Capacitance

Typical values measured at a test frequency of 1.0 MHz. Maximum capacitance can be 100%
higher than the typical value measured at 1.0 MHz.

9.4 VARISTOR SAFETY PRECAUTIONS
Should the varistor be subjected to surge currents and energy levels substantially above maximum ratings, it may
physically fail by package rupture or expulsion of material. It is recommended that protective fusing be used as described
in Chapter 4. If not fused, the varistor should be located away from other components or be physically shielded from
them.
Harris Varistor encapsulant complies with flammability requirements of Underwriters Laboratories
Standard UL1414 and has a flammability rating of 94V-O.

9-4

Table 9.3 - Varistor Product Family Selection Guide

...

lo<:Z
",w_

w~:$.

A.:::>

0

MAXIMUM STEADY-STATE APPUED VOLTAGE

~

a:w~
Z

-

DlSCSIZESI
PACKAGES

w

80 500

0.5 -5.0

150 1000

0.2-25

5x8

40-100

0.07 1.7

3mm

25 - 4500

0.1 - 35

5,7,10,
14,20 (mm)

100 -6500

0.4 -160

5x8,10x16,
14x22(mm)

1,200 9000

11 - 360

7,10,14,
20 (mm)

6500

70 -250

25,000 40,000

2701,050

50,00070,000

45010,000

20,000 100,000

20010,000

1206
1210
1812
_

Table 9.4

SERIES

RA

AUML,
ML,CH,
CP,CS

BA,BB

CA,NA

AS

Operating Ambient Temperature (w/out derating)

-55 to
+125°C

-55 to
+ 125°C

-55 to
+85°C

-55 to
+85°C

-55 to
+85°C

-55 to
+85°C

-55 to
+85°C

-55 to
+85°C

-55 to
+6OoC

Storage Temperature

-55 to
+150"C

-55 to
+150"C

-55 to
+ 125°C

-55 to
+125°C

-55 to
+125°C

-55 to
+ 125°C

-55 to
+ 125°C

-55 to
+ 125°C

-55 to
+80"C

2500

NA

2500

1000

NA

5000

5000

NA

NA

HiPot Encapsulation
(Note 2)
Voltage Temperature
Coefficient (VC at
Specified Test Current)
Insulation Resistance (MQ)

LA,ZA

MA

PA
(Note 1)

DA,DB
&HA

<.OI%JOC <.OI%JOC <.OI%JOC <.OI%JOC <.OI%JOC <.OI%JOC <.OI%JOC <.OI%JOC <.Ol%JOC

>1000

NA

>1000

>1000

NOTES:
1. Base Plate Temperature.
Solderabilily: Per MIL STD 202, Method 208C.
2. Dielectric withstand per MIL STD 202, Method 301, 2500 Vdc, for 1 minute.

9-5

NA

>1000

>1000

NA

NA

a:(/)

0 ....
.... U
(/)::1

-0
a:O

~lf

3100
90

'\

~

o 80
~ 70

AUML,ML,\
'\ CP, CS, CH,
'lj.RASERIES ""-j

a:: 60

"'

\

\
50
...-1"" '\
40
IBAlBB, CA, DAlDB,
30
~
20 f - - ~ LA, HA, MA, NA, PA, ZA
\
SERljS I
10
'\
\
I
I
o A
-55 50 60 70 80 90 100 110 120 130 140 150

IL

~

r--

z

~

~

""

AMBIENT TEMPERATURE -

'C

Figure 9.3 - Current Power, Energy
Rating vs. Temperature

~

~

I-

Z

W

LEAKAGE
-REGION
.1 SAMPLE TYPE
o V130LA10A

(3

u:

u.

w

8

-.1

-.2

W

-.3

~
a:

-.4

§

W

0-

:::;;
~

-.5

L/
/
/
10.5

NORMAL
I OPERATION

~

V22ZA3

10"

10-4

10'

10'

10'

CURRENT (AMPERES)

Figure 9.4 - Typical Temperature Coefficient of Voltage Versus Current,
14mm Size, -55 to +125°C

9.5 HOW TO SELECT A HARRIS VARISTOR
To select the correct Harris Varistor for a specific application, determine the following information:

1. What is system RMS or dc voltage?
A. Phase to Ground _ _ _ _ _ __
B. Phase to Phase _ _ _ _ _ __
2. How will the Harris Varistor be connected?
A. Phase to Ground _ _ _ _ _ __
B. Phase to Phase _ _ _ _ _ __

3. Calculate required varistor voltage at 10-25% above system RMS or dc voltage.
A. VPhase to Ground X 1.1 = - - - - - - - B. VPhase to Phase x 1.1 = - - - - - - - The maximum continuous RMS or dc varistor voltage should be equal to or greater than either 3A or 3B. This
maximum continuous RMS or dc varistor voltage can be found in the rating and characteristic tables Vm(ac) or Vm(dc)"
4. Selecting the correct varistor voltage is reasonably straightforward, but selecting the proper energy rating is more
difficult and normally presents a certain degree of uncertainty. Choosing the highest energy rating available is
expedient, but usually not cost effective.
As economic considerations enter the selection process, the worst case size of the transient, the frequency of
occurrence, and the life expectancy of the equipment to be protected cannot be ignored.
ANSI/IEEE C62.41-1980 addresses these considerations, and the reprint in Chapter 1 gives the background and the
environment description of this standard. From ANSI/IEEE C62.41-1980 it becomes evident that the equipment or
component to be protected is not as important as the location in the electrical system. ANSI/IEEE C62.41-1980
divides the electrical distribution system into 3 location categories. Figure 9.5 defines these location categories in
detail.
9-6

c

A

A. Outlets and Long Branch Circuits
All outlets at more than 10m (30
ftl from Category B with wires

#14-10
All outlets at more than 20m (60
ftl from Category C with wires

#14-10
B. Major Feeders and Short Branch
Circuits
Distribution panel devices
Bus and feeder systems in
industrial plants
Heavy appliance outlets with
"short" connections to the

service entrance
Lighting systems in commercial

buildings
C. Outside and Service Entrance
Service drop from pole to
building entrance

Run between meter and
distribution panel

Overhead line to detached
buildings
Underground lines to well pumps

Figure 9.5 - Location Categories
Table 9.5 - Surge Voltages and Currents Deemed to Represent the Indoor Environment
and Recommended for Use in Designing Protective Systems
Location
Category
Center
A. Long branch
circuits and
outlets

B. Major feeders
short branch
circuits, and
load center
Notes:

Comparable
To IEC 664
Category

Impulse
Waveform

Medium Exposure
Amplitude

Type
of Specimen
or Load
Circuit

Energy (Joules)
Deposited in a Suppressor3)
With Clamping Voltage of
500V

lOOOV

(l20V System) (240V System)

II

III

6kV
200A

High impedance(l)
Low impedance(2)

1.2/50l1s
812011s

6kV
3kA

O.5l1s - 100kHz

6kV
500A

0.511S - 100kHz

-

-

0.8

1.6

High impedance(l)
Low impedance(2)

-

-

40

80

High impedance(l)
Low impedance(2)

-

-

2

4

(1) For high-impedance test specimens or load circuits, the voltage shown represents the surge voltage. In making simulation

tests, use that value for the open-circuit voltage of the test generator.
(2) For low-impedance test specimens or load circuits, the current shown represents the discharge current of the surge (not
the short-circuit current of the power system). [n making simulation tests, use that current for the short-circuit current of
the test generator.
(3) Other suppressors which have different clamping voltages would receive different energy levels.

Table 9.5 shows the open-circuit voltage and short-circuit current ofthe transients which can be expected at location
A and B.
The Harris Varistor selected must first survive the worst case transient (see "Medium Exposure
Amplitude" in Table 9.5) and, secondly, clamp the maximum open-circuit voltages to levels which will not
damage equipment or components in the system to be protected.
5. Select proper location category, A or B.
6.

Determine worst case transient current and voltage from Table 9.5.

9-7

o::~
~O

(J)::::>
-0
0::0

~g:

7. Knowing the maximum continuous RMS or dc varistor voltage (from 3), determine maximum clamping voltage
from V-I curve for the device selected using the worst case transient current found in 6.
8. Does this clamping voltage provide the required protection level? If not, repeat Step 7 using a higher energy-rated
device. If this process proves to be ineffective, consult your local Harris sales office for assistance.

9. In many cases the source of the transient is known. The transient energy can be calculated, and maximum clamping
voltage can be determined from the V-I characteristic since the maximum pulse current or source impedance is
known. Examples of these calculations can be found in chapter 4.

9.6 HOW TO CONNECT A HARRIS VARISTOR
Transient suppressors can be exposed to high currents for short durations in the nanoseconds to millisecond time frame.
Harris Varistors are connected in parallel to the load, and any voltage drop in the leads to the varistor will
reduce its effectiveness. Best results are obtained by using short leads that are close together to reduce induced
voltages and a low ohmic resistance to reduce I • R drops.

9.7 ELECTRICAL CONNECTIONS
9.7.1 Single Phase:
Line

Neutral

Gr.

This is the most complete protection one can select, but in many cases only Varistor 1 or Varistor 1 and 2 are selected.
Line

Single Phase 2 Wire 110V
Gr.

Line

Single Phase 2 Wire 240V
Gr.

Line

T

Single Phase 3 Wire 1201240V

Gr.
""""!~~"""---+---+-240V

Line

~--+----L--

9-8

1

9.7.2 3 Phase:
3 Phase 220/380V
Ungrounded

Jl

Suppressor

Connection

t

~

1-4

/;:'

2-4
3-4

3

2
1

/~
80V~

3 Phase 220V or 380V

220V

~

1-2
2-3
3-1

220V

~

3

2
_220V_

3 Phase 220V
2

1-2
2-3
1-3

1-3
1-2
2-4 } Lower

3 Phase 220V

3-4

Voltage

1-2
1-3
3-2
I-Gr.
2-Gr.
3-Gr.

3 Phase 1201208V
(4 Wire)
(If only 3 suppressor use I-Gr, 2-Gr, 3-Gr)

£C!II

011-(.)

!II:;)

-0

£Co

:o;g:
1 _41SV_ 2

1-2
1-3
3-2
I-Gr.
2-Gr.
3-Gr.

3 Phase 240/41SV
(If only 3 suppressor use I-Gr, 2-GR, 3-Gr)

3

For higher voltages use same connections, but select varistors for the appropriate voltage rating.

9-9

9,7.3 DC Applications:
DC al>plications require connection between plus and minus or plus and ground and minus and ground.

For example, if a transient towards ground exists on all 3 phases (common mode transients) only transient suppressors
connected phase to ground would absorb energy. Transient suppressors connected phase to phase would do absolutely
nothing.

Common
Mode
Transient

a) Incorrect

b) Correct

Figure 9.6 - Common Mode Transient and Correct Solution

On the other hand if a differential mode of transient (phase to phase) exists then transient suppressors connected phase
to phase would be the correct solution.

Differential
Mode
Transient

a) Incorrect

b) Correct

Figure 9.7 - Differential Mode Transient and Correct Solution

This is just a selection of some of the more important variations in connecting transient suppressors.

The logical approach is to connect the transient suppressor between the points ofthe potential difference created by the
transient. The suppressor will then equalize or reduce these potentials to lower and harmless levels.

9-10

AS Series
High Energy Metal-Oxide Varistor for Arrester
Applications

August 1993

Features
• Provided in Disc Form for Unique Packaging by Customer
• Electrode Finish Enables Pressure Contact for Stacking Application
• Available Disc Sizes: 32mm, 42mm, 52mm and 60mm Diameter
• No Follow Current
• Large Surge Current Capability
• Designed for Lightning Protection of Distribution Transformers
AS SERIES

Description

Applications

AS series arresters are designed for protection from lightning and switching surges in high-power distribution equipment.

• Arrester Discs should be stored in a moisture free
environment at all times

Discs are designed to provide high-energy handling capability and long term stability in stressful applications.

• Mechanical handling should be avoided to prevent
chipping of edges

Typical applications include porcelain. polymeric, under oil.
and metal-clad arresters.

Absolute Maximum Ratings For ratings of individual members of a series. see Device Ratings and Characteristics chart
AS SERIES

UNITS

Rated Voltage:
AC Voltage Range •..............•..•....•.....................................

3.00 to 6.00

KV

Steady State Applied Voltage:
AC Voltage (MCOV) ...•........•......•..••.........•..•.....•.•.........•...•.

2.55 to 5.10

KV

Transient:
Peak Pulse Current (lTM) for 4/10 IJS Current Wave ...............................•....
Single-Pulse Energy Rating for 2ms Current Wave ................................... .

65 to 100
2.6 to 10

KA
KJ

Operating AmbientTemperature (TA) •••••••••••••••••••••••••••••••••••••••••••••••••

60

°C

CAUTION: Copyright

© Harris Corporation 1993

File Number
9-11

2492.2

a:(/)
011-(.)
(/)::1
-0
a:O

~lf

Specifications AS Series
Device Ratings and Characteristics
MAXIMUM RATINGS (+SOOC)
CONTINUOUS

MODEL
NUMBER

CHARACTERISTICS (+2SOC)

TRANSIENT
PEAK
CURRENT
(4/1 OilS)

MAXIMUM DISCHARGE
VOLTAGE (Vc) AT TEST
CURRENT (Ip) (8I20I1s)

RMSVOLTAGE

ENERGY
(2ms)

PART SIZE

RATED
VOLTAGE

MCOV

WTU

In.

Vc

Ip

(mm)

(KV)

(KV)

(KJ)

(KA)

(KV)

(KA)

V452AS32

32

4.50

3.83

3.2

65

14.3

5

V502AS32

32

5.00

4.25

3.5

65

16.0

5

V602AS32

32

6.00

5.10

3.50

65

19.0

5

V452AS42

42

4.50

3.83

5.4

100

15.0

10

V502AS42

42

5.00

4.25

6.00

100

16.7

10

V602AS42

42

6.00

5.10

6.00

100

20.0

10

V452AS52

52

4.50

3.83

7.50

100

14.3

10

V502AS52

52

5.00

4.25

8.20

100

16.0

10

V602AS52

52

6.00

5.10

9.50

100

19.0

10

V302AS60

60

3.00

2.55

8.00

100

9.0

10

V332AS60

60

3.30

2.81

8.50

100

10.0

10

V402AS60

60

4.00

3.40

10.00

100

12.0

10

Other Electrical Ratings,

Per unit 01 Rated Voltage (TA

=600C Maximum):

System Line to Neutral Maximum..•.......................••....••.•..•.......•.....•.....•..•.....•

0.60

Maximum System Line to Une Voltage ......•....•..•......•..••...•....•....•.•.......•••....•....••

1.00

Maximum Temporary Overvoltage. duration:
1800s ......•••..•••.••.•••...•..••.•.•.....•••.••.•••.•••••••.•.•.•.•.••••.•..••••.•.••.•..•

lOs .................................................•...........•.•.•..................•..
O.ls .......................•..............................•................................
Discharge Current. 8120 J!S Wave. 20 Discharges. 50s to 60s apart:
32size............. , ........................................................................ .
42 size.....•.•......••........•••...•..............•.••.•....•.......••.•.....•.....•........
52 size.................••.............•..............................••..............•.......
60 size...•.......•..................•.•.............................•.......•................

9·12

1.05
1.15
1.25
5KA
tOKA
10KA
10120KA

AS Series
Packaging
PASSIVATION COLLAR
MIN. THICKNESS = 0.10
ELECTRODE
OF SPRAYED
ALUMINIUM
PARTICLES

FACE CAMBER
=0.15MAX

I·

L

_'I~
0.05

.

ELECTRODE

Dimensions in Millimeters
PART SIZE

DISC DIAMETER
(0 D)

VOLTAGE
FAMILY

LENGTH OF ARRESTER
(L)

AS32

31.75 ± 0.75

V302

25.40 ± 0.75

AS42

41.25 ± 0.75

V332

28.00 :! 0.75

AS52

52.50± 0.75

V402

33.75 ± 0.75

AS60

60.75±1.25

V452

39 ± 1.00

V502

43 ± 1.00

V602

43 ± 1.00

Dimensions are in millimeters.

a:(/)

011-0
(/)::1
-0
a:O

~g:

9·13

Automotive
AUML Series
Multilayer Transient
Surface Mount Surge Suppressors

August 1993

Features
• Leadless Chip form Surface Mount
• Zero Lead Inductance
• Variety of Energy Ratings Available; (1210, 1812 and 2220 Sizes)
• 125°C Continuous Operating Temperature
• Load Dump Energy Handling Capability per SAE Specification J1113
AUMLSERIES

• Low Profile, Compact Chip Size
• Inherently Bidirectional
• No Plastic or Epoxy Packaging Guarantees Better than 94V-0
Flammability Rating

Description
The Automotive multilayer (AUML) series of transient surge
suppressors was specifically designed to protect the
sensitive electronic equipment of an automobile, from
destructive transient voltages. The most common transient
conditions result either from a large energy discharge or a
steady state overvoltage. Almost all the electronic systems
in the automobile, e.g. antilock brake systems, direct ignition
systems, airbag control systems, wiper motors, etc., are
susceptible to damage from voltage transients and thus
require protection. The AUML transient suppressors have
temperature independent protection characteristics and
afford protection from -55°C to +125°C. Multilayer

suppressors are designed to fail short when overstressed
and, thus protect the associated equipment. The AUML suppressor is manufactured from semiconducting ceramics
which offer rugged protection, excellent transient energy
absorption. and increased intemal heat dissipation in an
exceedingly small package. The devices are in chip form,
eliminating lead inductance and guaranteeing the fastest
speed of response to transient surges. The AUML surge
suppressors require significantly smaller space envelopes
and land pads than traditional silicon TVS diodes or surface
mount metal oxide varistors (MOVs), thus allowing deSigners
to reduce size and weight while increasing system reliability.

Absolute Maximum Ratings For ratings of individual members of a series, see Device Ratings and Characteristics chart
AUMLSERIES

UNITS

Continuous:
Steady State Applied Voltage:
DC Voltage Range (VM(OC) ••••••••••••••••••••••••••••••••••••••••••••••••••••••

16

V

Transient:
Load Dump Energy, (WLO) ••••••••••••.••.•••••••••••••..••••••.•...•••..•...••••
Jump Start Capability (5 minutes), (VJUMP) •••••••••••••••••••••••••••••••••••••••••••

3.0 to 25
24.5

J
V

Operating AmblentTemperature Range (T.J .......................................... .

-55 to +125

°C

Storage Temperature Range (TSTG) ••••••••••••••••••••••••••••••••••••••••••••••••••

-55 to +150

°C

Temperature Coefficient (av) of Clamping Voltage (Vel at SpecHled Test Current ............. .

<0.01

'%I"C

CAUTION: These devices are sensitive to electrostatic discharge. Users should follow proper I.C. Handling Procedures.
Copyright © Harris Corporation 1993

9-14

File Number

3387.1

Specifications AUML Series
Device Ratings and Characteristics
MAXIMUM RATINGS (125°C)

CHARACTERISTICS (25°C)
NOMINAL VARISTOR
VOLTAGE
AT 10mA DC TEST
CURRENT

JUMP
LOAD
MAXIMUM
CONTINUOUS
START
DUMP
DC
VOLTAGE
ENERGY
(5 MIN)
VOLTAGE
(10 PULSES)

MAXIMUM
STANDBY
LEAKAGE
(AT 13V DC)

MAXIMUM CLAMPING
VOLTAGE (Vel
AT TEST CURRENT
(8/20~s)

VM(DC)

VJUMP

W LD

VN(DC) MIN

VN(DC) MAX

IL

Vc

Ip

(V)

(V)

(J)

(V)

(V)

(~A)

(V)

(A)

V18AUMLA1210

16

24.5

3

23

32

50

40

1.5

V18AUMLA1812

16

24.5

6

23

32

100

40

5

V18AUMLA2220

16

24.5

25

23

32

200

40

40

MODEL
NUMBER

NOTES:
1. Average power dissipation of transients not to exceed 0.15, 0.3 and 1 watt for model sizes 1210, 1812 and 2220 respectively.
2. Load dump energy rating (into the suppressor) of a voltage transient with a time constant of 115 milliseconds to 230 milliseconds.
3. Thermal shock capability per Mil-Std-750, Method 1051: -55°C to +1250 C, 5 minutes at 25°C, 25 Cycles: 15 minutes at each extreme.
4. For application specific requirements, please contact Harris sales office.

Power Dissipation Requirements

.A

Transients in a suppressor may generate heat too quickly for
it to be transferred to the surroundings during the pulse interval. Continuous power diSSipation capability, therefore is not
a necessary requirement for a suppressor, unless transients
occur in rapid succession. Under this condition, the average
power dissipation required is simply the energy (watt-seconds) per pulse times the number of pulses per second. The
power so developed must be within the specifications shown
on the Device Ratings and Characteristics table for the specific device. Furthermore, the operating values need to be
derated at high temperatures as shown in Figure 1.

w

100

:::>

gO

~
0
w

80

..J

!C
a:

"-

...0z

w
0
a:
w

...

\

70
60

,
\

,

\

SO

40
30
20

\

10~+-~~--+-~-+--~+--+~~\~
O~~~~~__~~~~~~~'
-55

50

60

70

80

90 100 110 120 130 140 150

AMBIENT TEMPERATURE <"C)

FIGURE 1. CURRENT, ENERGY AND POWER DERATING
CURVE

w

:3

~

100 ........................ .
90 .................... .

~
w

..."o

SO •••••••••••• :,.

!Zw
o

a:

...w

.!

fl·_·-

10 ...

01""';'

0 1 = VIRTUAL ORIGIN OF WAVE
EXAMPLE:
T = TIME FROM 10% TO 90% OF PEAK FOR AN 8120~s CURRENT

r-- T~

I

-Tl~

=

=

Tl VIRTUAL FRONT TIME 1.25 x t
T2 = VIRTUAL TIME TO HALF VALUE
(IMPULSE DURATION)

I

nME

-T2---..;
FIGURE 2. PEAK PULSE CURRENT WAVEFORM

9-15

WAVEFORM:
8~. Tl VIRTUAL FRONT
TIME
20~s T 2 VIRTUAL TIME TO
HALF VALUE

= =
= =

0::1/)

011-0
1/)::1
-0
0::0

~!f

AUMLSeries
Maximum V-I Characteristic Curve
100
- - MAXIMUM CLAMPING VOLTAGE -

- - MAXIMUM LEAKAGE -

1210=
181~=
2220

w

~

!:i

g

1210~
10

=1812
=2220

""'"
10~

"'"

100~

"'"

lmA

"""
10mA

""

100mA
CURRENT

""'"lA

"'"''
lOA

"'"

100A

FIGURE 3. WORST CASE LEAKAGE CURRENT/CLAMPING VOLTAGE CURVE FOR AUML SERIES

Soldering Recommendations
The principal techniques used for the soldering of
components in surface mount technology are Infra Red (IR)
Reflow, Vapour Phase Rellow and Wave Soldering. When
wave soldering, the AUML suppressor is attached to the
substrate by means of an adhesive. The assembly is then
placed on a conveyor and run through the soldering process.
With IR and Vapour Phase rellow the device is placed in a
solder paste on the substrate. As the solder paste is heated
it rellows, and solders the unit to the board.
With the AUML suppressor, the recommended solder is a

6213612 (Sn/Pb/Ag) silver solder paste. While this configuration is best, a 60/40 (Sn/Pb) or a 63137 (SnlPb) solder paste
can also be used. In soldering applications, the AUML suppressor is held at elevated temperatures for a relatively long
period of time, with the wave soldering operation the most
strenuous of the processes. To avoid the possibility of generating stresses due to thermal shock, a preheat stage in the
soldering process is recommended, and the peak temperature of the solder process should be rigidly controlled.

dient steeper than 4 degrees per second; the ideal gradient
being 2 degrees per second. During the soldering process,
preheating to within 100 degrees of the solders peak temperature is essential to minimize thermal shock. Examples of
the soldering conditions for the AUML series of suppressors
are given in the table below.
Once the soldering process has been completed, it is still
necessary to ensure that any further thermal shocks are
avoided. One possible cause of thermal shock is hot printed
circuit boards being removed from the solder process and
subjected to cleaning solvents at room temperature. The
boards must be allowed to cool to less than 50 degree Celsius before cleaning.

When using a reflow process, care should be taken to
ensure that the AUML chip is not subjected to a thermal gra-

9-16

SOLDERING
OPERATION

TIME
(SECONDS)

PEAK
TEMPERATURE (OC)

IR Reflow

5 -10

220

Vapour Phase Reflow

5 - 10

222

3·5

260

Wave Solder

AUML Series
Recommended Pad Outline

Packaging

I
1
B

1
T
D

1-01..o__---- A - - - -.....~I

NOTE: Avoid metal runs in this area.
CHIP SIZE

CHIP SIZE
1210
SYMBOL

IN

1812
MM

IN

1210

2220
MM

IN

1812

2220

MM

SYMBOL

IN

MM

IN

MM

IN

MM

0.070

1.80

0.07

1.8

0.118

3.00

A

0.219

5.51

0.272

6.91

0.315

8.00

DMAX

B

0.147

3.73

0.172

4.36

0.240

6.19

E

0.02
±0.01

0.50
±0.25

0.02
±0.01

0.5
±0.25

0.03
±0.01

0.75
±0.25

C

0.073

1.85

0.073

1.85

0.073

1.85

L

0.125
±0.012

3.20
±D.30

0.18
±0.014

4.5
±0.35

0.225
±0.016

5.7
±0.4

W

0.10
±0.012

2.54
±0.30

0.125
±0.012

3.2
±0.30

0.197
±0.016

5
±0.4

Soldering Recommendations
Material - 62136/2 Sn/Pb/Ag or equivalent
Temperature - 230°C, 5 seconds max
Flux - Non activated

Load Dump Energy Capability
A Load dump transient occurs when the alternator load in
the automobile is abruptly reduced. The worst case scenario
of this transient occurs when the battery is disconnected
while operating at full rated load. There are a number of different load dump specifications in existence in the automotive industry, with the most common one being that
recommended by the society of automotive engineers, specification #SAE J 1113. Because of the diversity of these load
dump specifications Harris defines the load dump energy

capability of the AUML suppressor range as that energy dissipated by the device itself, independent of the test circuit
setup. The resultant load dump energy handling capability
serves as an excellent figure of merit for the AUML suppressor.
Standard load dump specifications require a device capability of 10 pulses at rated energy, across a temperature range
of -40°C to + 125°C. This capability requirement is well
within the ratings of all of the AUML series (Figure 4).

a: I/)
01-

1-°
1/);:)
-0

a:O

~g:

V(10mA)

35.----------------------,
1210=3J
25 ~~~~~~~~~~~~~~~~~~~f22~2~0~=i2~[j
~

1~2=~

w20r---------------------~

~

g~ 15r---------------------~
10r---------------------~
5r---------------------~

o

2

3

4

5

6

7

g

10

11

12

# OF LOAD DUMPS

FIGURE 4. AUML LOAD DUMP PULSING OVER A TEMPERATURE RANGE OF -SSoC TO +12SoC

9-17

AUML Series
Further testing on the AUML series has concentrated on
extending the number of load dump pulses, at rated energy,
which are applied to the devices. The reliability information
thus generated gives an indication of the inherent capability
of these devices. To date the 1210 series of device has been

subjected to over 2000 pulses at its rated energy of 3 joules;
the 1812 series have been pulsed over 1000 times at 6
joules and 2220 series has been pulsed at its rated energy
of 25 joules over 300 times. In all cases there has been little
or no change in the device characteristics (Figure 5).

V(10mA)
35
2220 =25J

1812=6J

30

1210=3J

25
w

~ 20

!:i
§!

15
10
5

o

o

I

~

50

100

150

200

250
300
1# OF LOAD DUMPS

1,000

350

~

2,000

FIGURE 5. REPETITIVE LOAD DUMP PULSING AT RATED ENERGY

The very high energy absorption capability of the AUML
suppressor is achieved by means of a new, highly controlled
manufacturing process. This new technology ensures that a
large volume of suppressor material, with an interdigitated
layer construction, is available for energy absorption in an
extremely small package. Unlike equivalent rated silicon
TVS diodes, all of the AUML device package is available to

act as an effective, uniform heat sink. Hence, the peak temperatures generated by the load dump transient are significantly lower and evenly dissipated throughout the complete
device (Figure 6). This even energy dissipation ensures that
there are lower peak temperatures generated at the P-N
grain boundaries of the AUML suppressor.

FIRED CERAMIC

METAL
ELECTRODES

DEPLETION
REGION
DEPLETION
REGION

1~....jj....jj-l+-!.fo...jj.-!I!l)'i1
T
-1 ~~~~~~~IT)!:1
t
'"""""--.......
~..,

FIGURE 6. INTERDIGITATED CONSTRUCTION OF AUML SUPPRESSOR

9-18

AUML Series
There are a number of different size devices available in the
AUML series, each one with a load dump energy rating,
which is size dependent.
Experience has shown that while the effects of a load dump
transient is of real concern, its frequency of occurrence is
much less than those of low energy inductive spikes. Such

low energy inductive spikes may be generated as a result of
motors switching on and off, from ESD occurrences, fuse
blowing, etc. It is essential that the suppression technology
selected also has the capability to suppress such transients.
Testing on the V18AUMLA2220 has shown that after being
subjected to a repetitive energy pulse of 2 joules, over 6000
times, no characteristic changes have occurred (Figure 7.)

100 V AT lOrnA

Vl BAUMLA2220

10
1000

2000

3000
4000
SOOO
NUMBER OF PULSES

6000

7000

FIGURE 7. REPETITIVE ENERGY TESTING OF THE V18AUMlA2220 AT AN ENERGY lEVEL OF 2 JOULES

Temperature Effects
In the leakage region of the AUML suppressor, the device
characteristics approaches a linear (ohmic) relationship and
shows a temperature dependent affect. In this region the
suppressor is in a high resistance mode (approaching 109
ohms) and appears as a near open-circuit. Leakage currents
at maximum rated voltage are in the microamp range. With

clamping transients at higher currents (at and above the ten
milliamp range), the AUML suppressor approaches a 1-100
characteristic. In this region the characteristics of the AUML
are virtually temperature independent. Figure 8 shows the
typical effect of temperature on the V-I characteristics of the
AUML suppressor.

100

~

-400C~

0:1J)

011-0
1J):::l
-0

1--t-2SoC

0:0

f--+BSoCf f

~g:

/

+12S0C.[
lilA

lOIlA lOOIlA lmA lOrnA 100mA lA
CURRENT

lOA

100A 1000A

FIGURE 8. TYPICAL V-I CHARACTERISTICS OF THE V18AUMLA2220 at -40°C, +2SoC, +8SoC AND +12SoC

Speed of Response
The clamping action of the AUML suppressor depends on a
conduction mechanism similar to that of other semiconductor devices (i.e. P-N Junctions). The apparent slow response
time often associated with transient voltage suppressors
(Zeners, MOVs) is often due to parasitic inductance in the
package and leads of the device and is independent of the
basic material (silicon, zinc oxide). Thus, the single most critical element affecting the response time of any suppressor is

its lead length and, hence, the inductance in the leads. The
AUML suppressor is a pure surface mount device, with no
leads or external packaging, and thus, it has virtually zero
inductance. The actual response time of a AUML surge suppressor is in the 1 to 5 nanosecond range and this response
time is more than sufficient for the transients which are likely
to be encountered in an automotive environment.

9-19

AUML· Series
Tape and Reel Specifications
• Conforms to EIA • 481, Revision A
• Can be Supplied to IEC Publication 286 • 3
TAPE

SmmWIDE
TAPE

12mm WIDE TAPE

Chip Size

1210

1812

2220

Quantity Per
178mmReel

2000

1000

1000

Quantity Per
330mmReei

8000

4000

4000

TAPE WIDTH
SYMBOL

Smm

DESCRIPTION

I

12mm

Dependent on Chip Size to Minimize Rotation.

Ao

Width of Cavity

Bo

Length of Cavity

Dependent on Chip Size to Minimize Rotation.

Ko

Depth of Cavity

Dependent on Chip Size to Minimize Rotation.

W

Width of Tape

F

Distance Between Drive Hole Centers and Cavity Centers

E

Distance Between Drive Hole Centers and Tape Edge

S±0.2

P1

Distance Between Cavity Center

P2

Axial Distance Between Drive Hole Centers and Cavity Centers

Po

Axial Distance Between Drive Hole Centers

Do

Drive Hole Diameter

3.5± 0.5

I
I

12 ± 0.2
5.4±0.5

1.75±0.1
4±0.1

I

8±0.1

2 ±0.1
8±0.1
1.55 ± 0.05

01

Diameter of Cavity Piercing

1.05 ± 0.05

11

Embossed Tape Thickness

0.3 max

I:i

Top Tape Thickness

I
I

1.55 ± 0.05
0.4 max

0.1 max

NOTE: Dimensions in millimeters.

Standard Packaging
Tape and reel is the standard packaging method of the
AUML series. The standard 330 millimeter (13 inch) reel utilized contains 4000 pieces for the 2220 and 1812 chips. and
8000 pieces for the 1210 chip. To order add "T23" to the
standard part number. eg.V18AUMLA2220T23.

Special Packaging
Option 1: 178 millimeter (7 inch) reels containing 1000
(2220.1812) or 2000 (1210). pieces are available.
To order add "H23" to the standard part number.
e.g. V18AUMLA2220H23.
Option 2: For small sample quantities (less than 100 pieces)
the units are shipped bulk pack. To order add
"A23" to the standard part number. e.g.
V18AUMLA2220A23.

9-20

178MM
OR 330MM
DIA. REEL

AUML Series
Part Nomenclature

Load Dump Energy Rating (WLO)

The part numbering system of the AUML surge suppressor
series gives the following information:

This is the actual energy the part can dissipate under load
dump conditions.
Maximum Clamping Voltage (V d

e.g. Part Number: V18AUMLA2220T23

This is the peak voltage appearing across the suppressor
when measured at conditions of specified pulse current and
specified waveform (8/20/ls). It is important to note that the
peak current and peak voltage may not necessarily be coincidental in time.

where:

v = Harris Transient Voltage Suppressor
18 = Recognized Automotive Suppressor
Rating
AUML = Automotive Series
A = Load Dump Energy Indicator
2220 (or 1812 or 1210) = Device Size
T23 (or H23 or A23) = Quantity Designator

Leakage Current (Ill
In the non-conducting mode, the device is at a very high
impedance (approaching 1090) and appears as an almost
open circuit in the system. The leakage current drawn at this
level is very low «SO/lA at ambient temperature) and, unlike
the zener diode, the multilayer TVS has the added advantage that, when operated up to its maximum temperature, its
leakage current will not increase above SOO/lA.

Description of AUML Ratings and
Characteristics
Maximum Continuous DC Working Voltage (VM(oC)
This is the maximum continuous DC voltage which may be
applied, up to the maximum operating temperature
(+12S°C), to the ML suppressor. This voltage is used as the
reference test point for leakage current and is always less
than the breakdown voltage of the device.

Nominal Voltage (VN(OC)
This is the voltage at which the AUML enters its conduction
state and begins to suppress transients. In the automotive
environment this voltage is defined at the 10 milliamp point
and has a minimum (VN(DC) MIN) and maximum (VN(DC) MAX)
voltage specified.

a:

I!!

~o

(/):::1

-0

a:O

~g:

9-21

HARRIS
SEMICONDUCTOR

SAiSS Series
Industrial High Energy Metal-Oxide Varistors

August 1993

Features
• Recognized as "Transient Voltage Surge Suppressors", UL File
#E75961 to Std. 1449
• High Energy Absorption Capability W TM
BA Series •••••••••••••••••••••••••••••••••••••••••••• 3200J
BB Series ••••••••••••••••••••••••••••••••••••••••••• 10,OOOJ
• Wide Operating Voltage Range VM(AC)RMS
BA Series •••••••••••••••••••••••••••••••••••••• 130V to 880V
BB Series •••••••.•••••••••••••••••••••••••••• 11 OOV to 2800V
• Rigid Terminals for Secure Wire Contact
• Case Design
SubAssembly
BB SERIES

BASERIES

Provides Complete

Electrical

Isolation of Disc

• Large Diameter Disc ••••••••••••••••••••••••••••••••••• 60mm

Description
SA and BS series transient surge suppressors are heavyduty industrial metal-oxide varistors designed to provide
surge protection for motor controls and power supplies used
in oil-drilling. mining, and transportation equipment. Possible
voltage surges in their ac power supplies could cause product failure and the subsequent faulty operation of these systems.

These UL-recognized varistors have similar package construction but differ in size, ratings and electrical characteristics.
Both the SA and SB series feature improved creep and
strike capability to minimize breakdown along the package
surface, a package design that provides complete electrical
isolation of the disc subassembly, and rigid terminals to
insure secure wire contacts.

Absolute Maximum Ratings For ratings of individual members 01 a series, see Device Ratings and Characteristics chart
BA SERIES

BBSERIES

UNITS

130 to 880
175 to 1150

1100 to 2800
1400 to 3500

V
V

Transient:
Peak Pulse Current (lTM)
For 8120115 Current Wave (See Figure 2) ..............................
Single Pulse Energy Range
For 10/1 OOOI1S Current Wave (WTM)' .................................

50,000 to 70,000

70,000

A

450 to 3200

3800 to 10,000

J

Operating AmbientTemperature Range (T.J .............................

-55 to +85

-55 to +85

°C

Storage Temperature Range (TSTG)' ...................................

-55 to +125

-55 to +125

°C

Temperature Coefficient (exV) of Clamping Voltage (Vel at Specified
Test Current ....................................................

Continuous:
Steady State Applied Voltage:
AC Voltage Range (VM(AC)RMS)' .....................................
DC Voltage Range (V M(DC» ........................................

<0.01

<0.01

%JOC

Hi-Pot Encapsulation (Isolation Voltage Capability) ........................
(Dielectric must withstand indicated de voltage for one minute per MIL-STD
202, Method 301)

5000

5000

V

Insulation Resistance .•.................................•...........

1000

1000

MO

Copyright © Harris Corporation 1993

File Number
9-22

2183.2

Specifications BAiBB Series
Device Ratings and Characteristics
Series BA and BB Varistors are listed under UL file #E75961 as a UL recognized component.
CHARACTERISTICS (+25°C)

MAXIMUM RATINGS (+85°C)
CONTINUOUS

MODEL
NUMBER
VI 31 BA60

TRANSIENT

MAX CLAMPING
VOLTVcAT
200A CURRENT
(812011 5 )

RMS
VOLT·
AGE

DC
VOLT·
AGE

ENERGY
(101
1000115)

PEAK CUR·
RENT (81
20115)

VM(AC)

VM(DC)

WTM

(J)

(V)

VN(DC)
(V)

MAX

(V)

'TM
(A)

MIN

(V)

(V)

Vc
(V)

130

175

450

50000

184

200

228

340

20000

VARISTOR VOLTAGE AT 1mA
DC TEST CURRENT

TYPICAL
CAPAC/TANCE

f

=lMHz
(pF)

V151BA60

150

200

530

50000

212

240

268

400

16000

V251BA60

250

330

880

50000

354

390

429

620

10000

V271BA60

275

369

950

50000

389

430

473

680

9000

V321BA60

320

420

1100

50000

462

510

539

760

7500

V421BA60

420

560

1500

70000

610

680

748

1060

6000

V481BA60

480

640

1600

70000

670

750

825

1160

5500

V511BA80

510

675

1800

70000

735

820

910

1300

5000

V571BA60

575

730

2100

70000

805

910

1000

1420

4500

V661BA60

660

850

2300

70000

940

1050

1160

1640

4000

V751BA60

750

970

2600

70000

1080

1200

1320

1880

3500

V881BA60

880

1150

3200

70000

1290

1500

1650

2340

2700

Vl12BB60

1100

1400

3800

70000

1620

1800

2060

2940

2200

V142BB60

1400

1750

5000

70000

2020

2200

2550

3600

1800

V172BB60

1700

2150

6000

70000

2500

2700

3030

4300

1500

V202BB60

2000

2500

7500

70000

2970

3300

3630

5200

1200

V242BB60

2400

3000

8600

70000

3510

3900

4290

6200

1000

V282BB60

2800

3500

10000

70000

4230

4700

5170

7400

800

NOTE: Average power diSSipation of tranSients not to exceed 2.5W. See Figures 3 and 4 for more Information on power dlsslpaUon.

Power Dissipation Requirements
Transients in a suppressor generate heat too quickly for it to
be transferred to the surroundings during the pulse interval.
Continuous power dissipation capability, therefore, is not a
necessary design requirement for a suppressor, unless tran·
sients occur in rapid succession. Under this condition, the
average power dissipation required is simply the energy
(watt·seconds) per pulse times the number of pulses per
second. The power so developed must be within the specifi·
cations shown on the Device Ratings and Characteristics
table for the specific device. Furthermore, the operating val·
ues need to be derated at high temperatures as shown in
Figure 1. Because varistors can only dissipate a relatively
small amount of average power they are, therefore, not suit·
able for repetitive applications that involve substantial
amounts of average power dissipation.

w

100

" _\.

3

90
~ 80
fil 70

~

:5
!z

60

\.

50
40

~

~ 30

...w

\.

20
10

o

·55

50

60

0 , = Virtual Origin of Wave
T = Time From 10% to 90% of Peak
T1 = Virtual Front TIme = 1.25 • t

90

...~
~

T2

50

= Virtual TIme to Half Value (Impulse Duration)

Example: For an 8120(.15 Current Waveform:
81lS = T 1 = Virtual Front TIme
20115 T2 Virtual Time to Half Value

!zw
Ii!w

= =

...

01

"

70 80 90 100 110 120 130 140 150
AMBIENT TEMPERATURE (OC)
FIGURE 1. CURRENT, ENERGY AND POWER DERATING
CURVE

w 100 •••••••••••••
<>3

a:(J)
0 ....
....
0
(J):;)
-0
a:o

TIME

FIGURE 2. PEAK PULSE CURRENT TEST WAVEFORM

9·23

~g:

BAiBS Series
~P~~~LE~E~~~~1WJ': ;:~i~gIEN~•••••'

I

=

1.0
O.S

:i:<

-

I

a:w

~CI 0.4

~§

z>

0.5

""..

0", 0.2

~~

-MR

=

0.1

!Ii ... O.OS

,I

1,000 HOURS, TA = +S50C

MAX AT TA = +S50C

0.6

2l~
0:

"

.......

.'

.. .'

.'

'

'-

""""''''

.'.'
.......'.'

TYPATTA= +250C

...

§00.06

r

0.04

o

I

SO
90
100
110
PERCENTAGE OF MAXIMUM RATED RMS VOLTAGE (%)

FIGURE3. STANDBY POWER DISSIPATION vs APPLIED RMS
VOLTAGE AT VARIED TEMPERATURES

"

o

10
100
1,000
TIME AT RATED RMS VOLTAGE (HOURS)

FIGURE 4. TYPICAL STABILITY OF STANDBY POWER DISSIPATION AT RATED RMS VOLTAGE vs TIME

Transient V-I Characteristics Curves
6,000
5,000
4,000

MAX CLAMPING VOLTAGE
DISC SIZE 60mm
130 TO S80VM(AC~ RATING
TA = -55°C TO +8 °C

~3,000

~ 2,000

g

~ 1,000
388
700

::E
::>
;:E
~
::E

-

111111111
V881BA60V751BA60
V661BA60
VS71BA60

V,V4818A60
/ V4218A60

~

:--

I-

I':t

~

~

~

i--'.:

'" S,OOO
0( 7,000
~ 6,000

F-

"'"

1111111

100

V282BB60

~
~

4,000 V202BB60

I-"

V172BB60
3,000 VI42BB60
VI12BB60

Vl~:~~~
10-1

I-"

~10,000

§! 9,000

~ 5,000 V242BB60

300 VI51BA60

20~0_2

MAX CLAMPING VOLTAGE
DISC SIZE 60mm
1100 TO 2S00VMJA~b RATING
TA =-550C TO + 5

20,000

~

~

i.I.

600 V321BA60
V271BA60
500 V251BA60
400

30,000

·1111111

It V5118A60

101
102
103
PEAK AMPERES (A)

104

11111

2,00~0_2

10S

FIGURE 5. CLAMPING VOLTAGE FOR V131BA60· V881BA60

10.1

100

102
101
PEAK AMPERES (A)

103

104

10s

FIGURE 6. CLAMPING VOLTAGE FOR V112BB60· V282BB60

Pulse Rating Curves
50,000
20,000
10,000

g

5,000

ffi

2,000

100,000

RN
r-,!O

B

500

1i!

200



50,000

2

~

'""'-

~

_10,000 ~
~ 5,000 ~02

...z

r-....

k.105
~

.......

r--.

~

w
a: 2,000
a: 1,000
i.l04
::>
(.)
w 500 05
CI
a:
200
::>

I II III
100

 90
..J

~

SO

0

~
II:
II.

0

'\.

70

60

\.
\.

SO

~

z 40

w

(J

30

W

:e
~
:e

10.2

10.1

100
101
102
PEAK AMPERES (AI

10'

H-ttHtlH-tttt

V175LA20C
V150LA20C /
VI40LA20C'

v

V

1 1 1 1IIIilliliiITil

100~~WL-U~~Lllllim-Lllll~~Will~~WL-ULWW

10-3

~

100~~WL~UlliL..J~~-U~~Lll~~~w-~ww

104

FIGURE 3. MAXIMUM CLAMPING VOLTAGE FOR V130LA10C
TO V300LA20C

9·28

1~

1~

1~

1~
1~
PEAK AMPERES (AI

FIGURE 4. MAXIMUM CLAMPING VOLTAGE FOR V130LA20C
TO V200LA40C

"C" III Series
Pulse Rating Curves
""'''

111111111111111111

I """"
I" """ I""
V300LA40CX745

"""=

10,000

"''''

MODEL SIZE 20mm
TA -55°C TO +85O C
130 TO 300VM(AC) RATING

=

g
I-

V275LA40CX680 \
V250LA40CX620
V230LA40CX570
I 'I

Z

w

1,000

a:
a:

1-104

0

r--

W

a:
:;)

~

V175LA20CX42S
V150LA20CX360 : /
VI40LA20CX340
100
10-3

100

...'"'cw"
w

=

14mm
TA _55°C TO +8SoC
130 TO 300VM(AC) RATING

=

-

,

"""- .......

...

::::::...

FINDEFINITE

(/)

/
/

:: MODEL SIZE

/2=

_10 2
1=103

:;)

CI

1

rIO

I-

SURGE

-....;

I- CAPABILITY

;:::::::::

10

!cc
a:

1I~~30~~~fX3~~I~

10.2

10.1

100
10'
102
PEAK AMPERES (A)

100
1,000
SURGE IMPULSE DURATION (1'8)

FIGURE 5. REPETITIVE SURGE CAPABILITY FOR
V130LA20CX325 TO V300LACX745

FIGURE 6. REPETITIVE SURGE CAPABILITY FOR V130LAl OC
TO V300LA20C

10,000

g

/2

10

·,0"

!z

~ 1,000 -1'

a:

.......

~
~

(/)

100

~ INDEFINITE

~

~

MODEL SIZE = 20mm
TA _55°C TO +85 0 C
130 TO 300VM(AC) RATING

=

--

""'-

~

SURGE
CAPABILITY

...
w

fij

§

~

1=:1

B

10,000

~

10

!cc
a:
1

10

100
1,000
SURGE IMPULSE DURATION (1'5)

10,000

FIGURE 7. REPETITIVE SURGE CAPABILITY FOR V130LA20C TO V300LA40C

0:1/)

011-0
1/);:)
-0

0:0

~g:

9-29

"e" 11/ Series
Tape and Reel Data

Tape and Reel Specification

• Conforms to ANSI and EIA Specifications
• Can be supplied to IC publication 286-2
• Radial devices on tape and reel are supplied with crimped
leads, straight leads, or under-crimped leads.
Shipping Quantity
QUANTITY PER REEL

DEVICE
SIZE
CRIMPeD LeADS

"Lr'

"T" REEL

"S" REEL

"U" REEL

14mm

500

500

500

20mm

500

500

500

Tape and Reel Ordering Information

I

j'

• Crimped leads are standard on LA types supplied in tape
and reel and are denoted by the model letter "T'. Also, in
tape and reel, model letter "S" denotes straight leads and
letter "U" denotes special under-crimped leads.

f

Example:

o/>D,
STANDARD
MODEL
V130LA2OC

CRIMPED
LEADS

STRAIGHT
LEADS

UNDER
CRIMP
LEADS

V130LT20C

V130LS20C

V130LU20C

Packaging

UNDER-CRIIolPED
LEADS "LU"

o/>D,

MODEL SIZE
SYMBOL

DESCRIPTION

14mm

I

P

Pitch 01 Component
Feed Hole Pitch

12.7 ± 0.2

P,

Feed Hole Center to Pitch

2.60 ± 0.7

P2

Hole Center to Component
Center

6.35 ± 1.0

F

Lead to Lead Distance

7.50± 0.8

W

Component Alignment
Tape Width

\lIN

20mm

Po

h

25.4
(1.00)

)f'

25.4± 1.0

VARISTOR MODEL SIZE
14mm

2.00 Max
18.25± 0.75

I

Wo

Hold Down Tape Width

W,

Hole Position

W2

Hold Down Tape Position

0.5 Max

H

Height From Tape Center
To Component Base

19.0 ± 1.0

Ho

Seating Plane Height

16.0 ± 0.5

H,

Component Height

6.00 ±
0.3

12.0 ±
0.3

9.125 ± 0.625

40Max

I

46.5
Max

Do

Feed Hole Diameter

4.0± 0.2

t

Total Tape Thickness

0.7± 0.2

L

Length of Clipped Lead

12.0 Max

p

Component Alignment

3° Max

20mm

SYMBOL

MIN

MAX

MIN

MAX

A

13.5
(0.531)

20
(0.787)

17.5
(0.689)

26.5
(1.043)

0D

13.5
(0.531)

17
(0.669)

17.5
(0.689)

23
(0.906)

e

6.5
(0.256)

8.5
(0.335)

6.5
(0.256)

8.5
(0.335)

el

1.5
(0.059)

3.5
(0.138)

1.5
(0.059)

3.5
(0.138)

E

-

5.6
(0.220)

-

5.6
(0.220)

0b

0.76
(0.030)

0.86
(0.034)

0.76
(0.030)

0.86
(0.034)

..

DimenSIons are In mIllimeters (Inches)
NOTE: 10mm lead spacing also available. See ordering information.

9-30

"e" 111 Series
Available Lead Style

The Origins of Surge Overvoltages

Radial lead types can be supplied with a preformed crimp in
the leads. This is available in both 14mm and 20mm model
sizes. The lead trim option (LTR1M ) is supplied to the dimensions shown below.

There are a wide variety of transient overvoltage environments, each with radically different levels of exposure. Transients may be caused by lightning, which can inject very high
currents into the electrical system, or by switching transients.
Lightning strikes usually occur to the primary transmission
lines with resulting coupling to the secondary line through
mutual inductive or capacitive coupling. Even a lightning hit
that misses the primary AC line can induce substantial voltage onto the primary conductors, triggering lightning arresters and thus creating transients.

VARISTOR MODEL SIZE
14mm

20mm

SYMBOL

MIN

MAX

MIN

MAX

A

-

24.5
(0.96)

-

31
(1.22)

LTRIM

2.41
(0.095)

4.69
(0.185)

2.41
(0.095)

4.69
(0.185)

..

Switching transients, while of a lower magnitude than lightning, occur more frequently and thus are of a greater threat
to the AC system. Switching transients may result from fuse
blowing, capacitor bank switching, fault clearing or grid
switching.

NOTE: Dimensions are In millimeters (Inches)

'seating
Plane

G

T
\.1

Field studies and laboratory investigation of residential and
industrial low power AC voltage systems have shown that
the amplitude of a transient is proportional to the rate of its
occurrence, I.e. lower magnitude transients occur most
often. Governing bodies, in particular IEC, UL, IEEE and
ANSI have established guidelines on the transient environment one may expect to encounter in a low voltage AC
power system. Table 1 reflects the surge voltages and currents deemed to represent the indoor environment.

.1

TLtrim
Crimped and Trimmed Lead

'Seating plan interpretation per IEC-717

Ordering Information

LOCATION CATEGORY

TRANSIENT WAVEFORM!
MAGNITUDE

• To order crimped and trimmed lead styles, the standard
radial type model number "LA" is changed to the model
number "LC".

A

Long Branch Circuits
and Outlets

0.5115
100kHz

6kV
200A

Example:

B

Major Feeders and
Short Branch Circuits

1.2150115
8I2011s

6kV
3kA

0.5115
100kHz

6kV
500A

STANDARD MODEL

ORDER AS

V130LA2OC

Vl30LC20C

o::CI)

• For 10 ± 1mm lead spacing on 20mm units only; append
standard model numbers by adding "X10".

011-0

Example:

-0
0::0

CI):::I

~g:

STANDARD MODEL

ORDER AS

V130LA2OC

V130LA20CX10

• For crimped leads without trimming and other variations to
the above, please contact Harris Semiconductor Power
Marketing

9-31

"C" III Series

"c" III MOV Series
The new "C" III series of Harris radial MOVs represent the
third generation of improvements in device performance and
characteristics. The technology effolt involved in the development of this new series concentrated on extending the
existing performance and capability of the Harris second
generation of metal oxide varistors.
The characteristics of greatest importance .for a metal oxide
varistor in an AC surge environment are the peak current,
energy handling, repetitive surge and temporary over-voltage capabilities. The focus of the design effort was on
improving these characteristics and therefore offering the
maximum protection presently available to the end user.
The new "C" III series are designed to survive the harsh
environments of the AC low-power indoor environment. Their
much improved surge withstand capability is well in excess
of the transients expected in the AC mains environment. Further design rules for the development of the "C" III series
included considerations of the expected steady state operating conditions and the repetitive surge environment.
Investigation of the AC low-power indoor environment show
that most transients occur where the power enters the building and at major feeders and short branch circuits. Surges
recorded at this service entrance, location Category B from
C62.41-1992, may be both oscillatory and unidirectional in
nature. The typical "lightning surge" has been established as
a 1.2150l1s voltage wave and a 8/20l1s current wave. A short
circuit current of 3000A and open circuit voltage 6000V are
the expected worst case transients at this location.

TEST
Surge
Current

REFERENCE
STANDARD

TEST
CONDITIONS

TEST
RESULTS

The further into the facility one goes, the lower the magnitude of the transients encountered. ANSI/IEEE C62.41 differentiates between the service entrance and the interior of a
facility. Per this specification, the internal location or long
branch circuits and outlets are classified as Location Category A. The transients encountered here have oscillatory
waveshapes with frequency ranges from 5kHz to 500kHz;
with 100kHz deemed most common. Transients of the magnitude of 500A are expected in this location.

Reliability Performance of "c" III Series
The electrical ratings of the "C" III series of MOVs are conservatively stated. Samples of these devices have been
tested under additional stresses, over and above those
called out in the datasheet. The results of this testing show
an enhanced device performance.
The series of stress tests to which the units were subjected
are a combination of electrical, environmental and mechanical tests. A summary of the reliability tests performed on the
"C" III series are described in Table 2

AC Bias Reliability
The "C" III series of metal oxide varistors was designed for
use on the ac line. The varistor is connected across the ac
line and is biased with a constant amplitude sinusoidal voltage. It should be noted that the definition of failure is a shift
in the nominal varistor voltage (V N) exceeding ± 10%.
Although this type of varistor is still functioning normally after
this magnitude of shift, devices at the lower extremities of VN
tolerance will begin to dissipate more power.

UL 1449
IEEElANSI
C62.41

9000A
(8/2Ol.ls)
1 Pulse

01165

IEC 1051

7000A
(8/201.15)
2 Pulses

0/105

3000A
(8I20J.lS)
20 Pulses

0175

750A
(8/201.15 )
120 Pulses

0/65

Transient Surge Current/Energy
Capability
The transient surge rating serves as an excellent figure of
merit for the "Cn III suppressor. This inherent surge handling
capability is one of the new "C" III suppressor's best features. The enhanced surge absorption capability results from
improved process uniformity and enhanced construction.
The homogeneity of the raw material powder and improved
control over the sintering and assembly processes are contributing factors to this improvement.

Surge
Energy

UL 1449
IEEE/ANSI
C62.41
IEC 1051

90J
(2ms)
1 Pulse

01125

Operating
Life

Mil-Std-202
Method 2040

125°C, 1000
Hours, Rated
Bias Voltage

0/180

Temporary
Overvoltage

NlA

120% Maximum Rated
Varistor Voltage For 5 minutes

0170

Because of this possibility, an extensive series of statistically
designed tests were performed to determine the reliability of .
the "C n III type of varistor under ac bias combined with high
levels of temperature stress. To date, this test has generated
over 50,000 device hours of operation at a temperature of
+125 0 C, although only rated at +85 0 C. Changes in the nominal varistor voltage, measured at lmA, of less than 2% have
been recorded (Figure 8).

In the low power AC mains environment, industry governing
bodies (UL, IEC, NEMA and IEEE) all suggest that the worst
case surge occurrence will be 3kA. Such a transient event
may occur up to five times over the equipment life time
(approximately 10 years). While the occurrences of five 3

9-32

"e" 11/ Series
kiloamps transients is the required capability, the conservatively rated, repetitive surge current for the "C" III series is 20
pulses for the 20mm units and 10 pulses for the 14mm
series.
As a measure of the inherent device capability, samples of
the 20mm V130LA20C devices were subjected to a worst
case repetitive transient surges test. After 100 pulses, each
of 3kA, there was negligible change in the device characteristics. Changes in the clamping voltage, measured at 100
amps, of less than 3% were recorded (Figure 9). Samples of
the 14mm Series V175LA20C were subjected to repetitive
surge occurrences of 750A. Again, there was negligible
changes in any of the device characteristics after 250 pulses
(Figure 10). In both cases the inherent device capability is
far in excess of the expected worst case scenario.

300
V130LA20C
~ 250
.0;

E

200

~

!<

:IE

;

150
100
o

100 200

300

400 500 600 700
TIME (HOURS)

800

900 1000 1100

FIGURE 8. HIGH TEMPERATURE OPERATING LIFE 125°C
FOR 1000 HOURS AT RATED BIAS

Terms and Descriptions

..,::Ii 500

Rated AC Voltage (VM(AC)RMS)

!<

V130LA20C
3kA (8120~s)

w450

This is the maximum continuous sinusoidal voltage which
may be applied to the MOV. This voltage may be applied at
any temperature up to the maximum operating temperature
of +85 0 C.
Maximum Non-Repetitive Surge Current (lTM)

CJ

~

S! 400
CJ

z

5: 35 0

~

u

This is the maximum peak current which may be applied for
an 8/20l1s impulse, with rated line voltage also applied, without causing device failure. (See Figure 2)

(RATED FOR 20 SURGES)
30 0

o

20

30

40 50 60 70 80
NUMBER OF SURGES

90 100 110 120

FIGURE 9. TYPICAL REPETITIVE SURGE CURRENT CAPABILITY OF "C" III SERIES MOVs

Maximum Non-Repetitive Surge Energy (WTM)
This is the maximum rated transient energy which may be
dissipated for a single current pulse at a specified impulse
and duration (2ms), with the rated rms voltage applied, without causing device failure.

!<

Nominal Voltage (VN(DC»

w
~ 500

This is the voltage at which the device changes from the off
state to the on state and enters its conduction mode of operation. This voltage is characterized at the 1mA pOint and has
specified minimum and maximum voltage levels.

10

~ 600
~

V175LA20C
750A (8120~s)

550

g450

~ 400
5:
~ 350

(RATED FOR 80 SURGES)

Clamping Voltage (Ve)

u 300

This is the peak voltage appearing across the MOV when
measured at conditions of specified pulse current amplitude
and specified waveform (8/20I1s)

FIGURE 10. TYPICAL REPETITIVE SURGE CURRENT CAPABILITY OF "C" III SERIES MOVs

9-33

o

50

100
150
200
NUMBER OF SURGES

250

300

a:(/)
011-0
(/);:)
-0
a:O

~g:

CA Series

HARRIS
SEMICONDUCTOR

Industrial High Energy Metal-Oxide
Disc Varistors

August 1993

Features
• Provided Un packaged For Unique Packaging By Customer
• Solderable Electrode Finish Also Provides Pressure Contacts for
Stacking Applications
• Available Disc Sizes .......... . 32mm, 40mm, and 60mm Diameter
• Wide Operating Voltage Range

VM(AC)RMS ••••••••••

• Wide Peak Pulse Current Range 'TM
CA SERIES

• Very High Energy Capability WTM

•••••••••.•

130V to 2800V

20,OOOA to 70,OOOA

..•..•....••••••

200J to 10,OOOJ

Description
CA series transient surge suppressors are industrial high·
energy disc varistors intended lor special applications requiring un ique contact or packaging considerations. The elec·
trode linish 01 these devices is solderable and can also be
used as pressure contacts lor stacking applications.
These CA series industrial disc varistors are available in

three diameter sizes: 32, 40, and 60mm, with disc thicknesses ranging from 1.Bmm minimum to 32mm maximum.
They offer a wide voltage range of from 130 to 2BOO
VM(AC)RMS.

For information on mounting considerations refer to Applications Brief AB·BB20.

Absolute Maximum Ratings For ratings 01 individual members 01 a series, see Device Ratings and Characteristics chart
CA SERIES

UNITS

130 to 2800
175 to 3500

V
V

Transient:
Peak Pulse Current (I TM )
For 8120j.ls Current Wave (See Figure 2) ..••••••••.....•..••.•.•......••.•......•..•
Single Pulse Energy Range
For 1011000j.lS Current Wave (WTM ) .•....•..•.....•..•......••..........•...•.....•

20,000 to 70,000

A

200 to 10,000

J

Operating Ambient Temperature Range (TA) •.••••••••.•..•••••••.•...•.•••••....••.••.

·55 to +85

°C

Storage Temperature Range (TsrG)' .••..••...•••..•....•....•..•..............•.•...

·55 to +125

°C

Temperature Coefficient (aV) of Clamping Voltage (Vel at Specified Test Current. •.•.........•

<0.01

%I"C

Continuous:
Steady State Applied Voltage:
AC Voltage Range (VM(AC)RMS) •....•..........................................•.•.
DC Voltage Range (VM(DC» .•..•....•......•.•.•....•.....•......•....•..•......•

Copyright © Harris Corporation t 993

File Number
9·34

2187.2

Specifications CA Series
Device Ratings and Characteristics
MAXIMUM RATINGS (+85°C)
CONTINUOUS

CHARACTERISTICS (+25°C)

TRANSIENT

RMS
VOLTAGE

DC
VOLTAGE

ENERGY

(101
1000115)

PEAK
CURRENT
(8120115)

VARISTOR VOLTAGE AT
1mA DC TEST CURRENT

MAX
CLAMPING
VOLTV c
AT200A
CURRENT
(8120115)

TYPICAL
CAPACITANCE

f = 1MHz

MODEL
NUMBER

SIZE

VMfAC)

VMfDC)

WTM

V NfDC)

MAX

Vc

(V)

(V)

(J)

ITM
(A)

MIN

(mm)

(V)

(V)

(V)

(V)

(pF)

V131CA32
V131CA40

32
40

130

175

200
270

20000
30000

184

200

228

350
345

4700
10000

V151CA32
V151CA40

32
40

150

200

220
300

20000
30000

212

240

268

410
405

4000
8000

V251CA32
V251CA40
V251CA60

32
40
60

250

330

330
370
880

20000
30000
50000

354

390

429

680
650
620

2500
5000
10000

V271CA32
V271CA40
V271CA60

32
40
60

275

369

360
400
950

20000
30000
50000

389

430

473

750
730
680

2200
4500
9000

V321CA32
V321CA40
V321CA60

32
40
60

320

420

390
460
1100

20000
30000

462

510

539

850
830
760

V421CA32
V421CA40
V421CA60

32
40
60

420

V481CA32
V481CA40
V481CA60

32
40
60

480

V511CA32
V511CA40
V511CA60

32
40
60

510

V571 CA32
V571CA40
V571CA60

32
40
60

575

V661 CA32
V661CA40
V661CA60

32
40
60

660

850

V751CA32
V751CA40
V751CA60

32
40
60

750

V881CA60

60

V112CA60
V142CA60
V172CA60
V202CA60
V242CA60
V282CA60

60
60
60
60
60
60

560

640

400

600
1500
450
650
1600

675

50000
25000

610

680

748

1200

40000

1130

70000

1060
1300

25000

40000
70000
25000

670

750

825

1240
1160

910

5500
1200

550
770

25000
40000

2100

70000

600
900
2300

25000
40000
70000

940

1050

1160

1820
1720
1640

1000
2000
4000

970

700
1050
2600

25000
40000
70000

1080

1200

1320

2050
2000
1880

800
1800
3500

880

1150

3200

70000

1290

1500

1650

2340

2700

1100
1400
1700
2000
2400
2800

1400
1750
2150
2500
3000
3500

3200
5000
6000
7500
8600
10000

70000
70000
70000
70000
70000
70000

1620
2020
2500
2970
3510
4230

1800
2200
2700
3300
3900
4700

2060
2550
3030
3630
4290
5170

2940
3600
4300
5200
6200
7400

2200
1800
1500
1200
1000
800

910

1000

1440
1350
1300

1300
2700

40000
70000

805

820

3000
6000

500
700
1800

730

735

1900

3800
7500
1500

1600
1480
1420

2500
5000

1100
2200
4500

NOTE: Average power dissipation of transients not exceed 1.5W, 2.0W and 2.5W for model 32mm, 40mm and 60mm, respectively.

Power Dissipation Requirements
Transients in a suppressor generate heat too quickly for it to
be transferred to the surroundings during the pulse interval.
Continuous power dissipation capability, therefore, is not a
necessary deSign requirement for a suppressor, unless transients occur in rapid succession. Under this condition, the
average power dissipation required is simply the energy
(watt-seconds) per pulse times the number of pulses per
second. The power so developed must be within the specifi-

cations shown on the Device Ratings and Characteristics
table for the specific device. Furthermore, the operating values need to be derated at high temperatures as shown in
Figure 1. Because varistors can only dissipate a relatively
small amount of average power they are, therefore, not suitable for repetitive applications that involve substantial
amounts of average power dissipation.

9-35

a:

I/)

01-

I- U
1/)::1

-0

a:O

~lE

CA Series
w 100 ------------

3
~

~

...w

100

w

"~

c
w
1;(

80
70

a:

II..

50

0

z~

40

0

30

...

20

w

a:
w

" \.

90

60

15
~
~

01

I\,
\.

\.

10
50

60

Time From 10% to 90% of Peak

=Virtual Front Time =1.25 • t
=Virtual Time to Half Value (Impulse Duration)

\.

-55

TIME

=Virtual Origin 01 Wave

01
T=
T1
T2

1\

o

50

~
w

Example: For an Bl20j.lS Current Waveform:
81ls T 1 Virtual Front Time
20j.lS = T 2 = Virtual Time to Half Value

70 80
90 100 110 120 130 140 150
AMBIENT TEMPERATURE (OC)

= =

FIGURE 1. CURRENT, ENERGY AND POWER DERATING
CURVE

FIGURE 2.

PEAK PULSE CURRENT TEST WAVEFORM

Transient V-I Characteristics Curves
6,000
5,000
6,000
5,000
4,000

MAXIMUM ClAMPING WLTAGE
DISC SIZE 32mm
130 10 750 VM("") RATING
TA • "ss°C to +85°C

3,000

4,000

4,000
€3,O00

~ 2,000
:.:
~ 1,000
...

:!

900
800
700
600

:!

400

:!
"

~ 500

10"

WIIIIII

V881CA60V751CA60_

10"
10'
102
PEAK AMPERES

10'

10'

i-"

V.

~

I--

V571CA60=

10"

10"

10'
102
PEAK AMPERES

10'

10'

10'

FIGURE 4. CLAMPING VOLTAGE FORV131CA40· V751CA40

30,000

VjV481CA60
/V421CA60

V\J,~~r
:',,:,,;;

200
10"

10'

J 11111111 1111
II V511CA60

V661CA6~_

20,000

MAX CLAMPING VOLTAGE
DISC SIZE 60mm
1100 TO 2800VMJA~bRATING
TA =_550 C TO + 5

€

~

1310,000
~ 9,000
'" 8,000
.. 7,000
~ 6,000

~

~

V321CA~_

V271CA6~::

V251CA60

200
10.2

~

V151CMO
300

MAX CLAMPING VOLTAGE
DISC SIZE 60mm
250 TO 880VM(AC~ RATING
TA = -55°C TO +8 °c

300

~

~

'/

V2519~\r

FIGURE 3. CLAMPING VOLTAGE FOR V131CA32· C751CA32

6,000
5,000

o

V321CA40
V271C

rmw
10-3

:..-

i;V751CMO
V661CMO
V571CA40

V

~}~,~~

200
10-3

V.

"'"''

~

V321CA32
V271CA32
V251CA32
300

,

V511 CMO,\
V481CMO
V421CMO

~

r-

TA• ..ss°C to +&soc

130 10 750 VM("") RATING

3,000

~

1111111
V751CA32
V661CA32
V571CA32
V511CA32
V481CA32
V421CA32

MAXIMUM ClAMPING VOLTAGE
DISC SlZE 40mm

V282CA60
5,000 V242CA60
4,000 V2Q2CA60
~

VI72CA60
3,000 VI42CA60
Y112CA60

111111'"

J 1I11Il1
10.1

"""III

100

102
101
103
PEAK AMPERES (A)

104

105

FIGURE 5. CLAMPING VOLTAGE FOR V251CASO· V881CASO

100

101
102
PEAK AMPERES (A)

103

FIGURE S. CLAMPING VOLTAGE FOR Vl12CASO· V282CASO

9-36

CA Series
Pulse Rating Curves
50.000~El+H1m:==+=I=+:j:l:ri>iSCsiZe32.;;;-::-o-l
IDISC SIZE 32mm
20.000 ~-++++t1H--+--+-+-1H+ V131 CA32 - V321 CA32

50.000
20.000

10,000r~2~11~1~1~/f05~11~!!11
f....l0

~

5.000r.....

/10

10.000

6

~

!z 2.000~

::>

w
~

. 111
.

a:

~ 100~r-...~r-!!1...L~]$'1111~1!
20H~DTFm~
10
20

100

::>

1.000
IMPULSE DURATION (1'8)

50.000

20

10.000

2
10

!E::> 1.000
o

500

~

200

w

::>
UI

-"

......

"

INFE,Ajl,Tt,

-I'-100

go

~ t::::-

a:

ii:

5.000 ~02

~
z 2.000
w
I-

......

~

a: 1.000
a:
1;;;..104

::>
0

w
~

500

a:

200

UI

100

::>

~

.......

50
20

I-INDEFIN ITE

I II II
100

r--..

....... .......
............ )'.,.r....

100
50

.....

IZ

::>
0

-....

-

1.000
IMPULSE DURATION (1'8)

w

500

a:

200

~

........

......
~"

FIGURE 11. SURGE CURRENT RATING CURVES FOR
V251CA60 - V321CA60

-

100

"
-r-.-

~~

-

~ .:::- .....

1.000
IMPULSE DURATION (1'8)

r10.000

a:cn

::>
UI

DISC SIZE 60mm
V421 CA60 • V282C A60
2

20.000
10.000 ~
5.000 t"J,02

w
a: 2.000
a: 1.000

......

...............

If

er. . .

~

100.000
~1
50.000

r--..

r-

DISC SIZE 40mm
V421 CA40 • V751 CA40

FIGURE 10. SURGE CURRENT RATING CURVES FOR
V421CA40 - V751CA40

~

-

k 105

.......

103

10 20

DISC SIZE 60mm
V251CA60 - V321C A60

,..-2

N,.O
10.000

10.000

10'
105

102

II

" r-10.000

50.000
20.000

I II

20 INDEANITE

FIGURE 9. SURGE CURRENT RATING CURVES FOR
V131 CA40 - V321 CA40

R$.1

....... ~t---

1.000
IMPULSE DURATION (1'8)

500

~ 200

r-.::r-..

1.000
IMPULSE DURATION (1'8)

-

~

2

~1.000

............. ......

50

10 20

1~

1- 2•000

.......... :---.,r--

100 ~

20

~

~
z

¥ ..

~

~

I"-t--.

100

20.000
5.000

110

10 6

~

"")I.

IN?EII~ITf I

50.000

10.000

~ 5.000

ffi 2.000 ~
103

.

105

t'....

FIGURE 8. SURGE CURRENT RATING CURVES FOR
V421CA32 - V751CA32

DISC SIZE 40mm
V131 CA40 • V321 CA40

10.000 N

r-"

10
20

FIGURE 7. SURGE CURRENT RATING CURVES FOR
V131 CA32 - V321 CA32

20.000 ~

100
50

UI

~-...;:~

_"

"""

500 ~04
200

0

200~~~~Hr~.d+~~~,,~~~~~~~~~~
.......

~

z 2.000
w
a:
a: 1.000 ~

..........

50

I

5.000 ;oo..l.O

I-

~~ 1.000~10~3!ijl~
~lu::~'7IIII~!!I'1
500~04
~

~

DISC SIZE 32mm
V421CA32 - V751CA32

2

100

K

~05

........

.......

~

50
20

II

1020

10.000

INDEFINITE

r-.

,

.......

---

100
1.000
IMPULSE DURATION (1'8)

........

'::::-1'-10.000

FIGURE 12. SURGE CURRENT RATING CURVES FOR
V421 CA60 - V282CA60

NOTE: If pulse ratings are exceeded. a shift of VN(DC) (at specified current) of more than ±10% could result. This type of shift. which normally
results in a decrease of VN(DC)' may result in the device not meeting the original published specifications. but does not prevent the device from
continuing to function. and to provide ample protection.

9-37

I-(J

cn:::l
-0
a:O

~g:

~

~O4

01-

CA Series

Packaging
' \ Passivation collar

NOMINAL
SIZE
32
40
60

Electrode

DISC DIAMETER
MILLIMETERS
MIN.
MAX.
31.0
33.0
38.0
40.0
58.0
62.0

Electrode
I

-I
RMS
VOLTS
VMlac;J

130+
150+
250
275
320
420
480
510
575
660
750
880·
1100·
1400·
1700·
2000·
2400·
2800·

32mm DISC THICKNESS
MILLIMETERS
INCHES
MIN.
MAX.
MIN.
MAX.
1.8
0.071
0.094
2.4
2.1
2.8
0.083
0.110
1.6
2.2
0.063
0.087
1.8
0.071
0.098
2.5
2.1
2.9
0.083
0.114
2.9
3.9
0.114
0.154
3.1
4.3
0.122
0.169
3.5
4.7
0.138
0.185
3.8
5.1
0.150
0.201
4.4
6.0
0.236
0.173
8.11
5.1
0.240
0.327

-

-

-

--

-

--

40 AND 60mm DISC THICKNESS
INCHES
MILLIMETERS
MAX.
MIN.
MAX.
MIN.
0;134
2.5
3.4
0.098
0.150
3.8
0.110
2.8
0.079
0.106
2.7
2.0
0.118
3.0
0.087
2.2
0.138
3.5
0.102
2.6
4.7
0.138
0.185
3.5
0.150
0.205
5.2
3.8
0.165
0.224
4.2
5.7
0.181
0.248
6.3
4.6
0.209
0.283
5.3
7.2
0.240
0.327
8.1
8.3
0.287
0.406
7.3
10.3
0.512
0.362
9.2
13.0
0.453
0.630
11.5
16.0
0.551
0.748
14.0
19.0
0.669
0.886
17.0
22.5
27.0
0.787
1.063
20.0
1.260
24.0
32.0
0.945

• Avallabl. In 60mm .Iz.· only.
+ Avallabl. In 32 and 40mm only.
Nola: Perls aveilable with soldered tabs. to customer specifIC requirements or slandard design.

9·38

-

INCHES
MIN.
MAX.
1.220
1.299
1.575
1.496
2.283
2.441

CH Series

HARRIS
SEMICONDUCTOR

Surface Mount Metal-Oxide Varistors

August 1993

Features
• Recognized as "Transient Voltage Surge Suppressors", UL File
#E75961 to Std. 1449
• Recognized as "Protectors for Data Communication and Fire Alarm
Circuits", UL File #E135010 to Std. 4976
• Surface Mount Chip Intended for Hybrid-Circuit Applications
• Voltage Ratings VM(AC)RMS ••••••••••••••••••••••••• 10V to 275V
• Available in Tape and Reel for Use With Automatic Pick and Place
Equipment

CHSERIES

!O

• Compatible with Most Surface-Mounting Assembly Equipment and
Techniques

Description
CH series transient surge suppressors are small, very compact metal·oxide varistors. They are intended for use in
hybrid circuit applications in commercial and industrial
equipment utilizing direct surface-mounting techniques.

the size and weight and increase the reliability of their equipment designs.
CH series varistors are available in a voltage range from 10
to 275V VM(AC)R~S' and energy ratings up to 23J.

These devices, which have significantly lower profiles than
traditional radial-lead varistors, permit designers to reduce

Absolute Maximum Ratings For ratings of individual members of a series, see Device Ratings and Characteristics chart
CH SERIES
Continuous:
Steady State Applied Voltage:
AC Voltage Range (V M(AC)RMS) ••••••••••••••••••••••••••••••••••••••••••••••••••••
DC Voltage Range (V M(DC») ••••••••••••••••••••••••••••••••••••••••••••••••••••••

UNITS
V
V

10 to 275
14 to 369

a:~
~o

00::::1

Transient:
Peak Pulse Current (I TM )
For 81201'5 Current Wave (See Figure 2) ........................................... .
Single Pulse Energy Range
For 1011 000i.lS Current Wave (WTM ) ••••••••••••••••••••••••••••••••••••••••••••••••

250 to 500
0.8 to 23

J

Operating Ambient Temperature Range (TA)

•••••••••••••••••••••••••••••••••••••••••••

·5510 +125

°C

Storage Temperature Range (TSTG) ••.•.••••••.••.••••..•.•.•..••..••••••••....•.••••

·5510 +150

°C

<0.01

%f'C

Temperature Coefficient ((XV) of Clamping Voltage

(Vel at Specified Test Current ............. .

Copyright © Harris Corporation 1993

-0

File Number
9-39

a:O
~g:

A

2186.2

Specifications CH Series
Device Ratings and Characteristics
V82 - V240 CH Varistors are listed under Ul file #E75961 as a recognized component.
Series CH Varistors are listed under Ul file #E135010 as a recognized component.
CHARACTERISTICS (+25°C)

MAXIMUM RATINGS (+125°C)
CONTINUOUS

TRANSIENT
MAX CLAMPING
VOLTVcATTEST
CURRENT (8120IlS)

TYPICAL
CAPACITANCE

RMS
VOLTAGE

DC
VOLTAGE

ENERGY

VM(AC)

VM(DC)

WTM

ITM

MIN

VN(DC)

MAX

Vc

Ip

(V)

(V)

(J)

(A)

(V)

(V)

(V)

(V)

(A)

(pF)

V18CH8

10

14

0.80

250

14.4

18.0

21.6

42

5

2000

V22CH8

14

18
(Note 3)

10.0
(Note 2)

250

18.7

22.0

26.0

47

5

1600

V27CH8

17

22

1.0

250

23.0

27.0

31.1

57

5

1300

V33CH8

20

26

1.2

250

29.5

33.0

36.5

68

5

1100

V39CH8

25

31

1.5

250

35.0

39.0

43.0

79

5

900

V47CH8

30

38

1.8

250

42.0

47.0

52.0

92

5

800

V56CH8

35

45

2.3

250

50.0

56.0

62.0

107

5

700

V68CH8

40

56

3.0

250

61.0

68.0

75.0

127

5

600

V82CH8

50

66

4.0

500

74.0

82.0

91.0

135

10

500

Vl00CH8

60

81

5.0

500

90.0

100.0

110.0

165

10

400

V120CH8

75

102

6.0

500

108.0

120.0

132.0

200

10

300

MODEL
NUMBER

(101
1000115)

PEAK
CURRENT
(8120IlS)

VARISTOR VOLTAGE AT 1rnA
DC TEST CURRENT

f = lMHz

V150CH8

95

127

8.0

500

135.0

150.0

165.0

250

10

250

V180CH8

115

153

10.0

500

162.0

180.0

198.0

295

10

200

V200CH8

130

175

11.0

500

184.0

200.0

228.0

340

10

180

V22OCH8

140

180

12.0

500

198.0

220.0

242.0

360

10

160

V240CH8

150

200

13.0

500

212.0

240.0

268.0

395

10

150

V360CH8

230

300

20.0

500

324.0

360.0

396.0

595

10

100

V390CH8

250

330

21.0

500

354.0

390.0

429.0

650

10

90

V430CH8

275

369

23.0

500

389.0

430.0

473.0

710

10

80

NOTES:
1. Power dissipation of transients not to exceed 0.25 watt.
2. Energy rating for impulse duration of 30 milliseconds minimum to one half of peak current value.
3. Also rated to withstand 24 volts for 5 minutes.

Power Dissipation Requirements

"

Transients in a suppressor generate heat too quickly for it to
be transferred to the surroundings during the pulse interval.
Continuous power dissipation capability, therefore, is not a
necessary design requirement for a suppressor, unless transients occur in rapid succession. Under this condition, the
average power dissipation required is simply the energy
(watt-seconds) per pulse times the number 01 pulses per
second. The power so developed must be within the specifications shown on the Device Ratings and Characteristics
table for the specific device. Furthermore, the operating values need to be derated at high temperatures as shown in
Figure 1. Because varistors can only dissipate a relatively
small amount of average power they are, therefore, not suitable for repetitive applications that involve substantial
amounts of average power dissipation.

9-40

100

\

w
:::> 90
80

1\

..J

~

\

0

w 70
!:c 60

...0a:

...z
w

\

50

\

40

\.

0

a: 30
w
20

'"

\.

10

o "
-55 50

\
60

70 80 90 100 110 120 130 140 150
AMBIENT TEMPERATURE (OC)

FIGURE 1. CURRENT, ENERGY AND POWER DERATING
CURVE

CH Series
w
3100

~

0 1 =Virtual Origin of Wave

~

T = Time From 10% to 90% of Peak
Tl Virtual Front Time 1.25 .t
T2 Virtual Time to Half Value (Impulse Duration)

W
D.

...o
~

=
=

so

=

Example: For an 8120I1S Current Waveform:
81lS = T 1 = Virtual Front Time
201lS = T 2 = Virtual Time to Half Value

tJ

II:

w

D.

TIME

FIGURE 2.

PEAK PULSE CURRENT TEST WAVEFORM

Transient V-I Characteristics Curves
500
400
300

~200

-

C) RATING
TA = -Ssoc T +12SoC
V430CH8

3,000

103

FIGURE 3. CLAMPING VOLTAGE FOR V18CH8 - V68CH8

10.1

i-"
~

i-"

100
101
102
PEAK AMPERES (A)

103

10.

FIGURE 4. CLAMPING VOLTAGE FOR V82CH8 - V430CH8

Pulse Rating Curves
SOO

2,000
MODEL SIZE S x Smm
V18CHS - V6SCH8

~
200
100

g

...z

w 20
II:
II:

::l

10

w

S

U

CI

~r--

I

:.J..!l3
.......

.......

---

2

INDEFINITE

0.2
20

500

~

106 -

200 No:

w

100

II:
II:

::l

r-,!O

-

v V

.....

-

CI

20

-::::-

:=:::::::: t;:: ~t-

::l
< ......

"'"

INDEFINITE

I I 1111
0.5
20

g

...

100

106

~
~t---

'"w

()

CI

a:

0.2

1,000
IMPULSE DURATION (ILS)

IMPULSE DURATION (ILS)

FIGURE 12. SURGE CURRENT RATING CURVES FOR
V130CP16 - V150CP16

1,000
500
200

g

100
50
f--

102

zw

........

a:
a:

~ 20~~~~~~~~~~~~~~~~-+-+-+++++H
~

8
~

10~~~-~1'-~~~~~~~~~1f~~~;~~'~~~

'"

()

INDEFINITE

5

a:

2

'"

100

1,000
IMPULSE DURATION (lLs)

2

~
-..;-

1~03 4
1010~06
"7

~

-.......;;; ~

INDEFINITE

P"~

V:><. k": K.

r--.

.0;;::1:::

~

:-...... .....

0.5

~;:::::~

0.5~~_ _~_
20

MODEL SIZE 20 GAUGE
V130CP20 - V150CP20

-...!



10

LU

5

a:
en

2

....
Z
a:
a:
0

CI

:>

:..t.03

...

:---- ..c

INDEFINITE

0.5
0.2
20

II

/

...

100

1,000
500

MODEL SIZE 22 GAUGE
V8CP22 - V38CP22

2 10

r--

I

200
~ 100
.... 50

104
:::::--).0~06

z

LU

a: 20
a:

~

-

r-_

:>

10

LU

5

a:
en

2

0

CI

:-

:>

~ ::::::

MODEL SIZE 20 GAUGE
V130CP22 - V150CP22

..J..

-.,l .....
10

........

......

.......
;: INDEFINITE

0.5

1-+-,+-,H-,

1,000
IMPULSE DURATION (I's)

FIGURE 15. SURGE CURRENT RATING CURVES FOR
VSCP22 - V3SCP22

I--t-t-+++tttt----+-_+~_+""

0.2
ftt1
0.1 I...-..I-.l...J.J..J.J..u..._-'-.....L.-'-J....LJUJ.l_--'_L-L..LLlllJ
20
100
1,000
10,000
IMPULSE DURATION (I's)

10,000

,

1

FIGURE 16. SURGE CURRENT RATING CURVES FOR
V130CP22 - V150CP22

NOTE: If pulse ratings are exceeded, a shift of VN(OC} (at specified current) of more than ±10% could result. This type of shift, which normally results in a decrease of V N(OC}, may result in the device not meeting the original published specifications, but it does not prevent the
device from continuing to function, and to provide ample protection.

Packaging
DfMENSIONS

PART
SIZE

- - 0.200
MIN
(0.008)

INTERNAL
DIAMETER (0 1)

EXTERNAL
DIAMETER (D2.1

PASSIVATION
DIAMETER (03)

MIN

MAX

MIN

MAX

MIN

MAX

22A

0.86
(0.034)

1.02
(0.040)

1.73
(0.068)

1.88
(0.074)

1.83
(0.072)

1.98
(0.078)

229

0.86
(0.034)

1.25
(0.049)

1.73
(0.068)

1.S8
(0.074)

1.83
(0.072)

1.98
(0.078)

20A

1.09
(0.043)

1.25
(0.049)

2.08
(0.082)

2.39
(0.094)

2.18
(0.086)

2.54
(0.100)

209

1.09
(0.043)

1.83
(0.072)

2.08
(0.082)

2.39
(0.094)

2.18
(0.086)

2.54
(0.100)

0:: en
011-0

l6A

2.27
(0.090)

2.41
(0.095)

3.40
(0.134)

3.56
(0.140)

3.50
(0.138)

3.56
(0.144)

0::0

NOTE: Dimensions in millimeters and (inches)

9-47

en=>
-0
~g:

CS Series

H.ARRlS
SEMICONDUCTOR

Connector Pin Metal-Oxide Varistors

August 1993

Features
• Unique Coaxial Design and Mounting Arrangement
• Wide Operating Voltage Range VM(OC) ••••••••••••••••• 8V to 38V
• Self Contained Tubular Construction; Requires No Leads or Packages

CSSERIES

• New Reduced Length; Less Than Half the Length of Standard CP
Series

Description
CS series transient surge suppressors are connector pin
metal.oxide varistors that utilize a self contained tubular construction requiring no leads or packages. They are designed
to provide transient surge protection in connector/filter applications in aerospace, automotive, computer and associated
industries. These varistors are available in a wide range of
voltage rating from 8V oc to 38V oc.

The CS series of connector suppressors are of similar package construction to the Harris CP series, but differ in size,
ratings and characteristics. They offer the advantage of
small size and light weight; key benefits in connector assemblies. The unique coaxial mounting arrangement of the CS
series allows them to become an integral part of a transmission line; thus, inductive lead effects are eliminated.

Absolute Maximum Ratings For ratings of individual members of a series, see Device Ratings and Characteristics chart

Continuous:
Steady State Applied Voltage:
DC Voltage Range (VM(DC» ...................................................•..
Transient:
Peak Pulse Current (I TM )
For 8I201ls Current Wave (See Figure 2) ........................................... .
Single Pulse Energy Range (WTM)
For 1011 OOOIlS Current Wave .................................................... .

CS SERIES

UNITS

8 to 38

V

80 to 100

A

0.5

J

•••••••••••••••••••••••••••••••••••••••••••

-55 to +125

°C

Storage Temperature Range (TSTG)' ................................................ .

-5510 +150

°C

Temperature Coellicient (exV) of Clamping Voltage (Vcl at Specified Test Current ............. .

<0.01

o/oI"C

Operating Ambient Temperature Range (TA)

Copyright © Harris Corporation

1993

File Number
9-48

2972.1

Specifications CS Series
Device Ratings and Characteristics
MAXIMUM RATINGS (+12S0 C)

CONTINUOUS

CHARACTERISTICS (+2SOC)
VARISTOR
VOLTAGE
AT lmA DC TEST
CURRENT

TRANSIENT

DC
VOLTAGE

ENERGY
(101
1000J1S)

PEAK
CURRENT
(8120).15)

VN(OC)

MAXIMUM
CLAMPING
VOLTAGEVc
AT lOA
(8120).1s)

CAPACITANCE AT
f lMHz

=

C

VU(DC)

Wm

PART
SIZE

1m

(V)

(V)

(A)

V8CS22

228

8

0.5

80

13.5

19.5

36

830

1400

Vl4CS22

228

14

0.5

80

18.5

25.5

44

675

1125

V18CS22

228

18

0.5

80

22.5

27.9

47

600

1100

V22CS22

228

22

0.5

100

27.5

34.5

57

540

950

V26CS22

228

26

0.5

100

29.5

36.5

68

510

870

V31CS22

228

31

0.5

100

35.0

48.0

85

450

800

V38CS22

228

38

0.5

100

42.0

58.0

100

350

700

MODEL
NUMBER

MIN

MAX

Vc

(V)

(V)

MAX

MIN
(pF)

NOTE: Average power dissipation of transienJs not to exceed 200mW

LEAKAGE CURRENT AT VU(DC)
+2SoC

+12SoC

IL TYP

ILMAX

IL TYP

ILMAX

(j.lA)

!l!A)

(j.lA)

(IIA)

V8CS22

0.5

5.0

5.0

50

V14CS22

0.5

5.0

5.0

50

V18CS22

0.5

5.0

5.0

50

V22CS22

0.5

5.0

5.0

50

V26CS22

0.5

5.0

5.0

50

V31CS22

0.5

5.0

5.0

50

V38CS22

0.5

5.0

5.0

50

MODEL NUMBER

9-49

a:cn
oJJ-O
cn~
-0
a:O

~g:

CS Series
Power Dissipation Requirements

.A
100

Transients in a suppressor generate heat too quickly for it to
be transferred to the surroundings during the pulse interval.
Continuous power dissipation capability, therefore is not a
necessary requirement for a suppressor, unless transients
occur in rapid succession. Under this condition, the average
power dissipation required is simply the energy (watt·
seconds) per pulse times the number of pulses per second.
The power so developed must be within the specifications
shown on the Device Ratings and Characteristics table for
the specific device. Furthermore, the operating values need
to be derated at high temperatures as shown in Figure 1.
Because varistors can only dissipate a relatively small
amount of average power they are, therefore, not suitable for
repetitive applications that involve substantial amounts for
average power dissipation.

~ 70
w 60
!;(

\

0

...II:0

...z

w

()

II:

...w

50

\

40
30

\

20

\

10

o~
-55

50

60

,

70 80 90 100 110 120 130 140 150
AMBIENT TEMPERATURE (OC)

FIGURE 1. CURRENT, ENERGY AND POWER DERATING
CURVE

w

MAX CLAMPING VOLTAGE
MODEL SIZE 22 GAUGE
8VM(DC) TO 38VM(DC) RATING

:3
~

~

100 TA = ·55"C TO ...1250 C

...
~
...z
w

...

~

V38CS22
V31CS22
V28CS22
V22CS22
V18CS22;::::
V14CS22

...ffi

0, = Virtual Origin Of Wave
T = Time From t 0% To 90% Of Peak

=

\

w 90
::> 80
..J

=

T, Virtual Front Time 1.25 x T
T2 = Virtual Time To Half Value
(Impulse Duration)

EXAMPLE:
For an 8/20~s Current
Waveform:
8~s = T, = Virtual Front Time
20~ = T2 = Virtual Time to Half
Value

10

rr~ir

lmA

FIGURE 2. PEAK PULSE CURRENT TEST WAVEFORM

-

,.
....

~

10mA
100mA
lA
PEAK AMPERES (A)

lOA

100A

FIGURE 4. CLAMPING VOLTAGE FOR V8CS22· V38CS22

Packaging
DIMENSIONS

PART
SIZE
22B

INTERNAL
DIAMETER (01)

EXTERNAL
DIAMETER (02)

MIN

MAX

MIN

MAX

MIN

MAX

0.86
(0.034)

1.25
(0.049)

1.73
(0.068)

1.88
(0.074)

1.83
(0.072)

1.98
(0.078)

NOTE: Dimensions in millimeters and (inches)

"CS" DIMENSION OUTLINE

NOTE:
1. The CS series of connector pin varistors may also be obtained in
gauge sizes 16A, 20A, 20B, and 22A AWG, and with continuous
operating voltages of up to 100 volts dc. For information on avail·
ability of different voltages and sizes, please contact Harris
Semiconductor Power Marketing.

9·50

PASSIVATION
DIAMETER (03)

HARRIS
SEMICONDUCTOR

DAfDB Series
Industrial High Energy Metal-Oxide Varistors

August 1993

Features
• Recognized as "Transient Voltage Surge Suppressors", UL File
#E75961 to Std. 1449
• High Energy Absorption Capability WTM •••••••••••• Up To 1050J
• Wide Operating Voltage Range VM(AC)RMS ..•.••••••• 130V to 750V
• Rigid Terminals for Secure Wire Contact (DA Series)
• Case Design Provides Compiete Electrical Isolation of Disc
Subassembly
DA SERIES

DB SERIES

• Large Diameter Disc •••••••.••••••••••••••.••.••.•••••• 40mm

Description
DA and DB series transient surge suppressors are heavyduty industrial metal-oxide varistors designed to provide
surge protection for motor controls and power supplies used
in oil-drilling, mining, and transportation equipment. Possible
voltage surges in their ac power supplies could cause product failure and the subsequent faulty operation of these systems.

These UL-recognized varistors have identical ratings and
characteristics but differ in case construction to provide flexibility in eqUipment designs.
DA series devices feature rigid terminals to insure secure
wire contacts. Both the DA and DB series feature improved
creep and strike distance capability to minimize breakdown
along the package surface design that provides complete
electrical isolation of the disc subassembly.

Absolute Maximum Ratings For ratings of individual members of a series, see Device Ratings and Characteristics chart

Continuous:
Steady State Applied Voltage:
AC Voltage Range (VM(AC)RMS) ................................................... .
DC Voltage Range (VM(DC) ..................................................... .

DAIDB SERIES

UNITS

130 to 750
175 to 970

V
V

a:~
~()

(/)::::1

-0

Transient:
Peak Pulse Current (lTM)
For Bl20l1s Current Wave (See Figure 2) ........................................... .
Single Pulse Energy Range
For 1011 OOOI1S Current Wave (WTM ) ............................................... .

30,000 to 40,000
270 to 1050

J

Operating Ambient Temperature Range (TA) .......................................... .

-55 to +85

°C

a:O

~g:

A

Storage Temperature Range (TsTa) ................................................. .

-55 to +125

°C

Temperature Coefficient (a.V) of Clamping Voltage (Vel at Specified Test Current ............. .

<0.01

%?C

Hi·Pot Encapsulation (Isolation Voltage Capability) ..................................... .
(Dielectric must withstand indicated DC voltage for one minute per MIL·STD 202, Method 301)

5000

V

Insulation Resistance; ........................................................... .

1000

Mil

Copyright © Harris Corporation 1993

File Number

9-51

2189.2

Specifications DAiDB Series
Device Ratings and Characteristics
Series DA and DB Varistors are listed under UL file #E75961 as a UL recognized component.
MAXIMUM RATINGS (+85°C)
CONTINUOUS

TYPICAL
CAPACITANCE

DC
VOLTAGE

ENERGY
(101
10001lS)

PEAK
CURRENT
(8120IlS)

VM(AC)

VM(DC)

WTM

ITM

MIN

VN(DC)

MAX

Vc

1= lMHz

(V)

(V)

(J)

(A)

(V)

(V)

(V)

(V)

(pF)

DB

VARISTOR VOLTAGE
AT lmA DC TEST
CURRENT

MAX
CLAMPING
VOLTVc
AT200A
CURRENT
(812OIlS)

RMS
VOLTAGE
MODEL NUMBER
DA

CHARACTERISTICS (+25°C)

TRANSIENT

V131DA40

V131DB40

130

175

270

30000

184

200

228

345

10000

V151DA40

V151DB40

150

200

300

30000

212

240

268

405

8000

V251DA40

V251DB40

250

330

370

30000

354

390

429

650

5000

V271DA40

V271DB40

275

369

400

30000

389

430

473

730

4500

V321DA40

V321DB40

320

420

460

30000

462

510

539

830

3800

V421DA40

V421DB40

420

560

600

40000

610

680

748

1130

3000

V481DA40

V481DB40

480

640

650

40000

670

750

825

1240

2700

V511DA40

V511DB40

510

675

700

40000

735

820

910

1350

2500

V571DA40

V571DB40

575

730

770

40000

805

910

1000

1480

2200

V661DA40

V661DB40

660

850

900

40000

940

1050

1160

1720

2000

V751DA40

V751DB40

750

970

1050

40000

1080

1200

1320

2000

1800

NOTE: Average power dissipation of transients not to exceed 2.0W.

Power Dissipation Requirements
Transients in a suppressor generate heat too quickly for it to
be transferred to the surroundings during the pulse interval.
Continuous power dissipation capability, therefore, is not a
necessary design requirement for a suppressor, unless transients occur in rapid succession. Under this condition, the
average power dissipation required is simply the energy
(watt-seconds) per pulse times the number of pulses per
second. The power so developed must be within the specifications shown on the Device Ratings and Characteristics
table for the specific device. Furthermore, the operating values need to be derated at high temperatures as shown in
Figure 1. Because varistors can only dissipate a relatively
small amount of average power they are, therefore, not suitable for repetitive applications that involve substantial
amounts of average power dissipation.

100
w
::> 90
oJ

~

1\

80

\.

0

w 70

!i( 60
a:

I\,
\

"- 50

...0z

40

w 30

()

a:
w
Q.

\.

20

10~_r--r__r--r__+--r__+--~_+--r__i

II "
-55 50

60

70

80

90

\.
100 110 120 130 140 150

AMBIENT TEMPERATURE (Oc)

FIGURE 1. CURRENT, ENERGY AND POWER DERATING
CURVE

w 100 -------------

~

90 ----------

~

, ,

W
Q.

t

...z
~

50

'

, '
-------: , ---'---r-------

..."

,

"

~ 10 - ,

0 1 = Virtual Origin of Wave
T = Time From 10% to 90% of Peak
T 1 =Virtual Front Time =1.25 • t
T2 =Virtual Time to Half Value (Impulse Duration)
Example: For an 8120J,ls Current Waveform:
81ls = T 1 = Virtual Front Tima
20llS =T2 =Virtual Time to Half Value

01~~r-~--'T-~T-~+--r----~-T-I-M-E--T2----I

FIGURE 2. PEAK PULSE CURRENT TEST WAVEFORM

9-52

DAfDB Series
Transient V-I Characteristics Curves
6,000
5,000
4,000
~
fI)

!:i

g
~
~

~~
~
~

t-H

MAXIMUM CLAMPING VOLTAGE
TA = -550C to +850C
DISC SIZE 40mm
V751DAlDB40
130 TO 750 VM(AC) RATING
V661DAlDB40.i.....:
3,000 I- V511DAlDB40
V571DAlDB40
V481DAlDB40
2,000
V421DAlDB40

P
1,000

~
~

;88
600
500
400

300

V151 DAlDB40

~

1\

V13~ ~AlDB40

200
1M

1M

100

1~

V321 DAlDB40
V271 DAlDB40
V251DAlDB40

1~

1~

1~

1~

PEAK AMPERES (A)

FIGURE 3_ CLAMPING VOLTAGE FOR V131 OA40, V131 OB40 - V751 OA40, V7510B40

Pulse Rating Curves

50,000
20,000
10,000

r-..,.1

l'l'

50,000

DISC SIZE 40mm
2

10

-l-H-Hf++ V131 DA40 - V321 DA40

I I II

20,000

V131 DB40 - V321 DB40

~

:>
0

w

CI

a:

:>
fI)

1,000

100

.......... ~~)

~ 1,000

:>
0

.......

Jr...

r-

y"""

w

/

CI

...... 1"--

:>

20 INFErlr\TFI......
100

fI)

-"

500

a: 200

50

1020

1111

...2; ;:1'--

1,000
IMPULSE DURATION (~)

100
50

~03

-

FIGURE 4. SURGE CURRENT RATING CURVES FOR
V1310A40, V1310B40 - V321 OA40, V3210B40

.......... .'>"~

.......

20
10,000

1020

~:~~g~~g:~mg~~g

104
. / 10~06

ffi 2,000 ~

500
200

DISC SIZE 40mm

10

g5,OOO

.......

.J.03

2

~

10,000

g5,OOO 102

!z 2,000

~

J?-,t.

["Y....,.

I~D~Fltri111
100

r-.
-;-

~ ~r-.

1,000
IMPULSE DURATION (I's)

a:(J)
10,000

FIGURE 5. SURGE CURRENT RATING CURVES FOR
V4210A40, V421 OB40 - V751 OA40

NOTE: If pulse ratings are exceeded, a shift of VN(OC) (at specified current) of more than ±10% could result. This type of shift, which normally
results in a decrease of VN(OC), may result in the device not meeting the original published specifications, but it does not prevent the device
from continuing to function, and to provide ample protection.

9-53

011-(.)

(J)::l
-0
a:O

~g:

DAIDB Series
Packaging
DA SERIES

DB SERIES

"An DIMENSION:
FILISTER HEAD SCREW· 51 mm (2.01)
PAN HEAD SCREW· 53mm (2.09)

ALL DIMENSIONS ARE MAXIMUM
EXCEPT WHERE NOTED

HOLES 0.21 THRU
BORE 0.343 x 0.328 DP

t
1~.r;:i

G

j i~

~

IT

1-J..1-62mf--m--1-J
(2.44) - - - j 4.5mm (0.18)

r----

Dimensions in millimeters and (inches).

9·54

HA Series

I-lARRiS
SEMICONDUCTOR

Industrial High Energy Metal-Oxide Varistors

August 1993

Features
• Recognized as "Transient Voltage Surge Suppressors", UL File
#E75961 to Std. 1449
• Recognised as "Transient Voltage Surge Suppressors", CSA File
#LR91788 to Standard C22.2 No. 1-M1981
• Wide Operating Voltage Range VM(AC)RMS ••••••••••• 130V to 750V
• Two Model Sizes Available ••••••••••••••••••••• 32mm and 40mm
• High Energy Absorption Capability ••••••••••• W TM
• High Peak Pulse Current Capability • • • • •• ITM
HASERIES

= 200J to 1050J

= 25,OOOA to 40,OOOA

• Rigid Terminals for Secure Mounting
• Available In Clipped Version for Through Hole Board Mounting •
Designation "HC"

Description
HA series transient surge suppressors are industrial high
energy metal·oxide varistors. They are designed to provide
secondary surge protection in the outdoor and service
entrance environment (distribution panels), in computers,
and also in industrial applications for motor controls and
power supplies used in the oil·drilling, mining, and transpor·
tation fields. Possible voltage transients in the ac power net·
work could cause product failure and the subsequent faulty
operation of these systems.

The HA series of industrial varistors have similar package
construction but differ in size, (32mm and 40mm), ratings
and characteristics. The design of the HA series of metal
oxide varistors provide rigid terminals to insure secure
mounting. Also available in a clipped version for through hole
board placement· designation "He".

Absolute Maximum Ratings For ratings of individual members of a series, see Device Ratings and Characteristics chart
HA SERIES
Continuous:
Steady State Applied Voltage:
AC Voltage Range (VM(AC)RMS)' •••••••••••••••••••••••••••••••••••••••••••••••••••
DC Voltage Range (V M(DC) ••••••••••••••••••••••••••••••••••••••••••••••••••••••

UNITS

130 to 750
175 to 970

V
V

Transient:
Peak Pulse Current (lTM)
For 8120~ Current Wave (See Figure 2) .......................•....•...............
Single Pulse Energy Range
For 10/1 OOO~ Current Wave (WTM ) ....••..•..••..•.....•.•..•..•..•••••.••.••••..•

25,000 to 40,000

A

200 to 1050

J

Operating Ambient Temperature Range (TAl .......................................... .

-55 to +85

°C

Storage Temperature Range (TSTG)'

-0
a:: 0

~g:

-55 to +125

°C

Temperature Coefficient (aV) of Clamping Voltage (Vel at Specified Test Current ............. .

<0.01

%f'C

Hi·Pot Encapsulation (Isolation Voltage Capability) ..................................... .
(Dielectric must withstand indicated DC voltage for one minute per MIL·STD 202,
Method 301)

2500

V

Insulation Resistance ............................................................ .

1000

M!l

•.••.••.••.•••..•....•..•......•••••••.••.••••.••

Copyright © Harris Corporation 1993

File Number
9-55

a:: en
U
en:::>

01I-

2973.2

Specifications HA Series
Device Ratings and Characteristics
HA Series varistors are listed under CSA File #LR91788 as a recognized component.
HA Series varistors are listed under U.L. File #E75961 as a recognized component.
MAXIMUM RATINGS (+85°C)
CONTINUOUS

CHARACTERISTICS (+25°C)

TRANSIENT

ENERGY
(10/1000j.1s)

PEAK
CURRENT
(8120j.1S)

VM(DC)

WTM

1m

MIN

VN(DC)

MAX

Vc

C

(V)

ENERGY

(A)

(V)

(V)

(V)

(V)

(pF)

130
130

175
175

200
270

25000
30000

184
184

200
200

228
228

350
345

4700
10000

V151HA32
V151HA40

150
150

200
200

220
300

25000
30000

212
212

240
240

268
268

410
405

4000
8000

V251HA32
V251HA40

250
250

330
330

330
370

25000
40000

354
354

390
390

429
429

650
630

2500
5000

V271HA32
V271HA40

275
275

369
369

360
400

25000
40000

389
389

430
430

473
473

710
690

2200
4500

V321HA32
V321HA40

320
320

420
420

390
460

25000
40000

462
462

510
510

539
539

845
825

1900
3800

V421HA32
V421HA40

420
420

560
560

400
600

25000
40000

610
610

680
680

748
748

1120
1100

1500
3000

V481HA32
V481HA40

480
480

640
640

450
650

25000
40000

670
670

750
750

825
825

1290
1230

1300
2700

V511HA32
V511HA40

510
510

675
675

500
700

25000
40000

735
735

820
820

910
910

1355
1295

1200
2500

V571HA32
V571HA40

575
575

730
730

550
770

25000
40000

805
805

910
910

1000
1000

1570
1480

1100
2200

V661HA32
V661HA40

660
660

850
850

600
900

25000
40000

940
940

1050
1050

1160
1160

1820
1720

1000
2000

V751HA32
V751HA40

750
750

970
970

700
1050

25000
40000

1080
1080

1200
1200

1320
1320

2050
2000

800
1800

RMS
VOLTAGE

DC
VOLTAGE

VM(AC)

(V)

V131HA32
V131HA40

MODEL
NUMBER

VARISTOR VOLTAGE
AT 1 mA DC TEST
CURRENT

MAXIMUM
CLAMPING
VOLTAGE
(Vel AT 200
Amps (8/20j.1s)

TYPICAL
CAPACITANCE
AT!: 1MHz

NOTE: Average power disSipation of transients not to exceed 1.5W and 2.0W for model sizes 32mm and 40mm, respectively.

Power Dissipation Requirements

.A

Transients in a suppressor generate heat too quickly for it to
be transferred to the surroundings during the pulse interval.
Continuous power dissipation capability, therefore is not a
necessary requirement for a suppressor, unless transients
occur in rapid succession. Under this condition, the average
power dissipation required is simply the energy (wait-seconds) per pulse times the number of pulses per second. The
power so developed must be within the specifications shown
on the Device Ratings and Characteristics table for the specific device. Furthermore, the operating values need to be
derated at high temperatures as shown in Figure 1. Because
varistors can only dissipate a relatively small amount of average power they are, therefore, not suitable for repetitive
applications that involve substantial amounts for average
power dissipation.

9-56

w

:::>

90

~

80
70

-'
0

w

tc

II:

"-

...0z
w

(J

II:

w

""

,

100

~

"

60
50
40
30

"

20
10

o

", ,

.A

-55

50

60

70

80

\.

"

90 100 110 120 130 140 150

AMBIENT TEMPERATURE (OC)

FIGURE 1. CURRENT, ENERGY AND POWER DERATING
CURVE

HA Series
w

3100

;;

=
=

~ 90
w

0 1 Virtual Origin of Wave
T Time From 10% to 90% of Peak
Tl = Virtual Front Time = 1.25. t
T2 Virtual Time to Half Value (Impulse Duration)

Q.

~
~

=

50

w

Example: For an 8I20~ Current Waveform:
8~ Tl
Virtual Front Time
20~ = T2 = Virtual Time to Half Value

(J

= =

ffiQ.
01

TIME

FIGURE 2. PEAK PULSE CURRENT WAVEFORM

Transient V-I Characteristics Curves
6,000
5,000
4,000

IIIII11
!:i 2,000 V751HA32
!S!
V661HA32
Q.

::E

::>

::E
~
::E

900
800
700
600
500
400

300

~

V571HA32
V511HA32
V481HA32
V421HA32
V321HA32
V271HA32
V251HA32

4,000

~3,OOO V511HA4~\

~

~

V421HA4

~

~ l,gS8
::E 700
600
~ 500

i

400
300

VWI~~2

10.2

IVJm~t30

~ 2'OOO~~V148]1~H~A4!O~:\I;IIIV517flIHAI41°lilllli/~~
~

!S!

~

V~~11~~2

200
10.3

MAXIMUM CLAMPING VOLTAGE TA = -550 C to +850 C
DISC SIZE 40mm
+1-tH1Itt-++ttlttlt-"~Httll
130 TO 750 VM(AC) RATING
~

5,000

~
~

~3,OOO
III

~
w 1,000

6,OOO..-----------TT~-----..."

TA= -55 0 C to +85OC

MAXIMUM CLAMPtNG VOLTAGE
MODEL SIZE 32mm
130 TO 750VM(AC) RATING

f-~~V~15~1~HM~Omi:ml~ml:flmi\
;"i,
I~~I~~~O

V321HMO
V271HMO

V~~,~,~MO

200~~~~~~LllWW~LW~~~~LUllim~LW~

10.1

100
101
102
PEAK AMPERES (A)

10 3

104

105

10.2

FIGURE 3. CLAMPING VOLTAGE FOR V131HA32· V751HA32

10.1

100

101
102
103
PEAK AMPERES (A)

10 4

105

FIGURE 4. CLAMPING VOLTAGE FOR V131HA40· V751HA40

Pulse Rating Curves
0:

50,000
20,000
10,000

g

...z
w

(J

w

<:I

a:

::>

III

Kl

~"

5,000 .J.O

500

~

r-....

~
100
20
10

1-0.. .........

10

-I~DT~~IT~
20

100

t-.... r-.

-

r--..

r-

r-....

500

~

a:

200
100

f.J.E:

<:I

~

::>

III

........ r-....

-........: t"t'-

10

w

(J

200

50

~ 1,000

::>

~

-+-++-1+1-

g 5,000
ffi 2,000 ~
3

".-........: t'--.

2,000 102

a: 1,000
a:

::>

50,000 c:;l::j=t:!fl±E==t:=t=t:+f~;;~;;-;.;,;;c-r-"1
DISC SIZE 40mm
V131 HMO· V151 HA40
20,000 k.:'N""k:+-++ 2
10,000
V~ 10

DISC SIZE 32mm
V131 HA32 • V751 HA32

~

.........

~ ....... 1'--

50

.........

r--.......... .:::::: ....

1,000
IMPULSE DURATION (~s)
FIGURE 5. SURGE CURRENT RATING CURVES FOR
V131 HA32· V751 HA32

20 r=liD,E,lilm 10,000

9·57

1020

100

-r-.

~ ~"

1,000
IMPULSE DURATION {j1s)
FIGURE 6. SURGE CURRENT RATING CURVES FOR
V131HA40· V151HA40

10,000

en

011-0
en::l
-0
0:0

~g:

HA Series
Pulse Rating Curves (Continued)
DISC SIZE 40mm
~~~·~':ar7~ll~m~~~:f~~~
V251 HA40 - V751 HA40
~

50,000
20,000 ~-,.....P'-I;;:tt- ,2 10

1B'I~~I'~II~~~~II~
1' .....

g5'000~
10,000

!z 2,000 L '0'

~~

:;:~

.............

§~~III~~~~II~~IIIII
~
......................

500~

1,000

200 1--f..J.2:..:"g6~o:I-t-f'l"! 90
..J

~ 80

'\.

0

w 70

It
a:

60
"- 50
....
zw 40
() 30

'\.

°

\
\.

"-

a: 20
w
A-

10

o

-55

'\.
50

60

70 80 90 100 110 120 130 140 150
AMBIENT TEMPERATURE (OC)
FIGURE 1. CURRENT, ENERGY AND POWER DERATING
CURVE

w 100

::>

..J

0, = Virtual Origin of Wave
T =Time From 10% to 90% of Peak
T, =Virtual Front Time =1.25 • t
T2 =Virtual Time to Half Value (Impulse Duration)
Example: For an 8120~ Current Waveform:
ails =T, =Virtual Front Time
20~ =T2 =Virtual Time to Half Value

~ 90
~



:;

~

II

:;

~';'50LA5

10-1

101
102
100
PEAK AMPERES (A)

103

:;;

U;
!J

fff5,000 f-

3,000
2,000

~ 2,000

I

:;
:::>

~~6~0(~~1!

l-

~
~

~

~
?'

i.-:

:;
:::>
:;

~

V575LA40A
V510LA40A
V4S0LA40A
V420LA20A
1111
10.1

10.2

100
101
102
PEAK AMPERES (A)

:;

104

7,000
6,000
:;; 5,000

c..
~

~
:;

400

V275LA40A

-I m~tr+OA'
10.2

r--

~

~ 2,000

f-

r

1111111

~

r-IIIIIIIII 111111

~
:;

300 f- V150LA20B

IIIIIIII!~
V130LA20B

200
10.3

10.2

10.1

100
101
102
PEAK AMPERES (A)

100
101
102
PEAK AMPERES (A)

103

104

FIGURE 9. CLAMPING VOLTAGE FOR V130LA20B - V275LA40B

111111

1111111111111111

103

1~1;I~ooL~;~~IB

1111111
11111111

'il

1111111

V575LAeOB
V51 OLASOB
I V4S0LASOB
V420LASOB

fo-

,;'"

f---

~!oWlb~l~

:;
:::>
:;

V275LA40B
V250WOS"

10.1

MODEL SIZE 20mm
320 TO I,OOOVM(A91 RATING
TA = -55°C TO +S5 C

~ 3,000

r-

""

V175LA20

V150LA20A

U; 4,000
!J

!:i
~ 1,000

:;

MAXIMUM CLAMPING VOLTAGE
MODEL SIZE 20mm
130 TO 275VM(AC) RATING
TA = -55°C TO +S5OC

3;ggg r-- MAXIMUM CLAMPING VOLTAGE

(/)

;;5

104

104

FIGURE 8. CLAMPING VOLTAGE FOR V130LA20A - V275LA40A

MAXIMUM CLAMPING VOLTAGE
MODEL SIZE 20mm
2,000 I- 130 TO 275VM(AC~ RATING
TA = -55°C TO +S °C

900
SOO
700
600
500

400

200
10.3

3,000

~

103

IV\3~1~:o,;

11111
103

900
SOO
700
600 500

300

FIGURE 7. CLAMPING VOLTAGE FOR V420LA20AV1000LA80A

~

100
101
102
PEAK AMPERES (A)

~ 1,000

""

:;~ l,ggg
SOO
700
600
500
10.3

10.1

Vl

I-

:;

10.2

!J

~~I~O~~~~I~~

~

I-

~

IIIIUII~1

~ 3,000

V150LA10A
V140LA10A
V130LA10A

FIGURE 6. CLAMPING VOLTAGE FOR V130LA 1OA - V320LA20A

MAXIMUM CLAMPING VOLTAGE
MODEL SIZE 14mm
420 TO 1.000VM(A1,l RATING
TA = -55°C TO +85 C
111111 111111111

4,000

·W~~~A

200
10-3

104

~

f- V420LA10

1111111iT1

FIGURE 5. CLAMPING VOLTAGE FOR V130LA5 - V420LA10

9,000
S,OOO
7,000
6,000

SOO
700
600
500
400
300

V140LA5
V130LA5

10.2

Ij~~250LA20A
V230LA20A

~
~ 1'~88

R

~gg

V275LA20A

~

~

V4~~~,Al0

600
500
400

11111111

~ 2,000

'""'"

2,000

MAXIMUM CLAMPING VOLTAGE
MODEL SIZE 14mm
130 TO 320VM(AC) RATING
TA = -55°C TO +S5OC

r=

1,000
900
SOO f--700 r600 f--500 ' 10.3

...
10.2

V320LA40B
10.1

100
101
102
PEAK AMPERES (A)

FIGURE 10. CLAMPING VOLTAGE FOR V320LA40BV1 OOOLA 160B

9-62

~
~

LA Series

Pulse Rating Curves
5,000
21'

1,000

ll!

200

~
(.)

100

~
IX:

ii:

.......

r-..

..........

K tY-k

r--

---

""".
~S

50
20

:-----;:

INDEFINITE

10

5
100

1,000
IMPULSE DURATION (~s)

FIGURE 11. SURGE CURRENT RATING CURVES FORV130LA1
• V300LA4

5,000

...
LU

200

:>

t-....
100

Z

IX:
IX:
(.)

LU

CJ
IX:
:>
Ul

102
103

~

........ :) F,(~

r-INDEFINITE

10

g

.".

50
20

2,000

~1045
10106

500

5

2
20

--2
10=

.......

......

_1,000
~ 500
200
100

LU

50

(.)

CJ
IX:
:>
Ul

:::>

t-....
100

"' .....

t-....

2

20

106

r.::::

........ :) ry,::Y-

r--

10

10,000

..,.
t--

50
20

5

=

...

:>

200

Ul

100
1,000
IMPULSE DURATION (~s)

1

5.000

Z
LU

w

102
103

~104105

INDEFINITE

----

r,

r---'-_

:--....r-..

:::::;::: 8::~

100
1,000
IMPULSE DURATION (~s)

10,000

FIGURE 14. SURGE CURRENT RATING CURVES FOR
V420LA20A· V1 000LA80A

a:: m

10,000

IX:
IX:

IX:
IX:

CJ
:::>

FIGURE 13. SURGE CURRENT RATING CURVES FOR
V130LA lOA· V320LA20A

2,000

1,000

IX:

~ :::::::::::

10,000

MODEL SIZE 14mm
V420LA20A· Vl 000LA80A

;-;:--.

...z
(.)

r---'-_

~

1,000
IMPULSE DURATION (~s)

t's;.1
2

500

w

r'

..........

FIGURE 12. SURGE CURRENT RATING CURVES FOR V130LA5
• V420LA 10

MODEL SIZE 14mm
V130LA10A· V320LA20A

;-;:--.

1,000

100

20

5,000

I"'<;:: 1

2,000 ",2

g

2

10,000

102 3
10 4
10 5
10106

10

...g 500
z

MODEL SIZE 10mm
V130LA5· V420LA10

K

2,000

""'<:,

20
10

INDEFINIT

E --

5

.~

-

011-0
m::::l
-0

MODEL SIZE 20mm
V130LA20A • V320LA40B
102
103
104
105
106

a:: 0
~g:

I'-..

~ :::::-

~

5

2
120

2
100

1,000
IMPULSE DURATION (~s)

FIGURE 15. SURGE CURRENT RATING CURVES FOR
V130LA20A· V320LA40B

120

10,000

100

1,000
IMPULSE DURATION (~s)

10,000

FIGURE 16. SURGE CURRENT RATING CURVES FOR
V420LA40B· V1000LA160B

NOTE: If pulse ratings are exceeded, a shift of VN(DC) (at specified current) of more than ±10% could result. This type of shift, which normally
results in a decrease of VN(DC)' may result in the device not meeting the original published specifications, but does not prevent the device from
continuing to function, and to provide ample protection.

9·63

, LA Series
Tape and Reel Specifications

Tape And Reel Data
• Conforms to ANSI and EIA specifications

Ah--i I--Ah

• Can be supplied to IEC Publication 286-2
• Radial devices on tape are supplied with crimped
leads. straight leads. or under-crimped leads

CRIMPED LEADS

"IT"

1.-~-tI+'J
!

H,

Ii

STRAIGHT LEADS
"lS·

UNOER-<:RIMPED
lEADS "lU·

MODEL SIZE
PARAMETER

SYMBOL
P

Pitch of Component

7mm

10mm

14mm

20mm

12,7± 1.0

25.4± 1.0

25.4± 1.0

25.4 ± 1.0
12.7 ± 0.2

Po

Feed Hole Pitch

12,7 ± 0.2

12.7 ± 0.2

12.7 ± 0.2

P,

Feed Hole Center to Pitch

3.85 ± 0.7

2.6± 0.7

2.6±0.7

2.6 ± 0.7

P2

Hole Center to Component Center

6.35 ± 0.7

6.35±0.7

6.35±0.7

6.35 ± 0.7
7.5±0.8

F

Lead to Lead Distance

5.0 ± O.B

7.5 ± 0.8

7.5 ± 0.8

lIh

Component Alignment

2.0 Max

2.0 Max

2.0 Max

2.0 Max

W

Tape Width

18.0 + 1.0
18.0 - 0.5

18.0+ 1.0
18.0 - 0.5

18.0+1.0
18.0 - 0.5

18.0+1.0
18.0 - 0.5

Wo

Hold Down Tape Width

W,

Hole Position

W2
H

6.0± 0.3

6.0 ± 0.3

6.0± 0.3

12.0 ± 0.3

9.0+0.75
9.0 - 0.50

9.0+0.75
9.0 - 0.50

9.0 + 0.75
9.0 - 0.50

9.0 +0.75
9.0 - 0.50

0.5 Max

0.5 Max

0.5 Max

0.5 Max

Height from Tape Center to Component
Base

18.0 + 2.0
1B.0 - 0.0

18.0 + 2.0
18.0 - 0.0

18.0 + 2.0
18.0 - 0.0

18.0 +2.0
18.0 - 0.0

Hold Down Tape Position

Ho

Seating Plane Height

16.0 ± 0.5

16.0 ± 0.5

16.0 ± 0.5

16.0 ± 0.5

H,

Component Height

32.0 Max

36.0 Max

40.0 Max

46.5 Max

Do

Feed Hole Diameter

4.0± 0.2

4.0 ± 0.2

4.0 ±0.2

4.0± 0.2

t

Total Tape Thickness

0.7 ±0.2

0.7±0.2

0.7 ± 0.2

0.7 ± 0.2

L

Length of Clipped Lead

11.0 Max

11.0 Max

11.0 Max

11.0 Max

lip

Component Alignment

3"Max
1.00mm

3° Max
1.00mm

3° Max
1.00mm

3" Max

NOTE: DimenSions are In mm.

LA Series

Tape and Reel Ordering Information

SHIPPING QUANTITY

Crimped leads are standard on LA types supplied in tape
and reel and are denoted by the model letter "T'. Model letter "S" denotes straight leads and letter "U" denotes special
under-crimped leads.
Example:

10mm
14mm
14mm

STANDARD
MODEL

CRIMPED
LEADS

V130LA2

STRAIGHT
LEADS

VI30LT2

VI30LS2

UNDERCRIMPED
LEADS
VI30LU2

QUANTITY PER REEL

SIZE

RMS
(MAX)
VOLTAGE

"T" REEL

"S" REEL

"U" REEL

7mm

All

1000

1000

1000

All

1000

1000

1000

<300V

500

500

500

~300V

500

500

500

20mm

<300V

500

500

500

20mm

5:300V

500

500

500

Packaging
VARISTOR MODEL SIZE

t0D~T
A

SYMBOL
A

P~
0b~

i-

25.4
(1.00)
MIN

~

91-1 e~
--L
$)

.l(

TG>

T

7mm

10mm

14mm

20mm

VOLTAGE
MODEL

MIN

MAX

MIN

MAX

MIN

MAX

MIN

MAX

VI30LAV320LA

7.5
(0.295)

12
(0.472)

10
(0.394)

16
(0.630)

13.5
(0.531)

20
(0.787)

17.5
(0.689)

(1.043)

10
(0.394)

17
(0.689)

13.5
(0.531)

20.5
(0.807)

17.5
(0.689)

28
(1.102)

V420LAVIOOOLA

26.5

0D

All

7.5
(0.295)

9
(0.354)

10
(0.394)

12.5
(0.492)

13.5
(0.531)

17
(0.669)

17.5
(0.689)

23
(0.906)

e

All

4
(0.157)

6
(0.236)

6.5
(0.256)

8.5
(0.335)

6.5
(0.256)

8.5
(0.335)

6.5
(0.256)
(Note 1)

8.5
(0.335)
(Note 1)

V130LAV320LA

1.5
(0.059)

3.5
(0.138)

1.5
(0.059)

3.5
(0.138)

1.5
(0.059)

3.5
(0.138)

1.5
(0.059)

3.5
(0.138)

2.5
(0.098)

5.5
(0.217)

2.5
(0.098)

5.5
(0.217)

2.5
(0.098)

5.5
(0.217)

(Note 1)
el

E

V420LAVl000LA
E

V130LAV320LA

5.6
(0.220)

5.6
(0.220)

5.6
(0.220)

5.6
(0.220)

V68ZAVl00ZA

7.3
(0.287)

7.3
(0.287)

7.3
(0.287)

7.3
(0.287)

10.8
(0.425)

10.8
(0.425)

0.86
(0.034)

0.76
0.86
(0.030) (0.034)
(Note 1) (Note 1)

VIOOLA
0b
(Note 2)

All

0.585
(0.023)

0.685
(0.027)

0.76
(0.030)

0.86
(0.034)

0.76
(0.030)

NOTE: Dimensions in millimeters, inches in parentheses.
1. 10mm ALSO AVAILABLE; See Ordering Information.

2. 1000V parts only supplied with lead wire of diameter 1.00 ± 0.05 (0.039 ± 0.002).

9-65

0::1/)

01-

U
I1/)::;:)
-0
0::0

~g:

LA Series
Available Lead Style

"Tn

Radial lead types can be supplied with a preformed crimp in
the leads, and are available in all model sizes. lead trim
(lTRIM) is supplied to the dimensions shown.

I
.~-L

·SEATING
PLANE

TLTRIM
·Seating plane interpretation per IEC-717
CRIMPED AND TRIMMED LEAD

VARISTOR MODEL SIZE
7mm
SYMBOL
A
LTRIM

10mm

14mm

MIN

MAX

-

15
(0.591)

-

19.5
(0.768)

2.41
(0.095)

4.69
(0.185)

2.41
(0.095)

4.69
(0.185)

MIN

MAX

-

MIN

-

20mm
MAX

-

22.5
(0.886)

2.41
(0.095)

4.69
(0.185)

MIN

-

MAX

-

29.0
(1.142)

2.41
(0.095)

4.69
(0.185)

..

NOTE: Dimensions In millimeters, Inches In parentheses .

Ordering Information
• For crimped and trimmed lead styles, standard radial type
model numbers are changed by replacing the model letter
"A" with "C".

• For 10/±1mm lead spacing on 20mm diameter models
only; append standard model numbers by adding ·X10".

Example:

Example:

STANDARD CATALOG
MODEL

ORDER AS:

STANDARD CATALOG
MODEL

ORDER AS:

V130LA2

V130LC2

V130LA20A

V130LA20AX10

• For crimped leads without trimming and any variations to
the above, contact Harris Semiconductor Power Marketing.

9-66

MA Series

HARRIS
SEMICONDUCTOR

Axial Lead Metal-Oxide Varistors

August 1993

Features
• 3mm Diameter Disc Size
• Wide Operating Voltage Range VM(AC)RMS ••••••••••••• 9V to 264V
• Available In Tape and Reel Packaging for Use With Automatic
Insertion Equipment

MA SERIES

Description
MA series transient surge suppressors are axial· lead metaloxide varistors for use in a wide variety of industrial and
commercial electronic equipment. The construction of these

Absolute Maximum Ratings

3mm diameter disc-type axial lead varistors make them particularly useful in automatic insertion equipment.

For ratings of individual members of a series, see Device Ratings and Characteristics chart

Continuous:
Steady State Applied Voltage:
AC Voltage Range (VM(AC)RMS) ................................................... .
DC Voltage Range (V M(DC» ..................................................... .

MASERIES

UNITS

9t0264
13 to 365

V
V

40 to 100

A

Transient:
Peak Pulse Current (I TM )
For 81201J.S Current Wave (See Figure 2) ........................................... .
Single Pulse Energy Range
For 10/1 OOOIJ.S Current Wave (WTM ) ............................................... .

0.06 to 1.7

J

a: en

Operating Ambient Temperature Range (TA) .......................................... .

-55 to +85

°C

I-()

Storage Temperature Range (TSTG) ................................................. .

-55 to +125

°C

Temperature Coefficient (aV) of Clamping Voltage (V c ) at Specified Test Current ............. .

<0.01

%I"C

Hi-Pot Encapsulation (Isolation Voltage Capability) ..................................... .
(Dielectric must withstand indicated DC voltage for one minute per MIL-STD 202, Method 301)

1000

V

Insulation Resistance ............................................................ .

1000

MQ

Copyright © Harris Corporation 1993

File Number
9-67

01-

en::!
-0
a:O

2191.2

:!g:

Specifications MA Series
Device Ratings and Characteristics
CHARACTERISTICS (+25°C)

MAXIMUM RATINGS (+85°C)
CONTINUOUS

TRANSIENT

MAX CLAMPING
VOLT ATlp
VALUE CURRENT
(8120I1s)

TYPICAL
CAPAC!TANCE

MAX

Ip =2.0A

f=1MHz

(V)

(V)

(pF)

18
18
18

23
21
21

49
44
49

550
550
550

16
19
19

22
22
22

28
26
26

55
51
55

410
410
410

40
40
40

21
24
24

27
27
27

34
31
31

67
59
67

370
370
370

0.13
0.15
0.14

40
40
40

26
29.5
29.5

33
33
33

40
36.5
36.5

73
67
73

300
300
300

28
31
31

0.16
0.18
0.17

40
40
40

31
35
35

39
39
39

47
43
43

86
79
86

250
250
250

27
30
30

34
38
38

0.19
0.21
0.19

40
40
40

37
42
42

47
47
47

57
52
52

99
90
99

210
210
210

56A
56B
56S

32
35
35

40
45
45

0.23
0.25
0.23

40
40
40

44
50
50

56
56
56

68
62
62

117
108
117

180
180
180

V68MA3A
V68MA3B
V68MA3S

68A
68B
68S

38
40
40

48
56
56

0.26
0.30
0.27

40
40
40

54
61
61

68
68
68

82
75
75

138
127
138

150
150
150

V82MA3A
V82MA3B
V82MA3S

82A
82B
82S

45
50
50

60
66
66

0.33
0.37
0.34

40
40
40

65
73
73

82
82
82

99
91
91

163
150
163

120
120
120

Vl00MMA
Vl00MA4B
Vl00MMS

100
101
102

57
60
60

72
81
81

0.40
0.45
0.42

40
40
40

80

90
90

100
100
100

120
110
110

200
185
200

100
100
100

V120MA1A
V120MA2B
V120MA2S

120
121
122

72
75
75

97
101
101

0.40
0.50
0.46

100
100
100

102
108
108

120
120
120

138
132
132

220
205
220

40
40
40

V150MA1A
V150MA2B

150
151

88
92

121
127

0.50
0.60

100
100

127
135

150
150

173
165

255
240

32
32

V180MA1A
V180MA3B

180
181

105
110

144
152

0.60
0.70

100
100

153
162

180
180

207
198

310
290

27
27

V220MA2A
V220MMB

220
221

132
138

181
191

0.80
0.90

100
100

187
198

220
220

253
242

380
360

21
21

V270MA2A
V270MA4B

270
271

163
171

224
235

0.90
1.00

100
100

229
243

270
270

311
297

460
440

17
17

V330MA2A
V330MA5B

330
331

188
200

257
274

1.00
1.10

100
100

280
297

330
330

380
363

570
540

14
14

V390MA3A
V390MA6B

390
391

234
242

322
334

1.20
1.30

100
100

331
351

390
390

449
429

670

640

12
12

V430MA3A
V430MA7B

430
431

253
264

349
365

1.50
1.70

100
100

365
387

430
430

495
473

740
700

11
11

RMS
VOLTAGE

DC
VOLTAGE

ENERGY

DEVICE
MARKING

VM(AC)

VM(DC)

WTM

tru

MIN

VN(DC)

(V)

(V)

(J)

(A)

(V)

(V)

V18MA1A
V18MA1B
V18MA1S

18A
18B
18S

9
10
10

13
14
14

0.06
0.Q7
0.06

40
40
40

14
15
15

V22MA1A
V22MA1B
V22MA1S

22A
22B
22S

10
14
14

15
18
18

0.09
0.09

40
40
40

V27MA1A
V27MA1B
V27MA1S

27A
27B
27S

13
17
17

19
22
22

0.10
0.11
0.10

V33MA1A
V33MA1B
V33MA1S

33A
33B
33S

18
20
20

23
26
26

V39MA2A
V39MA2B
V39MA2S

39A
39B
39S

22
25
25

V47MA2A
V47MA2B
V47MA2S

47A
47B
47S

V56MA2A
V56MA2B
V56MA2S

MODEL
NUMBER

(101
1oo011s)

b.l0

PEAK
CURRENT
(8/20I1s)

NOTE: Average power diSSipation of transients not to exceed 200mW.

9-68

VARISTOR VOLTAGE AT
1mA DC TEST
CURRENT

MA Series
Power Dissipation Requirements
Transients in a suppressor generate heat too quickly for it to
be transferred to the surroundings during the pulse interval.
Continuous power dissipation capability, therefore, is not a
necessary design requirement for a suppressor, unless transients occur in rapid succession. Under this condition, the
average power dissipation required is simply the energy
(watt-seconds) per pulse times the number of pulses per
second. The power so developed must be within the specifications shown on the Device Ratings and Characteristics
table for the specific device. Furthermore, the operating values need to be derated at high temperatures as shown in
Figure 1. Because varistors can only dissipate a relatively
small amount of average power they are, therefore, not suitable for repetitive applications that involve substantial
amounts of average power dissipation.

100

\

w 90
::>

..J

~
c
w
!;(

I\.

80

\

70

a: 60

\

u.
0 50
40

\

!zw

\

0

a: 30
w
II. 20

\

10

o .-55

\
50

60

70 80 90 100 110 120 130 140 150
AMBIENT TEMPERATURE (OC)

FIGURE 1. CURRENT, ENERGY AND POWER DERATING
CURVE

w
3100

~

0 1 = Virtual Origin of Wave
T =Time From 10% to 90% 01 Peak
T1 =Virtual Front Time =1.25 • t
T2 =Virtual Time to Half Value (Impulse Duration)
Example: For an 8120115 Current Waveform:
8llS =T1 =Virtual Front Time
20llS =T2 =Virtual Time to Half Value

~ 90
w

II.
U.

o

!zw

50

o

a:
w

II.

TIME

FIGURE 2.

PEAK PULSE CURRENT TEST WAVEFORM

Transient V-I Characteristics Curves
800
600
~

>

400

MAX CLAMPING VOLTAGE
DISC SIZE 3mm
18 TO 100VNWC~ RATING
TA = _55°C T + soC

;; 300

~

~ 200

~

1S0

~ 100

§l
~
:i!

80

(/

-

V82MA3A1S
V68MA3A1S
VS6MA2A1~

~2,OOO

f

t;::..:,.;

",1,500

:J~./'

t/.::I

II

-

t::::

30

-

~
II.

:i!

§l
~

.:3 ~7MA2A1S
V39MA2A1S

100
PEAK AMPERES (A)

V330MA2A
V270MA2A
V220MA2A

~
~

400

~~

200

I-- ~

:i!

V33MA1A1S
V27MA1A1S

I

~I'~"W'
/

800
600

~I--'

:::::"1--'
~I--'

1\\

V180MA1A
V150MA1A
V120MA1A1S

'V1~~~1~~~S
10.1

I 11111111
V430MA3A

11/

~ 1,000

~

'\ 0

MAX CLAMPING VOLTAGE
DISC SIZE 3mm
120 TO 430VN(DC~ RATING
TA = -SSoc TO +8 °c

~

~~

...60
40

4,000

V100MA4A1S

10.1

101

FIGURE 3. CLAMPING VOLTAGE FORV18MA1A1S - V100MMAIS

9-69

100
PEAK AMPERES (A)

10 1

FIGURE 4. CLAMPING VOLTAGE FOR V120MA1A1SV430MA3A

a: en

oJJ-U
en::;)
-0

a:O

~g:

MA Series
Transient V-I Characteristics Curves (Continued)
600
500 _ MAX CLAMPING VOLTAGE
DISC SIZE 3mm
400
18 TO 1OOVNg>C RATING
~300 _ TA=·55 0 CT + 5°C

h

~~

~

~ 200

g

~

~

~
:;

;8 -

60
~ 50
:; 40

30 -

:.-

:::: ....

-

.....

:.-

-

w 100

I-

f-

......

~

f-

4,000

11111

I III

3,000

Vl00MA4B
V82MA3B
V68MA3B

~2,OOO

1111111

~

MAXIMUM CLAMPING VOLTAGE
DISC SIZE 3mm
120 TO 430VN(DC~ RATING
TA = ·55 0 C TO +8 °C

U)

!:i

~

V430MA7B
V390MA6B
V330MA5B
V270MA4B
V220MA4B
V180MA3B
V150MA2B
V120MA2B

g 1,000
~

ijgg
lSg

::>
:;

500
400
300

~

~~

~

~ V47MA2B
V56MA2B

~

\"'
V39MA2B
"
V33MA1B
V27MA1B
V22MA1B
V18MA1B

r--

200

FIGURE 5. CLAMPING VOLTAGE FOR V18MA1B· V100MA4B

-

r--

100
10.3

10.1
100
10 1
PEAK AMPERES (A)

10.2

i--'
i--'

10.1
100
10'
PEAK AMPERES (A)

102

103

FIGURE 6. CLAMPING VOLTAGE FOR V120MA2B· V430MA7B

Pulse Rating Curves

50

100

~

DISC SIZE 3mm
I II V18MA1A· Vl00MA4B

20 -..t.1

g
lZ

w

a:
a:

::>
()

10

S
2

w

Cl

~

111.11

I'-....

105
106

102

g
IZ
W

103

~4'

r--......

/""

N 1'">. .

:--- ......

a:

::>
U)

50
20
10

a:
a:

I'-..

~ ~t.....

()

w

2

a:

1

Cl

::>
U)

0.5

0.5
INDEFINITE

0.2

Ll III

0.1
20

100

--- r-.

r---.. . . ........ i""

r::::: ~

1,000
IMPULSE DURATION (~s)

~1;-

..1~
.......

::>

lf--

FIGURE 7. SURGE CURRENT RATING CURVES FORV18MA
SERIES· Vl00MA SERIES

20

03

04

105
106

.... 7'
~ ~r-.
~

."tll""1!
II III

0.1
10,000

V,

l'-,.
7~

,

0.2

I=::t:-

DISC SIZE 3mm
V120MA1A· V430MA7B

k.2~

100

r--

t-....
~,

="1'

r-:::::s:::
~
--...;:

~~

1,000
IMPULSE DURATION (fts)

10,000

FIGURE 8. SURGE CURRENT RATING CURVES FORV120MA
SERIES· V430MA SERIES

NOTE: If pulse ratings are exceeded, a shift of VN(DC) (at specified current) of more than ±1 0% could result. This type of shift, which normally
results in a decrease of V N(DC), may result in the device not meeting the original published specifications, but it does not prevent the
device from continuing to function, and to provide ample protection.

9·70

MA Series
Packaging

Tape and Reel Specification
H1 = H2 1 0.040

to:l~l-J,
"'
Ir-H1~ 0.098- ~H2-iI - -JI---to:l
..I.....

0.1350.145

-

t-

r

0.177

n~

--

t'L

T -- ---

INCHES
SYMBOL

MIN

[

MILLIMETERS

MAX

MIN

MAX

0.020.023

0.200
10.020
[

0b

0.024

0.026

0.61

0.66

0D

0.135

0.177

3.43

4.5

G

0.098

0.177

3.43

4.5

H

0.118

0.236

3.0

6.0

L

1.130

1.220

28.70

31.0

~.

I.

~-.i

I.

[

Typical Weight

/~

0.240 1 E
110.040

=25g

E

2.062
±0.059
2.681
MAX

~"-

.. I 0.240
±0.040r
..

Tape And Reel Data
• Conforms to EIA Standard RS-296E

Ordering Information
• Standard model numbers are changed by replacing the
modelleter "A" with "T'.
Example:
STD. CAT. MODEL

ORDER AS
0:: 00

V18MAIA

01-

V18MTtA

I- U
00::::1

-0

Quantity Per Reel: 5,000

0::0

~~

9-71

ML Series
Multilayer Transient
Surface Mount Surge Suppressors

August 1993

Features
• Leadless Chip Form - Zero Lead Inductance
• Multilayer Surface Mount Surge Suppressor
• +12SoC Continuous Operating Temperature
• Available In Tape and Reel for Automatic Pick and Place

• Wide Operating Voltage Range VM(DC) •••••••••• 3.SV to 6aV
MLSERIES

• Broad Range of Energy Handling Capabilities
• Low Profile, Compact Chip Size
• Inherently BI-directional
• No Plastic or Epoxy Packaging Guarantees Better than 94V-O
flammability Rating

Description
ML series transient surge suppressors are designed to
protect sensitive electronic devices from destruction by high
voltage transients. These suppressors are designed to fail
short when overstressed and protect the associated
equipment. The ML suppressor is manufactured from
semiconducting ceramics which offer rugged protection,
excellent transient energy absorption and increased internal
heat dissipation.

The devices are in chip form, eliminating lead inductance
and guaranteeing the fastest speed of response to transient
surges. These transient suppression devices have significantly smaller footprints and lower profiles than traditional
TVS diodes or radial MOV's (metal oxide varistors), thus
allowing designers to reduce size and weight while increas'
ing system reliability.

Absolute Maximum Ratings For Ratings of Individual members of a series, see device ratings and Characteristics chart
MLSERIES

UNITS

Continuous:
Steady State Applied Voltage:
DC Voltage Range (VM(OC» .••••••••••• " •..••.••.••..••• , .•.••••••.•.....••..••.
AC Voltage Range (VM(AC)RMS) ••..•.•••••..•••••••••••••••••••.••..•••••••.•••••••

3.5 to 68
2.5 to 50

V
V

Transient:
Non-Repetitive Surge Current, 8120 JlS Waveform, (ITM) ••••.•..•••••••••.•.....••...••.
Non-Repetitive Surge Energy, 10/1000 JlS Waveform, (WTM) •••.••..•••.•••••••..•...••.

100 to 250
0.3 to 1.2

A

Operating Ambient Temperature Range (TA) .......................................... .

-55 to +125

°C

Storage Temperature Range (TSTG)' •••.•••..•••••••••••••••••.••••.••.••••...•.•..•.

-55 to +150

°C

Temperature Coelficient(aV) of Clamping Voltage (Vel at Specified Test Current. •.....•......

<0.01

o/oI"C

CAUTION: These devices are sensitive to electrostatic discharge. Users should follow proper I.C. Handling Procedures.
Copyright © Harris Corporation 1993

9-72

J

File Number

2461.3

Specifications ML Series
Device Ratings and Characteristics
MAXIMUM RATINGS (+125°C)
MAXIMUM
MAXIMUM
NON·
NON·
REPETITIVE REPETITIVE
SURGE
SURGE
CURRENT
ENERGY

MAXIMUM
CONTINUOUS
WORKING
VOLTAGE

(8/20~s)

(10/1000~s)

CHARACTERISTICS (+25 OC)
MAXIMUM
CLAMPING
VOLTAGE
AT 10AMP
(8120~s)

NOMINAL VOLTAGE
AT 1mA DC TEST
CURRENT

TYPICAL
CAPACITANCE
1= 1MHz

VM(DC)

VM(AC)

ITM

WTM

Vc

VN(DC) MIN

VN(DC) MAX

(V)

(V)

(A)

(J)

(V)

(V)

(V)

(pF)

V3.5MLA1206

3.5

2.5

100

0.3

14

5.0

7.0

6000

V5.5MLA1206

5.5

4

150

0.4

15.5

7.1

8.7

4500

V14MLA1206

14

10

150

0.4

30

16.4

20

2100

V18MLA1206
V18MLA1210

18
18

14
14

150
250

0.4
0.8

40
40

22
22

27
27

1700
1900

V26MLA1206
V26MLA1210

26
26

20
20

150
250

0.6
1.2

56
54

29.5
29.5

38.5
38.5

800
1000

V33MLA1206

33

26

180

0.8

72

38

45

500

V42MLA1206

42

30

180

0.8

86

46

56

450

V56MLA1206

56

40

180

1.0

110

61

76

350

V68MLA1206

68

50

180

1.0

130

76

90

150

MODEL
NUMBER

NOTES:
1. Typical leakage at +25°C < 50~A, maximum leakage 100~.
2. Average power dissipation of transients for 1206 and 1210 sizes not to exceed 0.10W and 0.15W, respectively.
3. Devices specifically for automotive application also available.

Power Dissipation Requirements

A

Transients in a suppressor may generate heat too quickly for
it to be transferred to the surroundings during the pulse
interval. Continuous power dissipation capability, therefore is
not a necessary requirement for a suppressor, unless
transients occur in rapid succession. Under this condition,
the average power dissipation required is simply the energy
(walt·seconds) per pulse times the number of pulses per
second. The power so developed must be within the specifi·
cations shown on the Device Ratings and Characteristics
table for the specific device. Furthermore, the operating
values need to be derated at high temperatures as shown in
Figure 1.

w

~

..J

90

~

80

0

w

70

a:

60

!;;:
u..

50

0-

40

0

z

w

(.)

30

...w

20

a:

,,

100

,

1\
\

1\
\

10

O~
-55

a:

,
50

60

70

80

90 100 110 120 130 140 150

AMBIENT TEMPERATURE (oC)

FIGURE 1. CURRENT, ENERGY AND POWER DERATING
CURVE
w

~
"w"
...
~

100 •••••••.•••••••••••••••••
90 .................... .
01

50

!z
~

a:

...w

10 •••

.... !...... !..............
i i

II

I

= VIRTUAL ORIGIN OF WAVE
= TIME FROM 10% TO 90% OF PEAK

=

=

11 VIRTUAL FRONT TIME 1.25 x I
12 = VIRTUAL TIME TO HALF VALUE
(IMPULSE DURATION)

TIME

FIGURE 2. PEAK PULSE CURRENT TEST WAVEFORM

9·73

EXAMPLE:
FOR AN 8120flS CURRENT
WAVEFORM:
8~s = 11 = VIRTUAL FRONT
TIME
20flS 12 VIRTUAL TIME TO
HALF VALUE

= =

I/)

011-°
1/);:)
-0

a:O

~g:

ML Series
Maximum Transient V-I Characteristic Curves
100

"''''''

MAXIMUM LEAKAGE

~

~

w

W

~

!j

~

CI

~
:.:

«w

"":::E

::>

rmlU011111I

V14MLA1206
10
V5.SMLA1206

::>

:::E

~

:::E

""". """. ""''' """.

MAXIMUM CLAMPING VOLTAGE

V42MLA1206
V33MLA120S

:::E

~

rV,u3Ul.SIJJIIM'-LAW1.lU2JJJ106"'f11IH1l1f--HttHll-+ MAXIMUM CLAMPING VOLTAGE
HHItIIIl-HittItIt-H1IH111t-+ttHIIII--+ 3.S TO 14VM(DC) RATING

P

MAXIMUM CLAMPING VOLTAGE
18 TO 42VM(DC) RATING

V26MLA120SI"

TA = -SSOC TO +12SoC

TA = -55 0 C TO +12SoC

VlSMLA120SI"

10':-U~~~~WLLlli~Uill~~~uw~uw~~~

100~A

1mA 10mA 100mA lA

lOA

1~

100A

10~ 100~A

CURRENT

V2~~,TA 1~:,~

MAXIMUM CLAMPING VOLTAGE
56 TO SSVM(DC) RATING
TA = -SSoC TO +12S'C

10LW~~~7ll~~~~~~~~~~~~~

1mA 10mA 100mA 1A

100A

FIGURE 4. V18MLA1206 TO V42MLA1206 MAXIMUM V-I
CHARACTERISTIC CURVES

~~:IM~~II~E~~G~

10~A 100~

lOA

CURRENT

FIGURE 3. V3.5MLA1206 TO V14MLA1206 MAXIMUM V-I
CHARACTERISTIC CURVES

I-tHtllllH-litllllH-litllll-ttHllt+H

1mA 10mA 100mA 1A

lOA 100A

CURRENT

10

111~~8IJ~~210
l~A

10~A 100~A

I ~:XI~~I~ ~~~~p:~I~·V~~~:G~1

MAXIMUM CLAMPING VOLTAGE
18 TO 26VM(DC) RATING
TA = -5SoC TO +12SoC
1mA 10mA 100mA 1A

10A 100A

CURRENT

FIGURE 5. V56MLA 1206 TO V68MLA 1206 MAXIMUM V-I
CHARACTERISTIC CURVE

FIGURE 6. V18MLA1210 TO V26MLA1210 MAXIMUM V-I
CHARACTERISTIC CURVES

9-74

ML Series
Device Characteristics

Speed of Response

At low current levels, the V-I curve of the multilayer transient
voltage suppressor approaches a linear (ohmic) relationship
and shows a temperature dependent affect (Figure 7). The
suppressor is in a high resistance mode (approaching 109
ohms) and appears as a near open circuit. This is equivalent
to the leakage region in a traditional zener diode. leakage
currents at maximum rated voltage are in the microamp
range and in most cases below 50~A.
When clamping transients at higher currents, at and above
the 10J.1A range, the multilayer suppressor approaches a
1-10n characteristic. Here, the multilayer becomes virtually
temperature independent (Figure 8).

Traditional transient suppressors, e.g. metal oxide varistors
and zener diode type devices, have finite lead inductance,
device capacitance and resistance. Thus these suppressors
have their response times limited (slowed) by parasitic lead
impedances. These difficulties have been recognized by the
IEEE committees on transient suppressors concluding that
response time of a suppressor is influenced by lead
configuration and length. Unlike the leaded packages offered
for surface mounting (Gull-wing and J-bend) the multilayer
suppressor is a true surface mount device. As the multilayer
has no leads it therefore has virtually zero inductance and
the major factor controlling response time is eliminated.

100
u.
0

80

~l

60

~~

50

....

tro

-z'"
....
w<
~~

~

/ /V/

tr

::I
0

~~

1E
~

II/}

JV /

o~

>

Z

"V/ 1/'/

40

!:i ....

~

...- ......

V/

II

JI IV/

30

I

/ V J II
II ~/sOY75

20

;'00 /125 0 C

10.7

10-6

10.5

10-4

VARISTOR CURRENT (A DC)

FIGURE 7. TYPICAL TEMPERATURE DEPENDENCE OF THE CHARACTERISTIC CURVE IN THE LEAKAGE REGION

0: 00

100

01-

CLAMPING VOLTAGE (VOLTS)

I- U
00;:)

-0

0:0

;;g:

~26MLA1206 -

V5.5MLA1206

10
-60

-40

-20

20

40

60

80

100

120

140

TEMPERATURE fC)

FIGURE 8. CLAMPING VOLTAGE OVER TEMPERATURE (Vc AT 10AMPS)

9-75

ML Series
Energy Absorption/Peak Current Capability
This rating serves as a figure of merit for the ML suppressor.
Energy is calculated by multiplying the clamping voltage,
transient current and transient duration. An important
advantage of the multilayer TVS interdigitated construction is
its mass of transient suppressor material available to absorb
energy. As a result. the peak· temperature per energy
absorbed is very low. The matrix of semiconducting grains
combine to absorb and distribute transient energy (heat)
(Figure 9). This dramatically reduces peak temperature,
thermal stresses and enhances device reliability.

As a measure of the device capability in energy handling and
peak current. the V26MLA1206A23 part was tested with
multiple pulses at its peak current rating (150A, 8/20 microseconds). As this level of current is far in excess of anything
the device is exposed to in an Ie protection application it is
taken as measure of the ruggedness and inherent capability.
At the end of the test. 10.000 pulses later, the device voltage
characteristics are still well within specification (Figure 10).

FIGURE 9. MULTILA YER TVS INTERNAL CONSTRUCTION

=

PEAK CURRENT 150A
100 8120ms DURATION, 30 SECS BETWEEN PULSES

V26MLA1206

10

o

2000

4000

6000

8000

NUMBER OF PULSES

FIGURE 10. REPETITIVE PULSE CAPABILITY

9-76

10000

12000

ML Series
Soldering Recommendations

Recommended Pad Outline

The principal techniques used for the soldering of
components in surface mount technology are Infra Red (IR)
Reflow. Vapour Phase Reflow and Wave Soldering. When
wave soldering. the ML suppressor is attached to the substrate by means of an adhesive. The assembly is then
placed on a conveyor and run through the soldering process.
With IR and Vapour Phase reflow the device is placed in a
solder paste on the substrate. As the solder paste is heated
it reflows. and solders the unit to the board.

I~

I
1
B

oE-.----

f. 1

With the ML suppressor. the recommended solder is a 62/
36/2 (Sn/Pb/Ag) silver solder paste. While this configuration
is best. a 60/40 (Sn/Pb) or a 63/37 (Sn/Pb) solder paste can

NOTE 1: Avoid metal runs in this area.

also be used. In soldering applications. the ML suppressor is
held at elevated temperatures for a relatively long period of
time. With the wave soldering operation is the most
strenuous of the processes. To avoid the possibility of
generating stresses due to thermal shock. a preheat stage in
the soldering process is recommended. and the peak temperature of the solder process should be rigidly controlled.

CHIP SIZE

SOLDERING
OPERATION

IR Reflow

TIME
(SECONDS)

PEAK
TEMPERATURE (OC)

5 - 10

220

Vapour Phase Reflow

5 - 10

222

Wave Solder

3-5

260

1206

1210

When using a reflow process. care should be taken to
ensure that the ML chip is not subjected to a thermal
gradient steeper than 4 degrees per second; the ideal
gradient being 2 degrees per second. During the soldering
process. preheating to within 100 degrees of the solders
peak temperature is essential to minimize thermal shock.
Examples of the soldering conditions for the ML series of
suppressors are given in the table below.
Once the soldering process has been completed. it is still
necessary to ensure that any further thermal shocks are
avoided. One possible cause of thermal shock is hot printed
circuit boards being removed from the solder process and
subjected to cleaning solvents at room temperature. The
boards must be allowed to cool to less than 50 degree
celsius before cleaning.

A - - - -...~~I

SYMBOL

IN

MM

IN

MM

A

0.219

5.53

0.203

5.15

B

0.147

3.73

0.103

2.62

C

0.073

1.85

0.065

1.65

Soldering Recommendations
Material- 62136/2 Sn/Pb/Ag or equivalent
Temperature - 230°C. 5 seconds max
Flux - nonactivated

Dimensional Outline

a:(/)
O~
~C)
(/)::::1

-0
a:O

~g:

CHIP SIZE

1210

9-77

1206

SYMBOL

INCHES

mm

INCHES

mm

o Max.

0.113

2.87

0.071

1.80

E

0.02
±0.01

0.50
±0.25

0.02
±0.01

0.50
±0.25

L

0.125
±0.012

3.20
±0.30

0.125
±0.012

3.20
±0.30

W

0.10
±0.012

2.54
±0.30

0.06
±0.011

1.60
±O.28

Specifications ML Series
Tape and Reel Specifications
• Conforms to EIA • 481, Revision A
• Can be Supplied to IEC Publication 286 . 3
SYMBOL

MILLIMETERS

DESCRIPTION
Width of Cavity

Dependent on Chip Size to Minimize Rotation.

Bo

Length of Cavity

Dependent on Chip Size to Minimize Rotation.

Ko

Depth of Cavity

Dependent on Chip Size to Minimize Rotation.

W

Width of Tape

F

Distance Between Drive Hole Centers and Cavity Centers

3.5± 0.5
1.75 ± 0.1

Ao

B±0.2

E

Distance Between Drive Hole Centers and Tape Edge

P1

Distance Between Cavity Center

4±0.1

P2

Axial Distance Between Drive Hole Centers and Cavity Centers

2 ±0.1

Po

Axial Distance Between Drive Hole Centers

Do

Drive Hole Diameter

1.55 ± 0.05

D1

Diameter of Cavity Piercing

1.05 ± 0.05

t1

Embossed Tape Thickness

0.3 max

t2

Top Tape Thickness

0.1 max

4±0.1

NOTE: Dimensions in millimeters.

Standard Packaging
The ML Series of transient suppressors are always shipped
in tape and reel. The standard 330 millimeter (13 inch) reel
utilized contains 8000 pieces for the 1210 and 10000 pieces
for the 1206 chip. To order add "T23" to the standard part
number, e.g. V5.5MLA 1206T23 or V68MLA1206T23.

Special Packaging
Option 1: 178 millimeter (7 inch) reels containing 2000 or
2500, depending on chip size, pieces are
available. To order add "H23" to the standard part
number,
e.g.
V5.5MLA1206H23
or
V68MLA 1206H23.
Option 2: For small sample quantities (less than 100 pieces)
the units are shipped bulk pack. To order add
"A23" to the standard part number, e.g.
V5.5MLA1206A23 or V6BMLA1206A23.

9-78

178MM
OR 330MM

CIA. REEL

ML Series
Terms and Descriptions
Rated DC Voltage (VM(DC)

leakage (IJ at Rated DC Voltage

This is the maximum continuous DC voltage which may be
applied up to the maximum operating temperature of the
device. The rated DC operating voltage (working voltage) is
also used as the reference point for leakage current. This
voltage is always less than the breakdown voltage of the
device. Unlike the zener diode all multilayer TVS devices
have a maximum leakage current of less than 100!!A.

In the non-conducting mode, the device is at a very high
impedance (approaching 1090) and appears as an almost
open circuit in the system. The leakage current drawn at this
level is very low «50IlA at ambient temperature) and, unlike
the zener diode, the multilayer TVS has the added advantage that, when operated up to its maximum temperature, its
leakage current will not increase above 5001lA.

Rated AC Voltage (VM(AC)RMS)

Nominal Voltage (VN(DC)

This is the maximum continuous sinusoidal rms voltage
which may be applied. This voltage may be applied at any
temperature up to the maximum operating temperature of
the device.

This is the voltage at which the device changes from the off
state to the on state and enters its conduction mode of operation. The voltage is usually characterized at the 1mA point
and has a specified minimum and maximum voltage listed.

Maximum Non-Repetitive Surge Current (lTM)

Clamping Voltage (Vel

This is the maximum peak current which may be applied for
an 8/201lS impulse, with rated line voltage also applied, without causing device failure. The pulse can be applied to the
device in either polarity with the same confidence factor. See
Figure 2 for waveform description.

This is the peak voltage appearing across the suppressor
when measured at conditions of specified pulse current and
specified waveform (8/20IlS). It is important to note that the
peak current and peak voltage may not necessarily be coincidental in time.

Maximum Non-Repetitive Surge Energy (WTM)

Capacitance (C)

This is the maximum rated transient energy which may be
dissipated for a single current pulse at a specified impulse
duration (10/lOOOIlS), with the rated DC or RMS voltage
applied, without causing device failure.

This is the capacitance of the device at a specified frequency
(lMHz) and bias (Wp_p).

a:CI)

011-0
C1):::l
-0

a:o

~lf

9-79

NA Series
Industrial High Energy Metal-Oxide
Square Varistors

August 1993

Features
• Provided Unpackaged For Unique Packaging By Customer
• Solderable Electrode Finish Also Provides Pressure Contacts for
Stacking Applications
• Wide Operating Voltage Range VM(AC)RMS , •••.•.•.•. 130V to 750V
• Peak Pulse Current Capability ITM' ••.••••••••••.•••••••• 40,OOOA
• High Energy Capability WTM ••••••••••.••••••••••• 270J to 1050J
NASERIES

Description
NA series transient surge suppressors are industrial high·
energy square varistors intended for special applications
requiring unique contact or packaging considerations. The
electrode finish of these devices is solderable and can also
be used as pressure contacts for stacking applications.

These NA series industrial square varistor is available as a
34mm device, with thicknesses ranging from 1.8mm mini·
mum for the 130V device to 8.3mm maximum for the 750V
device. For information on mounting considerations refer to
Application Note AN8820.

Absolute Maximum Ratings For ratings of individual members of a series, see Device Ratings and Characteristics chart
. Continuous:
Steady State Applied Voltage:
AC Voltage Range (V M(AC)RMS) ..••....•...•..........•.•............•.............
DC Voltage Range (VM(DC») •....•..........•.......••..•.....•...•.•.•.•..•.•....

NA SERIES

UNITS

130 to 750
175 to 970

V
V

40,000

A

Transient:
Peak Pulse Current (I TM )
For 8I20I1S Current Wave (See Figure 2) ••....•..•..•...•••...••.........•.••..•••..
Single Pulse Energy Range
For 1O/t OOOILS Current Wave (WTM ) ...••.•......•.•..•...••...............•........

270 to 1050

J

Operating Ambient Temperature Range (TA) •.••.•..•.••.•...••.•........••...•.•.....•

·55 to +85

°C

Storage Temperature Range (TSTG) ........•..•.•.•••.....•...•.........•...•.•...•.•

·55 to +125

°C

Temperature Coefficient (aV) of Clamping Voltage (Vel at Specified Test Current ............. .

<0.01

o/oI"C

Copyright © Harris Corporation 1993

File Number
9-80

2825.2

Specifications NA Series
Oevice Ratings and Characteristics
CHARACTERISTICS (+25°C)

MAXIMUM RATINGS (+S5°C)
CONTINUOUS

TRANSIENT

RMS
VOLTAGE

DC
VOLTAGE

1000115)

PEAK
CURRENT
(S/20I1S)

VM(AC)

VM(DC)

WTM

ITM

ENERGY

MODEL
NUMBER

SIZE

(101

MAXIMUM
CLAMPING
VOLTAGE
(Vc) AT200A
(SI2Ol1s)

VARISTOR VOLTAGE
AT 1 rnA DC TEST
CURRENT
MIN

VN(DC)

MAX

TYPICAL
CAPACITANCE

f

Vc

=lMHz

(rnrn)

(V)

(V)

(V)

(A)

(V)

(V)

(V)

(V)

(pF)

V131NA34

34

130

175

270

30,000

184

200

22B

345

10,000

V151NA34

34

150

200

300

30,000

212

240

26B

405

B,OOO

V251NA34

34

250

330

370

40,000

354

390

429

650

5,000

V271NA34

34

275

369

400

40,000

389

430

473

730

4,500

V321NA34

34

320

420

460

40,000

462

510

539

830

3,800

V421NA34

34

420

560

600

40,000

610

680

74B

1,130

3,000

V4B1NA34

34

480

640

650

40,000

670

750

825

1,240

2,700

V511NA34

34

510

675

700

40,000

735

820

910

1,350

2,500

V571NA34

34

575

730

no

40,000

805

910

1000

1,480

2,200

V661NA34

34

660

850

900

40,000

940

1050

1160

1,720

2,000

V751NA34

34

750

970

1050

40,000

1080

1200

1320

2,000

1,800

Average power dissipalion of transients not to exceed 2.0W.

Power Dissipation Requirements
Transients in a suppressor generate heat too quickly for it to
be transferred to the surroundings during the pulse interval.
Continuous power dissipation capability, therefore is not a
necessary requirement for a suppressor, unless transients
occur in rapid succession. Under this condition, the average
power dissipation required is simply the energy (wattseconds) per pulse times the number of pulses per second.
The power so developed must be within the specifications
shown on the Device Ratings and Characteristics table for
the specific device.

100
90
~ 80
0
w 70

~

w

:;)

\.
\.

..J

!;;:
a:

60

II.

50

z~
w

40

0

()

30

<>.

20
10

a:
w

0
-55

''-\.
"'50

60

70

80

'-

90 100 110 120 130 140 150

AMBIENT TEMPERATURE (oC)
FIGURE 1. CURRENT, ENERGY AND POWER DERATING
CURVE

9-81

NA Series
w
3100

~
~

~

0 1 = Virtual Origin of Wave
T =Time From 10% to 90% of Peak
T 1 = Virtual Front Time = 1.25 • t
T2 = Virtual Time to Half Value (Impulse Duration)

90

a.

IS

I-

zw

50

Example: For an 8/201J.S Current Waveform:
8~s = T1 = Virtual Front Time
20~s =T2 =Virtual Time to Half Value

o

a:
~
TIME

PEAK PULSE CURRENT TEST WAVEFORM

Transient V-I Characteristics Curve
MAXIMUM CLAMPING VOLTAGE
VARISTOR SIZE 34mm
130 TO 750 VM(AC) RATING

TA = -55 0 C 10 +8So C

f-

~

~V7S1NA34

V661NA34

VSHNA3\\
V481NA34

:1, V571 NA34

Viil~l~r!Y

~

:;...

~
~

:;..-

~

V321NA34
V271NA34
V251NA34
VI51~~4

100

Vl~I~:r10E-3

10E-2

10E-l
1
PEAK AMPERES (A)

10

100

1,000

FIGURE 3. CLAMPING VOLTAGE FOR V131NA34 - V751NA34

Pulse Rating Curves
50,000

N

10,000

~

_5,000
~
1-2,000

~

20,000

z

ll!I,OOO

a:

B
:::>
VI

......

"

N..

03

104

500

~ 200

a:

DISC SIZE 34mm
~ IY251 NA34 - V751 NA34

......

-....;.

~
100

~

105 106

"i"'-.. D't-..

...............

7,....

~~

-r--

~ !-....

50

INIDEIA~lnlll
100

r-...

1,000
IMPULSE DURATION (~s)

10,000

FIGURE 4. SURGE CURRENT RATING CURVES FOR
V251 NA34 - V751 NA34

FIGURE 5. SURGE CURRENT RATING CURVES FOR
V131 NA34 - V751 NA34

NOTE: If pulse ratings are exceeded, a shift of VN(OC) (at specified current) of more than ±1 0% could result. This type of shift, which normally
results in a decrease of VN(OC), may result in the device not meeting the original published specifications, but it does not prevent the
device from continuing to function, and to provide ample protection.

9-82

NA Series
Packaging
OUTLINE DIMENSIONS: MIllimeters

6.3

33.7
±6.7

R 6.S5

±

6.2
THICKNESS - SEE TABLE

NA SERIES VARISTOR THICKNESS
MODEL
NUMBER

INCHES

MILLIMETERS
MIN

MAX

MIN

V131NA34

1.40

2.30

0.055

0.090

V151NA34

1.70

2.80

0.067

0.011

MAX

V251NA34

2.00

2.70

0.079

0.106

V271NA34

2.20

3.00

0.087

0.118

V321NA34

2.60

3.50

0.102

0.138

V421NA34

3.50

4.70

0.138

0.185

V481NA34

3.80

5.20

0.150

0.205

V511NA34

4.20

5.70

0.165

0.225

V571NA34

4.60

6.30

0.181

0.248

V661NA34

5.30

7.20

0.209

0.284

V751NA34

6.10

8.30

0.240

0.327

NOTE: Parts available encapsulated with soldered tabs, to standard design or customer specific requirements.

9·83

o::m

011-0
m::!
-0

0::0

~!t

PA Series

HARRIS
SEMICONDUCTOR

Base Mount Metal-Oxide Varistors

August 1993

Features
• Recognized as "Transient Voltage Surge Suppressors", UL File
#E75961 to Std. 1449
• Recognized as "Transient Voltage Surge Suppressors", CSA File
#LR91788 to Std. C22.2 No. 1-M1981
• Wide Operating Voltage Range VM(AC)RMS ••••••••••• 130V to 660V
PASERIES

• Creep and Strike Distance Capability Meets Rigid NEMA Standards
• Base Mount Construction for Rigid Mounting Applications
• Quick Connect Tab Terminal

Description
PA series transient surge suppressors are base mount
metal·oxide varistors featuring rigid mountdown construction. and are useful in applications which are critical to vibra·
tion.
These UL and CSA recognized varistors are available in a
wide range of operating voltages. from 130V to 660V

VM(AC)RMS. The base-mount package has a quick connect
tab terminal that provides a fast secure lead mount. Meeting
rigid NEMA standards. PA series varistors have a creep and
strike distance capability that minimizes breakdown along
the package surface.

Absolute Maximum Ratings For ratings of individual members of a series. see Device Ratings and Characteristics chart
Continuous:
Steady State Applied Voltage:
AC Voltage Range (VM(AC)RMS) ..................................................•.
DC Voltage Range (VM(DC») ..................................................... .

PASERIES

UNITS

130 to 660
175 to 850

V
V

6500

A

Transient:
Peak Pulse Current (ITM )
For 8I20J.1S Current Wave (See Figure 2) ........................................ , .. .
Single Pulse Energy Range
For 1011 OOOI1S Current Wave (WTM ) ............................................... .

70 to 250

J

Operating Ambient Temperature Range (TA)

·55 to +85

°C

Storage Temperature Range (TSTG) ..•...............................................

-55 to +125

Temperature Coefficient (aV) of Clamping Voltage (Vcl at Specified Test Current ............. .

<0.01

°C
%fC

•••••••••••••••••••••••••••••••••••••••••••

Copyright © Harris Corporation 1993

File Number
9-84

2192.2

PA Series
Device Ratings and Characteristics
Series PA Varistors are listed under UL file #E75961 and under CSA file #LR91788, as a UL recognized component.
MAXIMUM RATINGS (+S5°C)
CONTINUOUS

CHARACTERISTICS (+250 C)

TRANSIENT

MAX CLAMPING
VOLTVcAT
TEST CURRENT

DC
VOLTAGE

ENERGY

MAX

Vc

Ip

(V)

(V)

(J)

(A)

(V)

(V)

(V)

(V)

(A)

(pF)

V130PA20A

130

175

70

6500

184

200

243

360

100

1900

V130PA20C

130

175

70

6500

184

200

220

325

100

1900

V150PA20A

150

200

80

6500

212

240

284

420

100

1600

V150PA20C

150

200

80

6500

212

240

243

360

100

1600

V250PA40A

250

330

130

6500

354

390

453

675

100

1000

V250PA40C

250

330

130

6500

354

390

413

620

100

1000

V275PA40A

275

369

140

6500

389

430

494

740

100

900

V275PA40C

275

369

140

6500

389

430

453

680

100

900

V320PA40A

320

420

160

6500

462

510

565

850

100

750

V320PA40C

320

420

160

6500

462

510

540

800

100

750

V420PA40A

420

560

170

6500

610

680

790

1160

100

600

V420PA40C

420

560

170

6500

610

680

690

1050

100

600

V480PA80A

480

640

180

6500

670

750

860

1280

100

550

V480PA80C

480

640

180

6500

670

750

790

1160

100

550

V510PA80A

510

675

190

6500

735

820

963

1410

100

500

V510PA80C

510

675

190

6500

735

820

860

1280

100

500

V575PA80A

575

730

220

6500

805

910

1050

1560

100

450

V575PA80A

575

730

220

6500

805

910

960

1410

100

450

V660PA100A

660

850

250

6500

940

1050

1210

1820

100

400

V660PA100C

660

850

250

6500

940

1050

1100

1650

100

400

RMS
VOLTAGE
MODEL
NUMBER

(10/
1000J.ls)

PEAK
CURRENT

(S/20J.lS)

VARISTOR VOLTAGE AT 1mA
DC TEST CURRENT
MIN

VM(AC)

(S/20J.lS)

TYPICAL
CAPACITANCE

f= lMHz

•
o::CI)

NOTE: Average power dissipation of transients not to exceed lW.

011-0
CI)::)
-0
0::0

~lf

Power Dissipation Requirements
Transients in a suppressor generate heat too quickly for it to
be transferred to the surroundings during the pulse interval.
Continuous power dissipation capability, therefore, is not a
necessary design requirement for a suppressor, unless transients occur in rapid succession. Under this condition, the
average power dissipation required is simply the energy
(watt-seconds) per pulse times the number of pulses per
second. The power so developed must be within the specifications shown on the Device Ratings and Characteristics
table for the specific device. Furthermore, the operating values need to be derated at high temperatures as shown in
Figure 1. Because varistors can only dissipate a relatively
small amount of average power they are, therefore, not suitable for repetitive applications that involve substantial
amounts of average power dissipation.

9-85

Wl00~~~~~-+-~~--+--t--~-r~~,

3

90~~--~~--~~--~-+--~-+--+-~

~ 80~-r--r--r--r--P~r--+--r--+--+-~

~ 70~-r--r--r--r--+~'r--+--r--+--+-~
~ 6o~~--~~--~-+--~I,~r--+--+--+~

~ 50~~--~~--~-+--~,r+--~-+--+-~
~ 40~-r--r--r--r--+--r-~~--r--+--+-~

~ 30~~--~~--~-+--~-+~,r--+--+--i
w 20~~--~~--~-+--~-+~r--+--+-~
a..

10r--r~r-;--+--+--+--t-~,r-r--r~
o~~~~~~~--~~--~~~~~~

-55

50

60

70

80

90 100 110 120 130 140 150

AMBIENT TEMPERATURE tOC)
FIGURE 1. CURRENT, ENERGY AND POWER DERATING
CURVE

PA Series
w
3100

~

0 1 = Virtual Origin of Wave
T = Time From 10% to 90% of Peak
T1 = Virtual Front Time =1.25 • t
T2 = Virtual Time to Half Value (Impulse Duration)

~ 90
w

I>.

~
zw

... 50

Example: For an 8120~s Current Waveform:
8~ = T 1 = Virtual Front Time
20~ = T2 = Virtual Time to Half Value

(,)

0:

~
TIME

PEAK PULSE CURRENT TEST WAVEFORM

Transient V-I Characteristics Curves
V320PA40A
6,000 r-----------rnrnm-rrml1TrTTlmnn
5,000
~C~~~~~XCLAMPING VOLTAGE ..1...LWUlL...J...wJ..1WL+HtlIHI

6,OOOr-M-AX-IM-U-M-C-LA-M-P-I-NG-VO-L;-r-A-G-E-rrrml1TrTTImmroTITTTIn
5,000 "A" SUFFIX
V660PASOA
4,000 130 TO 660VM(AC~ RATING
V57SPASOA
_ 3,000
TA = ·5S oC TO +S °C
V:1g~:tgtA
<=.
V420PASOA
~ 2,000 H-+H+IIH--Hf

4,000
_ 3,000

<=.
~ 2,000

g

:.:

~

~ l'OO°l-:l=ffilllII=~m
9081-

I>.

I>.

~ ~8°~ijl~i~m

:::;
~
:::;

H-Htttttt--t+ittttHH-Il1ttlt-ti-tt/tll,

~~~Ii~IIIl~II!I~Il~II~~~

1,000
900

~ ~gg

600
500
400 f-:.J-,-lllJ~.!.J1-1ll1!1~+r

300

130 TO 660VM(AC) RATING
TA = -5SoC TO +Ssoc

:::;
~
:::;

g

f--:t-itiffiamllFl17
V130PA20A

600
500 I-ttlttHft::::
400 H-+tttlttt300

200 L......L.1.llLWL.L.llWlll-'-ll
10.3
10.2
10.1
100
10 1
102
PEAK AMPERES (A)

103

200 '-'-'=-=""'-JJ.
10.3
10.2
10.1

10 4

FIGURE 3. CLAMPING VOLTAGE FOR V130PA20A·
V660PA100A

100
10 1
102
PEAK AMPERES (A)

103

104

FIGURE 4. CLAMPING VOLTAGE FORV130PA20C·
V660PA100C

Pulse Rating Curves
10,000
5,000
2,000

1

2

. . . r-.,

r-.,10= f=f=

_1,000
:!. 500

...z

w
0: 200
0:

:::>

100

w

50

(,)

CJ
0:
:::>
VI

r-.

~

20
10

INDEFINIT
E --

,"'"
t-.r-

~~

II
100

5,000
10,000
2,000 .........

I""

:!.

1,000
IMPULSE DURATION (~s)

•

500

'_1,000
Z

,2

/10 2 3
10 4

t-...

~!~11!~11!~~1~01:~5~!'II
v'10 6

~ ~~~~~r-.~~!I~""';!~!!!i~III!I!r-.,~~I!!I!l1II
g
~~C"~.

.....

5
2

~~~gpljI~~l?V~OPA100C
~i,j~lltE~!!!~~~~~~~:J

DISC SIZE 20mm
V130PA20A • V320PA40C
102
103
104
105
106

~

50

VI

20
10.

INUt:tINIlt:

I_ _
~t-.

r"-

1....--""'" ,--.

l""

5

JI JII
10,000

FIGURE 5. SURGE CURRENT RATING CURVES FOR
V130PA20A· V320PA40C

2
IIIIII
'2LO-'--LLLLU1LOO~~~~-U~lu,O~0~0~L-~LLL1~O,~000
IMPULSE DURATION (~s)
FIGURE 6. SURGE CURRENT RATING CURVES FOR
V420PA40A· V660PA100C

NOTE: If pulse ratings are exceeded, a shift of VN(DC) (at specified current) of more than ±1 0% could result. This type of shift, which normally
results in a decrease of VN(DC)' may result in the device not meeting the original published specifications, but it does not prevent the
device from continuing to function, and to provide ample protection.

9·86

PA Series

Packaging

J
71~".n'o
-~~~ ~- T
~OJl

H,.2.~ ~

-Q

ffi~~ ·~

0P
2 HOLES

MILLIMETERS
SYMBOL

-T
00,

' IT
ba

TI

NOM

A

PLANE

0

MIN

aT

TAB

NOTES:

NOM

3.94

4.06

b3

3.05

3.17

MAX NOTES
0.570
0.260

6.6

b2

4.18

0.155

0.160 0.165

3.29

0.120

0.125 0.130
0.510

B

12.9

C

6.6

0.260

0

66.3

2.610

001

1. Tab is designed to fit 1/4" quick-connect terminal.

INCHES
MIN

14.3

b

_-..1

MAX

2. Case temperature is measured at T c on top surface of base
plate.

E

3. H, (130-150VRMS devices)
H2 (250-320V RMS devices)
Ha (420-660V RMS devices)

h

33.5

1.320

11.2

F

7.50

0.440

7.62

7.75

0.8

1.0

0.030 0.040

H,

25.6

1.010

3

4. Electrical conneclion: top terminal and base plate.

H2

28.3

1.120

3

5. Typical weight: 30g

H3

32.8

1.290

3

J

8.1

0.320

5.6

6.0

0.220

0.240

Q

50.6

50.8

51.0

1.990

2.000 2.010

S

18.4

19.2

20.0

0.72

0.75

1.0

0T

2.8

t:p

t

~ VARISTOR
LAYER i--=-+- - - - - - - +-----l__ MOUNTING
I::P

cp

I::P - - -

cp --

0.126

~

SURFACE
LOCK WASHER

LAYER

#10-32 NUT

Typical Non-Isolated Mounting

::':;'~~'i'::"",
WASHER

t : p - SPACER

(1)

THERMAL
GREASE

2

t~~'~~

"'\l'~-~.

CONNECT

t:p --- #10 FLAT WASHER

---r- - - -- - - 1 ' -

0.040

3.2

Suggested Hardware and Mounting
Arrangements

0.78

0.110

Tc

T~~~~~~ ~

0.300 0.305

0P

T

, ,-~~~"'''
~

0.295

I~
t:p
gJ

6--

___ VARISTOR

MICA INSULATOR

==== ==r:p _ -- ~8~~A~~G

LOCK WASHER

g J - 116-32 NUT

Typical Isolated Mounting

NOTES:
1. GE G623. Dow Corning. DC3. 4. 340. or 640 Thermal Grease
recommended for best heat transfer.
2. 1.000V isolation kit containing the following parts can be ordered
by part #A7811055.
1. MICA insulation 1"/3.1"/0.005" thick

2. Phenolic shoulder washer

1. '// quick-connect terminal

1. Spacer

2. #6 internal tooth lock washer
2. #6-32 nut

9-87

2. #6 flat washer

a:rJ)
011-(.)
rJ);:)
-0
a:O

~g:

RA Series
Low Profile Radial Lead Metal-Oxide
Varistors

August 1993

Features
• Recognized as "Transient Voltage Surge Suppressors", UL File
#E75961 to Std. 1449
• Recognized as "Transient Voltage Surge Suppressors", CSA File
#LR91788 to Std. C22.2No.1-M1981
• Low Profile Outline with Precise Seating Plane
• Continuous Temperature Operation •••••.•••..••••••.•.. +125 0 C
RASERIES

• Wide Operating Voltage Range VM(AC}RMS .•.••••••••••••••• 275V
• High Energy Absorption Capability WTM •••.••.•••.••• up to 140J
• 3 Mlldel Sizes Available .••••••..••..••.••. RA8, RA16, and RA22
• In-Line Leads for Ease In Automatic Placement

Description
RA series transient surge suppressors are low profile radial
lead varistors that feature a precise seating plane to
increase mechanical stability for secure circuit·board mounting. This feature makes these devices suitable for industrial
applications critical to vibration.

Absolute Maximum Ratings

The RA series are available in voltage ratings up to 275V
V M(AC}RMS, and energy levels up to 140J. Supplied in tape
and reel for use with automatic insertion equipment, these
varistors are also used in automotive, motor-control, tele·
communication, and military applications.

For ratings of individual members of a series, see Device Ratings and Characteristics chart
RA8SERIES

RA16 SERIES

RA22 SERIES

UNITS

4t0275
5.5 to 369

10 to 275
14 to 369

4 to 275
18 to 369

V
V

Transient:
Peak Pulse Current (ITM)
For 8/20l15ec Current Wave (See Figure 2) .................
Single Pulse Energy Range (Note 1)
For 1011 OOOl15ec Current Wave (WTM) .....................

100 to 1200

1000 to 4500

2000 to 6500

A

0.4 to 23

3.5 to 75

70 to 160

J

Operating Ambient Temperature Range (TA) ..................

-55 to +125

-55 to +125

-55 to +125

°C

Storage Temperature Range (TSTG ) .......... , ..............

-55 to +150

-55 to +150

-55 to +150

°C

Temperature Coefficient (aV) of Clamping Voltage (Vel at
Specified Test Current ...................................

Continuous:
Steady State Applied Voltage:
AC Voltage Range (VM(AC)RMS)' ..........................
DC Voltage Range (VM(oel ..............................

<0.01

<0.01

<0.01

"IoFC

Hi-Pot Encapsulation (Isolation Voltage Capability) .............
(Dielectric must withstand indicated DC voltage for one minute
per MIL-STD 202, Method 301)

5000

5000

5000

V

Insulation Resistance ....................................

1000

1000

1000

Mil

File Number

2193.2

Copyright © Harris Corporation t 993

9-88

Specifications RA Series
Device Ratings and Characteristics (Note 1)
RA8 Series
Series RA8 Varistors of 130VRMS or greater are listed under UL File No. E75961 as a recognized component. CSA approved File No. LR91788.
MAXIMUM RATINGS (+125°C)
CONTINUOUS

CHARACTERISTICS (+25°C)

TRANSIENT

MAX CLAMPING
VOLTAGE VcAT
TEST CURRENT
(8120j.1S)

TYPICAL
CAPAC!TANCE

RMS
VOLT·
AGE

DC
VOLT·
AGE

ENERGY
(101
10001lS)

DEVICE
MARK·
ING

VM(AC)

VM(DC)

WTM

11M

MIN

VN(DC)

MAX

Vc

Ip

(V)

(V)

(J)

(A)

(V)

(V)

(V)

(V)

(A)

(pF)

V8RA8

8R

4

5.5

0.4

150

6

8.2

11.2

22

5

3000

V12RA8

12R

6

8

0.6

150

9

12

16

34

5

2500

V18RA8

18R

10

14

0.8

250

14.4

18

21.6

42

5

2000

V22RA8

22R

14

18
(Note 3)

10
(Note 2)

250

18.7

22

26

47

5

1600

MODEL
NUMBER

PEAK
CURRENT
(8I2OIlS)

VARISTOR VOLTAGE AT
lmA DC TEST
CURRENT

1= 1MHz

V27RA8

27R

17

22

1.0

250

23

27

31.1

57

5

1300

V33RA8

33R

20

26

1.2

250

29.5

33

36.5

68

5

1100

V39RA8

39R

25

31

1.5

250

35

39

43

79

5

900

V47RA8

47R

30

38

1.8

250

42

47

52

92

5

800

V56RA8

56R

35

45

2.3

250

50

56

62

107

5

700

V68RA8

68R

40

56

3.0

250

61

68

75

127

5

600

V82RA8

82R

50

66

4.0

1200

74

82

91

135

10

500

V100RA8

100R

60

81

5.0

1200

90

100

110

165

10

400

V120RA8

120R

75

102

6.0

1200

108

120

132

205

10

300

V150RA8

150R

95

127

8.0

1200

135

150

165

250

10

250

V80RA8

180R

115

153

10.0

1200

162

180

198

295

10

200

V200RA8

200R

130

175

11.0

1200

184

200

228

340

10

180

V220RA8

220R

140

180

12.0

1200

198

220

242

360

10

160

V240RA8

240R

150

200

13.0

1200

212

240

268

395

10

150

V270RA8

270R

175

225

15.0

1200

247

270

303

455

10

130

V360RA8

360R

230

300

20.0

1200

324

360

396

595

10

100

V390RA8

390R

250

330

21.0

1200

354

390

429

650

10

90

V430RA8

430R

275

369

23.0

1200

389

430

473

710

10

80

NOTES:
1. Average power dissipation of transients not to exceed 0.25W for RA8 Series.
2. Energy ratings for impulse duration of 30ms minimum to one half of peak current value.
3. Also rated to withstand 24V for 5 minutes.

9·89

a:(f)

011-0
(f)::::l
-0
a:O

~g:

Specifications RA Series
Device Ratings and Characteristics (Note 1) (Continued)
RA16 Series
Series RA16 and RA22 Varistors of 130VRMS or greater are listed under UL File No. E75961 as a recognized component.
CSA approved File No. LR91788.
CHARACTERISTICS (+25 OC)

MAXIMUM RATINGS (+125°C)
CONTINUOUS

TRANSIENT
VARISTOR VOLTAGE AT
1mA DC TEST
CURRENT

MAX CLAMPING
VOLTAGE VcAT
TEST CURRENT
(8/20115)

TYPICAL
CAPACITANCE

RMS
VOLTAGE

DC
VOLTAGE

ENERGY
(10/
1000115)

DEVICE
MARKING

VM(AC)

VM(OC)

WTM

ITM

MIN

VN(OC)

MAX

Vc

Ip

(V)

(V)

(J)

(A)

(V)

(V)

(V)

(V)

(A)

(pF)

V18RA16

18R16

10

14

3.5

1000

14.4

18

21.6

39

10

11000

V22RA16

22R16

14

18
(Note 3)

50
(Note 2)

1000

18.7

22

26

43

10

9000

V27RA16

27R16

17

22

5.0

1000

23

27

31.1

53

10

7000

V33RA16

33R16

20

26

6.0

1000

29.5

33

36.5

64

10

6000

V39RA16

39R16

25

31

7.2

1000

35

39

43

76

10

5000

V47RA16

47R16

30

38

8.8

1000

42

47

52

89

10

4500

V56RA16

56R16

35

45

10.0

1000

50

56

62

103

10

3900

V68RA16

68R16

40

56

13.0

1000

61

68

75

123

10

3300

V82RA16

82R16

50

66

15.0

4500

74

82

90

145

50

2500

V100RA16

100R16

60

81

20.0

4500

90

100

110

175

50

2000

V120RA16

120R16

75

102

22.0

4500

108

120

132

205

50

1700

V150RA16

150R16

95

127

30.0

4500

135

150

165

255

50

1400

V180RA16

180R16

115

153

35.0

4500

162

180

198

300

50

1100

V200RA16

200R16

130

175

38.0

4500

184

200

228

340

50

1000

V220RA16

220R16

140

180

42.0

4500

198

220

242

360

50

900

V240RA16

240R16

150

200

45.0

4500

212

240

268

395

50

800

V270RA16

270R16

175

225

55.0

4500

247

270

303

455

50

700
550

MODEL
NUMBER

PEAK
CURRENT
(8120115)

1= 1MHz

V360RA16

360R16

230

300

70.0

4500

324

360

396

595

50

V390RA16

390R16

250

330

72.0

4500

354

390

429

650

50

500

V430RA16

430R16

275

369

75.0

4500

389

430

473

710

50

450

RA22 Series
V24RA22

24R22

14

18
(Note 3)

100.0
(Note 2)

2000

19.2

24
(Note 4)

26

43

20

18000

V36RA22

36R22

23

31

160.0
(Note 2)

2000

32

36
(Note 4)

40

63

20

12000

V200RA22

200R22

130

175

70.0

6500

184

200

2288

340

100

1900

V240RA22

240R22

150

200

80.0

6500

212

240

268

395

100

1600

V270RA22

270R22

175

225

90.0

6500

247

270

303

455

100

1400

V390RA22

390R22

250

330

130.0

6500

354

390

429

650

100

1000

V430RA22

430R22

275

369

140.0

6500

389

430

473

710

100

900

NOTES:
1. Average power dissipation of transients not to exceed 0.60W for RA 16 Series. or 1.0W for RA22 Series.
2. Energy ratings for impulse duration of 30ms minimum to one half of peak current value.
3. Also rated to withstand 24V for 5 minutes.
4. 10mA DC Test Current.

9-90

RA Series

..

,,,-

Power Dissipation Requirements
Transients in a suppressor generate heat too quickly for it to
be transferred to the surroundings during the pulse interval.
Continuous power dissipation capability, therefore, is not a
necessary design requirement for a suppressor, unless transients occur in rapid succession. Under this condition, the
average power dissipation required is simply the energy
(watt-seconds) per pulse times the number of pulses per
second. The power so developed must be within the specifications shown on the Device Ratings and Characteristics
table for the specific device. Furthermore, the operating values need to be derated at high temperatures as shown in
Figure 1. Because varistors can only dissipate a relatively
small amount of average power they are, therefore, not suitable for repetitive applications that involve substantial
amounts of average power dissipation.

100

~

w
=> 90
oJ
~ so
ew 70
~
a: 60
IL
0 50
z 40

~

\

...

\

w

I\.
~

~ 30

~ 20
10
0
-55

L\
50

60

70 so 90 100 110 120 130 140 150
AMBIENT TEMPERATURE (OC)

FIGURE 1. CURRENT, ENERGY AND POWER DERATING
CURVE
w
3100
~
90
~
w

...
...z~

/

w

~
~

10

/

..

50

0,-

f

\

ii'i

r

0, =Virtual Origin of Wave
T = Time From 10% to 90% of Peak
T, = Virtual Front time =1.25 • t
T2 =Virtual Time to Half Value (Impulse Duration)
Example: For an 8120115 Current Waveform:
aIlS =T, =Virtual Front Time
201lS =T2 =Virtual Time to Half Value

~
TIME

T
I - - -T , T2

FIGURE 2. PEAK PULSE CURRENT TEST WAVEFORM

Transient V-I Characteristics Curves
500
400 I- MAXIMUM CLAMPING VOLTAGE
STO 6SVN(DC) RATING
300 I- TA =-55°C TO +12SoC

t-

~

~200
VI

!:i

g 100
90
so
"«w 70
Q.

60

::; 50
=>
::; 40

~

:;;

30
20
10

10.3

IV6SRAS
V56RAS
V47RAS
V39RAS
V33RAS
V27RAS
V22RAS
V1SRA8
V12RAS
11111111
VSRAS
10.2

~
~

l-

~

gl,ggg

1/

V

f-f-10"
10'
10°
PEAK AMPERES (A)

102

4,000
MAXIMUM CLAMPING VOLTAGE
3,000 t- MODEL SIZE 5 x Smm
82 TO 430VNg>C) RATING
TA =-5SoC T +125°C
2,000
IHI
~
V240RAS
VI
t111111111111111
V220RAS
!:i
V200RA..!!::;::
V430RAS
V390RAS
"« 700
800
~ 600
::; 500
=> 400 V360RA8
i!!
V270RAS
I-'
~ 300 I I 1111111
j;'
200 V1S0RAS
V150RA8
V
V120RA8
V82RA8
Vl00RAB
~B
100
10.2
10-3
10"
10°
10'
102
103 104
PEAK AMPERES (A)
FIGURE 4. CLAMPING VOLTAGE FOR V82RA8 - V430RA8

103

FIGURE 3. CLAMPING VOLTAGE FOR V8RA8 - V68RA8

9-91

--

r-

RA Series
Transient V-I Characteristics Curves (Continued)
600
SOD
400
300

-

'" 200

-

~
~

~
:.:

~ 1~~

:;

i

~

:;

70
60
50
40
30

4,000

MAXIMUM CLAMPING VOLTAGE
lB TO 6BVNfDC) RATING
TA = -Ssoc 0 +12SoC

2,000

'"

~

-

~

----

=

V6BRA16
VS6RA16
V47RA16
V39RA16
V33RA16
V27RA16V22RA16
V1BRA16-

~

t:::

f-'"

V

:.: BOO
« 700
~ 600
:; SOD
:;:) 400 V360RAl
:!!
V270RA16
~ 300

:;

200

V240RA16
V220RAB
V200RAB

1111111111111111

~
~1,g88

V430RA16
V390RA16

1-

V~B~J~;I~

V150RA16
V120RA16
Vl00RA16
100
10.3
10.2

FIGURE 5. CLAMPING VOLTAGE FOR V18RA16 - V68RA16

l-

i.-

~

"YB2RA16
10.1

100
101
102
PEAK AMPERES (A)

103

104

FIGURE 6. CLAMPING VOLTAGE FOR V82RA16· V430RA16
4,000

300

MAXIMUM CLAMPING VOLTAGE
24 TO 36VNfDC) RATING
TA -Ssoc 0 +12SoC

3,000

=

200

~

V

~

100
:.: 90
BO
... 70
:; 60

>

900

W

600
SOD
400

~

40

...

V36RA22

-

50

~

V

::;

f--

V24RA22

1IIIIIvLl~~21

V390RA221~

¥88

'"

10.1

V270RA22
V240RA22
V200RA22

200

1111111111
10.2

=

~ 300

30
20
10.3

MAXIMUM CLAMPING VOLTAGE
200 TO 430VN(DC) RATING
TA .Ssoc TO +125 0 C

'"91,000

I1i
:;:)

r-

2,000

'"~

~
:;

1111

~

10.1
100
101
PEAK AMPERES (A)

:;

MAXIMUM CLAMPING VOLTAGE
MODEL SIZE S x Bmm
B2 TO 430VNg>C) RATING
TA = -Ssoc T +12SoC

3,000

100
101
102
PEAK AMPERES (A)

103

10~0·3

104

11111111 11111111
10.2

10.1

100
101
102
PEAK AMPERES (A)

103

104

FIGURE S. CLAMPING VOLTAGE FOR V200RA22· V430RA22

FIGURE 7. CLAMPIING VOLTAGE FOR V24RA22 - V36RA22

Pulse Rating Curves
200
100
50

g

2;::: 1=

-.JO

20

II:
II:

10

..J..03

UI

I I II
104
105
106

500

-

vaRAB - V12RAB

100

g

"'i- Ch

l-

)'7 ;,('

Z

UI

:;:)

20

u

10

CJ

S

U

II:

:;:)

'"

2

-

=~
0.5

r-...

7-.."

--~~

INDEFINITE

100

w

r--;

..........

::::::

1,000
IMPULSE DURATION (~.)

II:

I"'~ I"'-r-

:;:)

'"

~r-

2-

_

104

/O~06

10<.,10 2
SO

II:
II:
:;:)

UI
Cl

V1BRA8 - V68RA8

k:'1
200

........

-..l,!!2

z

I-

........... 1

~03

1'--_

-

2 I-

r...

.z:t. ....

I'

(

r-c.
INDEFINITE

--

r-....

1--_

I"-

~
,....,

r-.:-

~~

O.S

0.220

10,000

FIGURE 9. SURGE CURRENT RATING CURVES FOR V8RA8V12RA8

100

1,000
IMPULSE DURATION (~s)

10,000

FIGURE 10. SURGE CURRENT RATING CURVES FORV18RA8V66RA6

9-92

RA Series

Pulse Rating Curves (Continued)
1,000
500

g 200
I-

100

~
a:

50

~

20

~

10

z

::>
(!J

en

5

~1

..to

1,000
IMPULSE DURATION (~s)

Q R'y.

-=,

::::t:::

-t-

IZ

w
a:
a:

1,000

V82RA16 - V430RA16

200

::>

100

w
a:

50

en

20

0

(!J

::>

1,000

~ri'

10 2
10 3

~...

~

r-....

500

g

~/104105 6

500

IZ

10

a: 100
a:

::>
0

10
5
2
20

-.......

=
INDEFINITE

200

w

........ -:-; ~~

i"-

::>

::::::;::: ~::--

en

2,000
_ 1,000
~ 500

I"

10,000

V24RA22 - V36RA22

--

10

N 02
10 3

~

r--.......

20

"""1-

r--

TE

100

106

~

....

r-- r-2:
~EFlNI

2
20

10,000

FIGURE 13. SURGE CURREENT RATING CURVES FOR
V82RA16 - V430RA16
10,000
5,000

r---.
........

1,000
IMPULSE DURATION (~.)

R:t-- 1

50 ~5

10

100
1,000
IMPULSE DURATION (~s)

::::-

........

w

a:

:--.... ......

I"'-r-.

[:::::r---

II IIII

(!J

....

...........

i-

FIGURE 12. SURGE CURRENT RATING CURVES FOR V18RA 16
- V68RA16

2,000 ",,2

g

V18RA16 - V68R A16

INDEFINITE

100

2,000

kl

~

10,000

FIGURE 11. SURGE CURRENT RATING CURVES FOR V82RA8V430RA8

5,000

.......

102'

-':"::"'r-.

2
100

103
104
105
10 6

r7

---

.....

~

1,000
IMPULSE DURATION (~.)

i"-

10,000

FIGURE 14. SURGE CURRENT RATING CURVES FORV24RA22
- V36RA22

a:cn

1

2
10=

...... r-....

I-

V200RA22 - V430RA22

=

10·
,/10 3 4
10 5
10106

"

w

::>

200
100

w

50

a:

20

0

r--

(!J

::>

en

10

INDEFINIT E

.....,

~

r--

-

~

~ ~ I::::t'

2
100

1,000
IMPULSE DURATION (~s)

10,000

FIGURE 15. SURGE CURRENT CURVES FOR V200RA22 - V430RA22

NOTE: If pulse ratings are exceeded, a shift of VN(DC) (at specified current) of more than ±1 0% could result. This type of shift, which normally
results in a decrease of VN(OC), may result in the device not meeting the original published specifications, but it does not prevent the
device from continuing to function, and to provide ample protection.

9-93

cn:::l
-0
a:O

~g:

Z

a:
a:

011-0

RA Series
Packaging

vI"-

L
r

t

I

n
MIN

I

AM AX
SEATING,

RA16
SERIES

RA22
SERIES

A MAX

8.85
(0.348)

15.1
(0.594)

19.1
(0.752)

DMAX

11.45
(0.450)

19.7
(0.776)

25.5
(1.004)

e

5
(0.197)

7.5
(0.295)

7.5
(0.295)

EMAX

5.2
(0.205)

6.3
(0.248)

6.3
(0.248)

nMAX

0.7
(0.027)

0.7
(0.027)

0.7
(0.027)

0b

0.635
(0.025)

0.81
(0.032)

0.81
(0.032)

WEIGHT

1 Gram

3.4 Grams

4.4 Grams

X

2.2
(0.087)

2.2
(0.087)

4.4
(0.173)

Y

3.1 ± 0.5
(0.122 ±
0.02)

6±1
(0.236 ± 0.04)

8.9 ± 1
(0.35 ± 0.04)

PLANE

IJ

I

X

0b

±o.os

RA8
SERIES

SYMBOL

_I 1_
± 0.002)--' .

5.0 MIN
(0.197 MIN)

i

r-

+-+
L~
t
, ~t

M~

± 1.0
(± 0.039)

t -t-r; ~'"
0.5 MAX

(0.020 MAX

TYP

NOTES:
1. Dimensions in mm, dimensions in inches in parentheses.
2. Inches for reference only.

9-94

ZA Series

HARRIS
SEMICONDUCTOR

Radial Lead Metal-Oxide Varistors for
Low-to-Medium Voltage Operation

August 1993

Features
• Recognized as "Transient Voltage Surge Suppressors", UL File
#E135010 to Std. 497B
• Wide Operating Voltage Range VM(AC)RMS .•......•...• 4V to 460V
• DC Voltage Ratings •••••••••••••••••..••.•..•.•.. 5.5V to 615V
• 5 Model Sizes Available ••.••..•.••••.••.• 5,7,10,14, and 20mm
• Radial-Lead Package for Compact Hard-Wired Printed Circuit Board
Designs
5.7,10, 14,20mm
ZA SERIES

• Available in Tape and Reel for Use With Automatic Insertion Equipment

Description
ZA series transient surge suppressors are radial-lead varistors designed for use in the protection of low and mediumvoltage circuits (5V or less) of electronic systems. These
systems, whose components because of smaller geometries, faster switching times, and less power consumption,
are becoming more sensitive to failure and malfunction due
to voltage transients. Because of their radial-lead construc-

Absolute Maximum Ratings

tion, ZA series devices require very little mounting space, a
feature of importance in compact, hard-wired printed circuit
board systems.
These devices are available in five model sizes: 5mm, 7mm,
10mm, 14mm and 20mm, and feature a wide VM(AC)RMS voltage of 4V to 460V.

For ratings of individual members of a series, see Device Ratings and Characteristics chart
ZA SERIES

UNITS

4 to 460
5.5 to 615

V
V

Transient:
Peak Pulse Current (ITM)
For 8/20llS Current Wave (See Figure 2) ..........•...............•.................
Single Pulse Energy Range (Note 1)
For 10/1330001lS Current Wave (W TM ) ............................................. .

25 to 4500

A

0.1 to 35

J

Operating AmbientTemperature Range (TA)' ......................................... .

·55 to +85

Continuous:
Steady State Applied Voltage:
AC Voltage Range (VM(AC)RMS)' ........•......•............•..•...•......•.....•..
DC Voltage Range (VM(DC) ....................•..•..•...........................

II:

~g:

Storage Temperature Range (TSTG)' ................................................ .

-55 to +125

°c
°c

Temperature Coefficient (eN) of Clamping Voltage (Vel at Specified Test Current. ............ .

<0.01

%f'C

Hi-Pot Encapsulation (Isolation Voltage Capability) ...................................•..

2500

V

1000

Mil

(Dielectric must withstand indicated DC voltage for one minute per MIL-STD 202, Method 301) .
Insulation Resistance ........•................•................................•..
NOTE:
1. Ratings on specific types can be as high as 160J for an impulse duration of 30ms minimum to 1/2 of peak current value.

CAUTION: These devices are

sens~ive

Copyright © Harris Corporation 1993

to electrostatic discharge. Users should follow proper I.C. Handling Procedures.

9-95

File Number

en

011-0
en::;)
-0
11:0

2184.2

ZA Series
Device Ratings and Characteristics (Note 1)
ZA Series Varistors are listed under UL File No. E135010 as a UL recognized component.
CHARACTERISTICS (+25°C)

MAXIMUM RATINGS (+85°C)
CONTINUOUS
MODEL
SIZE
DISC
DEVICE
DIA.
MODEL
MARK·
NUMBER
(mm)
ING

RMS
VOLT·
AGE

DC
VOLTAGE

TRANSIENT
ENERGY
PEAK
CURRENT
(101
1000~s)

(8/20~s)

VARISTOR VOLTAGE
AT lmA DC TEST
CURRENT

MAX CLAMP·
INGVOLTAGE
VcATTEST
CURRENT
(8/20~s)

TYPICAL
CAPACI·
TANCE

VM(AC)

VM(OC)

WTM

ITM

MIN

VN(DC)

MAX

Vc

Ip

(V)

(V)

(J)

(A)

(V)

(V)

(V)

(V)

(Al

1= lMHz
(pF)

V8ZA05
V8ZAl
V8ZA2

5
7
10

Z08
08Z1
08Z2

4
4
4

5.5
5.5
5.5

0.1
0.4
0.8

50
100
250

6.0
6.0
6.0

8.2
8.2
8.2

11.0
11.0
11.0

30
22
20

2
5
5

1400
3000
7500

V12ZA05
V12ZAl
V12ZA2

5
7
10

Z12
12Z1
12Z2

6

6
6

8
8
8

0.14
0.6
1.2

100
250
2S0

9.0
9.0
9.0

12
12
12

16.0
16.0
16.0

37
34
30

2
5
5

1200
2S00
6000

V18ZA05
V18ZAl
V18ZA2
V18ZA3
V18ZA40

5
7
10
14
20

Z18
18Z1
18Z2
18Z3
18Z40

10
10
10
10
10

14
14
14
14
14

0.17
0.8
1.S
3.S
80.0
(Note 2)

100
2S0
500
1000
2000

14.4
14.4
14.4
14.4
14.4

18
18
18
18
18
(Note 3)

21.6
21.6
21.6
21.6
21.6

44
42
39
39
37

2
5
10
20

1000
2000
SOOO
11000
22000

V22ZA05
V22ZAl
V22ZA2
V22ZA3

7
10
14

Z22
22Z1
22Z2
22Z3

14
14
14
14

18 (Note 4)
18 (Note 4)
18 (Note 4)
18 (Note 4)

0.2
0.9
2.0
4.0

100
2S0
500
1000

18.7
18.7
18.7
18.7

22
22
22
22

26.0
26.0
26.0
26.0

51
47
43
43

2
5
5
10

800
1600
4000
9000

V24ZA50

20

24Z50

14

18 (Note 4)

100.0
(Note 2)

2000

19.2

24
(Note 3)

26.0

43

20

18000

V27ZAOS
V27ZAl
V27ZA2
V27ZM
V27ZA60

5
7
10
14
20

Z27
27Z1
27Z2
27Z4
27Z60

17
17
17
17
17

22
22
22
22
22

0.25
1.0
2.5
5.0
120.0
(Note 2)

100
250
500
1000
2000

23.0
23.0
23.0
23.0
23.0

27
27
27
27
27
(Note 3)

31.1
31.1
31.1
31.1
31.1

59
57
53
53
50

2
5
5
10
20

600
1300
3000
7000
15000

V33ZAOS
V33ZAl
V33ZA2
V33ZAS
V33ZA70

5
7
10
14
20

Z33
33Z1
33Z2
33Z5
33Z70

20
20
20
20
21

26
26
26
26
27

0.3
1.2
3.0
6.0
150.0
(Note 2)

100
2S0
500
1000
2000

29.5
29.5
29.5
29.5
29.5

33
33
33
33
33
(Note 3)

38.0
36.S
36.5
36.5
36.5

67
68
64
64
58

2
5
5
20

500
1100
2700
6000
13000

V26ZA80

20

36Z80

23

31

160.0
(Note 2)

2000

32.0

36
(Note 3)

40.0

63

20

12000

V39ZA05
V39ZAI
V39ZA3
V39ZA6

5
7
10
14

Z39
39Z1
39Z3
39Z6

25
25
25
25

31
31
31
31

0.35
1.5
3.5
7.2

100
250
500
1000

35.0
3S.0
3S.0
3S.0

39
39
39
39

46.0
43.0
43.0
43.0

79
79
76
76

2
5
S
10

440
900
2200
5000

5

5

10

NOTES:
1. Average power dissipation 01 transients not to exceed 0.2W, 0.25W, O.4W, 0.6W or 1W lor model sizes 5mm, 7mm, 10mm, 14mm and
20mm, respectively.
2. Energy rating lor impulse duration of 30ms minimum to one half of peak current.
3. 1OmA DC test current.
4. Also rated to withstand 24V for 5 minutes.

9·96

ZA Series
Device Ratings and Characteristics

(Notes 1,2)

ZA Series Varistors are listed under UL File No. E135010

as a UL recognized component.
CHARACTERISTICS (+25°C)

MAXIMUM RATINGS (+85°C)
CONTINUOUS

MODEL
NUMBER

MODEL
SIZE
DISC
DEVICE
DIA.
MARK·
(mm)
ING

TRANSIENT
ENERGY
PEAK
(101
CURRENT
(8/20I1 s)
100011s)

VARISTOR VOLTAGE
AT 1mA DC TEST
CURRENT

MAX CLAMP·
ING VOLTAGE
Vc AT TEST
CURRENT
(8/20I1s)

TYPICAL
CAPACI·
TANCE

RMS
VOLT·
AGE

DC
VOLTAGE

VM(AC)

VM(DC)

WTM

ITM

MIN

VN(DC)

MAX

Vc

Ip

1= 1MHz

(V)

(V)

(J)

(A)

(V)

(V)

(V)

(V)

(A)

(pF)

V47ZA05
V47ZAI
V47ZA3
V47ZA7

5
7
10
14

Z47
47Z1
47Z3
47Z7

30
30
30
30

38
38
38
38

0.4
1.8
4.5
8.8

100
250
500
1000

42
42
42
42

47
47
47
47

55
52
52
52

90
92
89
89

2
5
5
10

400
800
2000
4500

V56ZA05
V56ZA2
V56ZA3
V56ZA8

5
7
10
14

Z56
56Z2
56Z3
56Z8

35
35
35
35

45
45
45
45

0.5
2.3
5.5
10.0

00
250
500
1000

50
50
50
50

56
56
56
56

66
62
62
62

108
107
103
103

2
5
5
10

360
700
1800
3900

V68ZA05
V68ZA2
V68ZA3
V68ZA10

5
7
10
14

Z68
68Z2
68Z3
68Z10

40
40
40
40

56
56
56
56

0.6
3.0
6.5
13.0

100
250
500
1000

61
61
61
61

68
68
68
68

80
75
75
75

127
127
123
123

2
5
5
10

300
600
1500
3300

V82ZA05
V82ZA2
V82ZM
V82ZA12

5
7
10
14

Z82
82Z2
82Z4
82Z12

50
50
50
50

66
66
66
66

2.0
4.0
8.0
15.0

400
1200
2500
4500

73
73
73
73

82
82
82
82

97
91
91
91

135
135
135
145

5
10
25
50

240
500
1100
2500

Vl00ZA05
Vl00ZA3
Vl00ZM
Vl00ZA15

5
7
10
14

Z100
100Z
100Z4
100Z15

60
60
60
60

81
81
81
81

2.5
5.0
10.0
20.0

400
1200
2500
4500

90
90
90
90

100
100
100
100

117
110
110
110

165
165
165
175

5
10
25
50

180
400
900
2000

V120ZA05
V120ZAI
V120ZM
V120ZA6

5
7
10
14

Z120
120Z
120Z4
120Z6

75
75
75
75

102
102
102
102

3.0
6.0
12.0
22.0

400
1200
2500
4500

108
108
108
108

120
120
120
120

138
132
132
132

205
205
200
210

5
10
25
50

140
300
750
1700

V150ZA05
V150ZAI
V150ZA5
V150ZA10

5
7
10
14

Z150
Z051
150Z4
150Z10

92
95
95
95

127
127
127
127

4.0
8.0
15.0
30.0

400
1200
2500
4500

135
135
135
135

150
150
150
150

173
165
165
165

250
250
250
255

5
10
25
50

120
250
600
1400

V180ZA05
V180ZAI
V180ZA5
V180ZA10

5
7
10
14

Z180
180Z
180Z5
180Z10

110
115
115
115

153
153
153
153

5.0
10.0
18.0
35.0

400
1200
2500
4500

162
162
162
162

180
180
180
180

207
198
198
198

295
295
300
300

5
10
25
50

100
200
500
1100

V220ZA05

5

Z220

140

180

6.0

400

198

220

253

360

5

90

V270ZA05

5

Z270

175

225

7.5

400

243

270

311

440

5

70

V330ZA05

5

Z330

210

275

9.0

400

297

330

380

540

5

60

V390ZA05

5

Z390

250

330

10.0

400

351

390

449

640

5

50

V430ZA05

5

Z430

275

369

11.0

400

387

430

495

700

5

45

V470ZA05

5

Z470

300

385

12.0

400

420

470

517

775

5

35

V680ZA05

5

Z680

420

560

14.0

400

610

680

748

1120

5

32

460

615

17.0

400

675

750

825

1240

5

30

.

910

.

5

28

V750ZA05

5

Z750

V910ZA05

5

Z910

.

NOTES:
1. Average power dissipation of transients not to exceed 0.2W, 0.25W, O.4W, 0.6W or lW for model sizes 5mm, 7mm, 10mm, 14mm and
20mm, respectively.

2. Higher voltages a vailable, contact Harris Semiconductor Power Marketing

9-97

0:C/I

01-

U
IC/I::)

-0
0:0

~g:

ZA Series
Power Dissipation RequIrements

100

Transients in a suppressor generate heat too quickly for it to
be transferred to the surroundings during the pulse interval.
Continuous power dissipation capability, therefore, is not a
necessary design requirement for a suppressor, unless tran·
sients occur in rapid succession. Under this condition, the
average power dissipation required is simply the energy
(watt·seconds) per pulse times the number of pulses per
second. The power so developed must be within the specifi·
cations shown on the Device Ratings and Characteristics
table for the specific device. Furthermore, the operating val·
ues need to be derated at high temperatures as shown in
Figure 1. Because varistors can only dissipate a relatively
small amount of average power they are, therefore, not suit·
able for repetitive applications that involve substantial
amounts of average power dissipation.

110

\

w 80

:::I

~

....I

~ 70
Q
60
~
a: 50

~

II.

0

I-

zw

,

~

~

40

~

u 30
a:

\

w 20

Q.

10
0
·ss

so

60

I~
70 80 90 100 110 120 130 140 lS0
AMBIENT TEMPERATURE ("Cl

FIGURE 1. CURRENT, ENERGY AND POWER DERATING
CURVE

w

:l100
~
90
~

'"
w

a..

II.

0

l-

SO

z
w
u
a:

I

.1

/

..'

w

Q.

10

\

°T ==Time
Virtual Origin of Wave
From 10% to 90% of Peak
1

TI =Virtual Front time =1.25 • t
T2 =Virtual Time to Half Value (Impulse Duration)
Example: For an 8120115 Current Waveform:
81lS =T1 =Virtual Front Time
201lS =T2 =Virtual Time to Half Value

~

o,_ iiil-- T-

TIME

I~TlT2

FIGURE 2. PEAK PULSE CURRENT TEST WAVEFORM

Transient V-I Characteristics Curves
600

SOD
400
300
E 200

E2,ooo

l0-

CI)

!.:i
0

>

~

100

::I!

is

~
a..
:::I

::I!

~

::I!

5,000
4,000 f3,000 f-

~~~~~~I~~~OLTAGE _
8 TO 68VN(DC) RATING
TA • -5SoC TO i-8SoC
-

I--'r-

CI)

~~
~~

V56ZA
V47ZAg~fV39ZA
V33ZA 05
V27ZA05
V22ZA05
V18ZA05
Vl2ZA05
20

osf-

VeZA~~'I--'I-10 I 1111111
10.2
10-3

11

~

soo
400
300
::I!
200

~

I--'
!-'"

I III

10.1
10°
101
102
103
PEAK AMPERES CAl
FIGURE 3. CLAMPING VOLTAGE FOR V8ZA05- V68ZA05

9-98

~~

l-

V910ZA05

~ 1'3g8 ~m~g~
~ 988
Q.
600

!,...o

I--

JJJJlI~r

V430ZAOSV470ZAOS

!:i
0

90 rv68ZA05

SO
40
30

MAX CLAMPING VOLTAGE
MODEL SIZE Smm
82 TO 91 OVNg>C) RATING
TA =.SSoc T i-8SoC
111111111 11111"11 11111

V390ZAOS
V330ZA05
V270ZA05
V220ZA05
V180ZA05
V150ZA05
V120ZA05
Vl00ZA05[_
100 Ve2ZA05
10.3
10.2

F""
~

rL

~

~

H-

10.1
102 103
101
10°
PEAK AMPERES CAl
FIGURE 4. CLAMPING VOLTAGE FOR V82ZA05- V910ZA05

ZA Series
Transient V-I Characteristics Curves (Continued)
4,000

500
400

r-

300

r--

MAXIMUM CLAMPING VOLTAGE
8 TO 68VN(DC) RATING
TA = -Ssoc TO +8SoC

i-'

!i! 100
><: 90
..: 80
w 70
Q.
60
~ 50
::;; 40

~

::;;

2,000

/,

~200

'"
!:i
V68ZA2
VS6ZA2
V47ZAl
V39ZAl
V33ZAl
V27ZAl
V22ZA
V18ZA
V12ZAl

30

~f-

20

11111111
V8ZAl
10
10-3

10.2

I---'
I---'

~

%
~

'"
!:i

~

~

r-300 r--

102

JIIIIII

!i! 100
><: 90
..: 80
w 70
Q.
60
~ 50
::;; 40

~

::;;

V68ZA3
VS6ZA3
V47ZA3
V39ZA3
V33ZA2
V27ZA2 V22ZA2
_i-'
V18ZA2

30
20

V12ZA2 -

IV~~~I..\00.3

10-2

f-'

10-1

4,000
3,000

~~

'"
!:i

;'-1-"

1I111111111111111

!i! l,g8g
800
..: 700
w 600
~ 500
400

./

....
,...i-'

f-'
f-'

,/

300

~

300

102

10~0·3

103

::;;

i

~

::;;

70
60
SO
40
30

.....

V68ZA10
VS6ZA8
V47ZA7
V39ZA6
V33ZAS
V27Z A4 ,...
V22ZA3
V18Z A3 f-'

2~0·3

10-2

II-

10-2

10-1

100
101
102
PEAK AMPERES (A)

V
V
103

104

3,000
2,000

MAXIMUM CLAMPING VOLTAGE
MODEL SIZE 14mm
82 TO 180VNg>C) RATING
TA = _55°C T +8S oC

~

!i!

~ li~

i-'

FIGURE S. CLAMPING VOLTAGE FOR V82ZA4 - V1S0ZA5
4,000

!:i
><:

r/

J

200

I

'" 200

V~~o:1:4A4 "-

::;;

f-'

10.1
100
101
PEAK AMPERES (A)

V180ZAS
V1S0ZA4
V120ZA4

i

I---'

MAXIMUM CLAMPING VOLTAGE
MODEL SIZE 14mm
18 TO 68VNfDC) RATING
TA = -SSoc 0 +8S oC

~

MAXIMUM CLAMPING VOLTAGE
MODEL SIZE 7mm
82 TO 180VNg>C~ RATING
TA = -55°C T + SoC

><:

f-'

100
101
102
PEAK AMPERES (A)

~

FIGURE 7. CLAMPING VOLTAGE FOR VSZA2 - V68ZA3
600
500
400

r--

2,000

f-'
f-'

-

1-'"
l-

...
...

FIGURE 6. PULSE RATING CURVES FOR VS2ZA2 - V1S0ZA1

1111

'"
!:i

~

IS

103

MAXIMUM CLAMPING VOLTAGE
MODEL SIZE 10mm
8 TO 68VN(Dg> RATING
TA = -SSoc T +8SoC

~200

I~

300
200

FIGURE 5. PULSE RATING CURVES FOR V8ZA1 - V68ZA2
500
400

Vl00ZA3
V82ZA2

::;;

I--'

10-1
100
101
PEAK AMPERES (A)

V180ZAl
V1S0ZAl -

V120ZA1~

i

/

-

111111111111111111

!i!l,ggg
><: 800
..: 700
~ 600
::;; 500
400

.....

--

MAXIMUM CLAMPING VOLTAGE
MODEL SIZE 7mm
82 TO 180VNg>C) RATING
TA = -SSoc T +8SoC

3,000

---

(::
,..,.

10-1
100
101
PEAK AMPERES (A)

'"
!:i

~

11111111111111111
,'"
,,"

..

!i!l.ggg

~ ~gg

k'

~

i

Vl00ZA15
V82ZA12

~ 300

,/

..

V180ZA10

v~~~~!~8 "
~""

600
::;; 500
400

::;;

I"~

-

200

1/

~

I102

103

100
10-3

10-2

10.1

100
10 1
102
PEAK AMPERES (A)

103

104

FIGURE 10_ CLAMPING VOLTAGE FOR VS2ZA 12 - V180ZA 10

FIGURE 9. CLAMPING VOLTAGE FOR V18ZA3 - V68ZA10

9-99

ZA Series
Transient V-I Characteristics Curves (Continued)
300

MAXIMUM CLAMPING VOLTAGE
MODEL SIZE 20mm
I18
TO 36VNfDC) RATING
200
TA ,,-55°C 0 +ssoC

~

V36ZASO

g 100 I"
~

11.

:;;
::>
:;;

~

::;;

~

111111111 111111111

Ul

!:i

v~ii~~O

90 I-80 I-70 I-60 l-

"-

V24ZASO
V1SZA40 ~

r/J

~

~

f-"'

50

f-

i--'

l-

30

V

~

I-

40

f20
10.3

10.2

10.1

100
101
102
PEAK AMPERES (A)

103

104

FIGURE 11. CLAMPING VOLTAGE FOR V18ZMO - V36ZA80

Pulse Rating Curves
50
20

~

~
w
a:
a:

10

100

I I

~

~r10

/10 4 5
.
10106

5 102

B2

w
~

1

,103"-

......... ...., r-

II/'....

[t. . . . .......

::>

.......
0.2 -

INDEFINITE

20

100

.....
.....
.....

~

g;

50

-. ..........

0.5

~ ::::::~ l"-

0.2

1,000
IMPULSE DURATION (~.)

w

Ul

l!II ~0~06

........

~7
~

~

~ 10

..... ............

::>

(.)

-~

~

~

0.5

0.2
20

.."......

I"--

t1~

....... b,

t-..:: ;:: b::r--

100

1,000
IMPULSE DURATION (~s)

.......
-.
....... ::-.....

::::::-- ........ I"'r.....

100

1,000
IMPULSE DURATION (~.)

~

111

2 ::

....;to

..J.!l2
-....l.,03

104
105
106

10,0000

MODEL SIZE 7mm
VSZAI - V12ZAI

yo .:;:.,

;2 ~ r---r-.

5

"Y,
2

r=~

IZ'~

-.

'-

INDEFINITE

O.S

Q~

10,0000

I I II

........ 1

~

"""",:r-....

....;;~

INDEFINITE -

20

w

w

-

-i..i ~ r"--r-.

FIGURE 13. SURGE CURRENT RATING CURVES FORV12ZA05
- V68ZA05

50

......

MODEL SIZE Smm
V12ZAOS - V6SZA05

II III

~

5
2 I--

'Y.

105
106

INDEFINITE

20

100

N.!>2

B 10 t---

-=

0.1

10,0000

MODEL SIZE 5mm
VS2ZA05 - V910ZM5

103
104

~

il!a: 20 r-.

1

Ul

-I--

-.....

(.)

t:: 10 104

200

~
200

~

~

~
10 Si.,J03

w


FIGURE 12. SURGE CURRENT RATING CURVES FOR V8ZA05

100

~~

a:
a:

......

I'--.

I IIIIII

0.1

~
...
zw

-

0.5

(J)

50

MODEL SIZE 5mm
VSZMS

100

-

I"--

b

F=r--

........
~

I.

.....
....,

r-.r-.

lQ~

IMPULSE DURATION (~s)

FIGURE 14. SURGE CURRENT RATING CURVES FORV82ZA05
- V910ZA05

FIGURE 15. SURGE CURRENT RATING CURVES FOR V8ZA1V12ZAI

9-100

ZA Series

Pulse Rating Curves (Continued)
500
200
100

,1

2 - 1-;104 5
·
10106

~

-

102
~
....z 50
Sl..03
w
a: 20
a:
-t---

7~

w

-

a:
=>

rn

./..

....

zt.V.....

=> 10

0

Cl

r-c. "-.

2 I-

MODEL SIZE 7mm
V18ZAl - V68ZA2

r-::--

~ ;::r:::

i"-_

INDEFINITE

~

0.5
0.220

100

1,000
IMPULSE DURATION (~.)

10,000

FIGURE 16. SURGE CURRENT RATING CURVES FOR V18ZA 1 V68ZA2

100

200
100

~

4
/0 5

·

102
~
....
50
z
~3"-w
a: 20
a:

=> 10
w
Cl
a:
=>
rn
0

2

-

7~

0.220

100

a:
=>

~

1,000

~ 500

....
z

5

w
a: 200
a:
=>
0 100
w
Cl
a: 50
=>
rn
20
10

<
~

§

~

10,000

~

r.::: ~~

:"'-...

~ :-::::1'

-..:::--;: -..

INDEFINITE

:::::-.

-r---;

III

"

100

1,000
IMPULSE DURATION (~.)

~1

~
200 102

............

0 :,(1:1-

w
a: 50
a:
r-.
=>
0
--I---

~

w

20

a:
=>

10

rn

~ ~ ......

/

103
104
105
10·

I"'-r-...
«
;:- 100
z

.........

5

t-

F

1t...

-

Ft:::;::-

MODEL SIZE 14mm
V18ZA3· V68ZA10

:-...,.

t---... t-.... .....

INDEFINITE
~

I II III
120

100

100

.......

.......... I""'--

2
1,000
10,000
IMPULSE DURATION (~o)
FIGURE 20. SURGE CURRENT RATING CURVES FORV82ZA4·
V180ZA5

10,000

1,000
IMPULSE DURATION (flO)

10,000

FIGURE21. SURGE CURRENT RATING CURVES FORV18ZA3V68ZA10

9-101

a:

I/)

01-

500

141 I II

Cl

-..

~ [y. J"-

FIGURE 19. SURGE CURRENT RATING CURVES FOR V18ZA2·
V68ZA3
1,000

N' ~r--

~ INDEFIN:TE

...... r,.( /

r-:f:=,:

120

MODEL SIZE 10mm
V82ZA4 • V180ZA5

JII

":'-i:"-

...... t---

II III

10 5
flO 6
·
/,10

10

104
105
106

~

rn

t==::: :;::t--

.ILl L
I

20

~ 10

1-.-

5,000

21"-

~
i"

Cl

1,000
IMPULSE DURATION (flO)

-s.

200

MODEL SIZE 10mm
V18ZA2 - V68ZA3

~ 50 !'-l03

t::-......

FIGURE 18. SURGE CURRENT RATING CURVES FOR V8ZA2·
V127ZA2

2,000

-...!.

~100 102.....
....
z

---

0.5

500

1010•

)"""j ~

INDEFINITE

1,000

MODEL SIZE 10mm
V8ZA2 - V12ZA2

~.

10,000

FIGURE 17. SURGE CURRENT RATING CURVES FOR V82ZA2·
V18ZAl

500

~

1,000
IMPULSE DURATlON (~o)

I- U
1/):::1

-0

a:O
~g:

ZA Series
Pulse Rating Curves (Continued)
5,000
2,000

g

...z

1,000

u

w

CJ

a:

:::I

'"

MODEL SIZE 14mm
V82ZA12· V180ZA10

~

,....,
100

5

2
20

...z

106

....

INDEFINITE

---

200

w

~1
..,),0
~02

.........

10 3

:--... ..............

;::s::: :3::: :;:~

100
1,000
IMPULSE DURATION (~s)

~

20

'"

10 ;;:;t;EFINITE
5
2
20

10,000

FIGURE 22. SURGE CURRENT RATING CURVES FOR V82ZA 12
• V180ZA10

,...

a:

:::I

106

.......

........

~

w
CJ

.....

MODEL SIZE 14mm
V18ZA40 • V36ZA80

a: 100
a:
:::I
u 50 ~5

-.....J r,(y.

t-

10

500

g

~104105

50
20

1,000

102
103

500

w
r-..
a: 200
a:

:::I

2,000

1"s:1

---

100

r-2:

~
..............

~ r-

1,000
IMPULSE DURATION (~s)

10,000

FIGURE 23. SURGE CURRENT RATING CURRENT FOR
V18ZA40 • V36ZA80

NOTE: If pulse ratings are exceeded, a shift of VN(DC) (at specified current) of more than ±10% could result. This type of shift, which normally
results in a decrease of VN(DC), may result in the device not meeting the original published specifications, but it does not prevent the
device from continuing to function, and to provide ample protection.

9-102

ZA Series
Tape and Reel Specifications

Tape And Reel Data
• Conforms to ANSI and EIA specifications
• Can be supplied to IEC Publication 286-2
• Radial devices on tape are supplied with crimped
leads, straight leads, or under-crimped leads

CRIMPED LEADS

"zr

STRAIGHT LEADS
"ZS·

UNDER-CRIMPED
LEADS "zu·

MODEL SIZE
SYMBOL

PARAMETER

P

Pitch of Component

Po

Feed Hole Pitch

PI

Feed Hole Center to Pitch

P2

Hole Center to Component Center

F

Lead to Lead Distance

dh

Component Alignment

W

Tape Width

Wo

Hold Down Tape Width

WI

Hole Position

W2

Hold Down Tape Position

5mm
12.7±1.0
12.7 ± 0.2

7mm
12.7± 1.0
12.7 ± 0.2

10mm
25.4 ± 1.0
12.7 ± 0.2

3.85 ± 0.7
6.35 ± 1.0
5.0 ± 1.0
2.0 Max
18.0+ 1.0
18.0 - 0.5
6.0 ± 0.3
9.0 + 0.75
9.0 - 0.50

3.85 ± 0.7
6.35 ± 1.0
5.0 ± 1.0
2.0 Max
18.0 + 1.0
18.0 - 0.5
6.0 ± 0.3
9.0 + 0.75
9.0 - 0.50

2.6 ± 0.7
6.35 ± 1.0
7.5 ± 1.0
2.0 Max
18.0+1.0
18.0 - 0.5

0.5 Max
18.0 + 2.0
18.0 - 0.0

L

Length of Clipped Lead

0.5 Max
18.0 + 2.0
18.0 - 0.0
16.0 ± 0.5
29.0 Max
4.0 ± 0.2
0.7 i 0.2
11.0 Max

dP

Component Alignment

3° Max

H

Height from Tape Center to Component Sase

Ho

Seating Plane Height

HI

Component Height

Do

Feed Hole Diameter

t

Total Tape Thickness

NOTE: DimenSions are In mm.

9-103

20mm

16.0 ± 0.5
29.0 Max
4.0 ± 0.2
0.7 ± 0.2
11.0 Max

0.5 Max
18.0 + 2.0
18.0 - 0.0
16.0 ± 0.5
29.0 Max
4.0 ± 0.2
0.7 i 0.2
11.0 Max

14mm
25.4± 1.0
12.7 ± 0.2
2.6± 0.7
6.35 ± 1.0
7.5± 1.0
2.0 Max
18.0 + 1.0
18.0 - 0.5
6.0± 0.3
9.0 + 0.75
9.0 - 0.50
0.5 Max
18.0 + 2.0
18.0 - 0.0
16.0 ± 0.5
29.0 Max
4.0 ± 0.2
0.7i 0.2
11.0 Max

25.4 ± 1.0
12.7 ± 0.2
2.6 ± 0.7
6.35 ± 1.0
7.5 ± 1.0
2.0 Max
18.0 + 1.0
18.0 - 0.5
12.0 ± 0.3
9.0+ 0.75
9.0 - 0.50
0.5 Max
18.0 + 2.0
18.0 - 0.0
16.0 ± 0.5
29.0 Max
4.0± 0.2
0.7i 0.2
12.0 Max

3° Max

3° Max

3° Max

3° Max

6.0 ± 0.3
9.0 + 0.75
9.0 - 0.50

a:CJ)
011-0
CJ):::I
-0
a:O

~~

ZA Series'
Tape and Reel Ordering Information

SHIPPING QUANTITY

Crimped leads are standard on ZA types supplied in tape
and reel and are denoted by the model letler "T'. Model letter "S" denotes straight leads and letler "U" denotes special
under-crimped leads.
Example:
STANDARD
MODEL

CRIMPED
LEADS

V18ZA3

V18ZT3

UNDERCRIMPED
LEADS

STRAIGHT
LEADS
V18ZS3

V18ZU3

SIZE

RMS
(MAX)
VOLTAGE

QUANTITY PER REEL
"T" REEL

"S" REEL

"U" REEL

5mm

All

1000

1000

1000

7mm

All

1000

1000

1000
1000

lOmm

All

1000

1000

14mm

<300V

500

500

500

14mm

;,300V

500

500

500

20mm

<300V

500

500

500

20mm

;,300V

500

500

500

Packaging
VARISTOR MODEL SIZE

t0D~T
A

~~

0b ..

-- _1.

25.4
(1.00)
MIN

el-1 e~--L
.l( $)
Til)

T

SYMBOL

VOLTAGE
MODEL

A

00

MIN

MAX

MIN

MAX

MIN

MAX

MIN

MAX

All

6
(0.236)

10
(0.394)

7.5
(0.295)

12
(0.472)

10
(0.394)

16
(0.630)

13.5
(0.531)

20
(0.787)

17.5
(0.689)

26.5
(1.043)

All

6
(0.236)

7
(0.276)

7.5
(0.295)

9
(0.354)

10
(0.394)

12.5
(0.492)

13.5
(0.531)

17
(0.669)

17.5
(0.689)

23
(0.906)

4
6
(0.157) (0.236)

4
(0.157)

6
(0.236)

6.5
(0.256)

8.5
(0.335)

6.5
(0.256)

8.5
(0.335)

1
(0.039)

3
(0.118)

1
(0.039)

3
(0.118)

1
(0.039)

3
(0.118)

1
(0.039)

3

1

3

(0.118)

(0.039)

(0.118)

V68ZAVl00ZA

1.5
(0.059)

3.5
(0.138)

1.5
(0.059)

3.5
(0.138)

1.5
(0.059)

3.5
(0.138)

1.5
(0.059)

3.5
(0.138)

NA
(NA)

NA
(NA)

V120ZAV180ZA

1
(0.039)

3
(0.118)

1
(0.039)

3
(0.118)

1
(0.039)

3
(0.118)

1
(0.038)

1
(0.118)

NA
(NA)

NA
(NA)

V220ZAV910ZA

1.5
(0.059)

3.5
(0.138)

-

-

-

-

-

-

-

-

-

5
(0.197)

-

e,

V8ZA-V56ZA

V8ZA-V56ZA
V68ZAVl00ZA

5
(0.197)

-

V220ZAV910ZA
All

5
(0.197)

5.6
(0.220)

5.6
(0.220)

5
(0.197)

5
(0.197)

-

-

5.6
(0.220)

5.6
(0.220)

-

5.6
(0.220)

0.585
(0.023)

0.685
(0.027)

0.685
(0.027)

0.76
(0.030)

0.86
(0.034)

V120ZAV180ZA

0b

20mm

MAX

All

E

14mm

10mm

MIN

e
(Note
1)

E

7mm

Smm

0.585
(0.023)

5.6
(0.220)
5
(0.197)

NOTE: Dimensions in millimeters, inches in parentheses.
1. 10mm ALSO AVAILABLE; See Ordering Information.
V24ZA50 only supplied with lead spacing of 6.35mm ± 0.5mm (0.25 ± 0.197)

9-104

5
(0.197)

-

-

0.76
(0.030)

5.6
(0.220)
5
(0.197)

6.5
8.5
(0.256) (0.335)
(Note 1) (Note 1)

-

-

5
(0.197)
5.6
(0.220)
5
(0.197)

5.6
(0.220)

5.6
(0.220)

0.86
(0.034)

0.76
0.86
(0.030) (0.034)

ZA Series
Available Lead Style
Radial lead types can be supplied with a preformed crimp in
the leads, and are available in all model sizes. Lead trim
(LTRIMl is supplied to the dimensions shown.

Tn

·SEATING......
PLANE

I

.~-L
TLTRIM

·Seating plane interpretation per IEC-717
CRIMPED AND TRIMMED LEAD

VARISTOR MODEL SIZE

Smm
SYMBOL

MIN

A

-

LTRIM

2.41
(0.095)

7mm
MAX

MIN

13.0
(0.512)
4.69
(0.185)

MIN

MAX

15
(0.591)
2.41
(0.095)

14mm

10mm
MAX

MIN

19.5
(0.768)

4.69
(0.185)

2.41
(0.095)

4.69
(0.185)

20mm
MAX

MIN

2.41
(0.095)

4.69
(0.185)

MAX
29.0
(1.142)

22.5
(0.886)
2.41
(0.095)

4.69
(0.185)

NOTE: Dimensions in millimeters, inches in parentheses.

Ordering Information
• For crimped and trimmed lead styles, standard radial type
model numbers are changed by replacing the model letter
"A" with "C".

• For 101±lmm lead spacing on 20mm diameter models
only; append standard model numbers by adding "Xl 0".

Example:

Example:

STANDARD CATALOG
MODEL

ORDER AS:

STANDARD CATALOG
MODEL

ORDER AS:

V18ZA3

V18ZC3

V18ZA40

V18ZA40X10

• For crimped leads without trimming and any variations to
the above, contact Harris Semiconductor Power Marketing.

a: en

O~

~()
en;:)
-0
a:O

~g:

9-105

TV

10
SURGECTOR PRODUCTS

PAGE
SURGECTOR PRODUCT SELECTION GUiDE........ . . . . ... . . .. . . . .... .... . ... . . . .. . .. . .. . . .. . .

10-2

SURGECTOR PRODUCT DATA SHEETS
SGT03U 13,
SGT06U13,
SGT23U13

Unidirectional Transient Surge Suppressors (SURGECTORTM) . . . . . . . . . . . . . . . . . . . . . . . . . . .

10-3

SGT10Sl0,
SGT27S10

Gate Controlled Unidirectional Transient Surge Suppressors (SURGECTORTM).. ... . . . . . .. ..

10-6

SGT21B13,
Bidirectional Transient Surge Suppressors (SURGECTORTM) . . . . .. . . . .. . .. . . .. . .. ... .. . .
SGT21B13A,
SGT22B13,
SGT22B13A,
SGT23B13,
SGT23B13A,
SGT27B13,
SGT27B13A,
SGT27B13B

10-10

SGT23B27,
Bidirectional Transient Surge Suppressors (SURGECTORTM) . . . . . . . . .. . . . . .. . .. . . . . . .. ..
SGT27B27,
SGT27B27A,
SGT27B27B

10-14

SGT27S23

10-18

Gate Controlled Unidirectional Transient Surge Suppressor (SURGECTORTM)... .. . . . . . . . . . .

a:cn

~I­

uU
w::l

ClO
a: O

SURGECTORTM is a trademark of Harris Semiconductor

::I

a:

(JIll..

10-1

Surgector Product Selection Guide

PART NUMBER

FUNCTION

V2 MIN
(V)

V BO MAX
(100V/l1s)

IrSM
(1 x 211S)

IrSM
(lOx lOOOl1s)

IH
(mA)

PACKAGE
STYLE

SGT10Sl0 (Note 1)

VARCLAMP

100

Note I

300

100

> 100

A

SGT27SI0 (Note I)

VARCLAMP

270

Note I

300

100

> 100

A

SGT27S23 (Note I)

VARCLAMP

270

Note 1

300

100

> 230

A

SGT03UI3

UN I-DIRECTIONAL

30

< 50

300

100

> 130

B

SGT06U13

UN I-DIRECTIONAL

60

< 85

300

100

> 130

B

SGT23U13

UNI-DIRECTIONAL

230

< 275

300

100

> 130

B

SGT21B13

BI-DIRECTIONAL

210

270

300

100

>130

B

SGT21B13A

BI-DIRECTIONAL

210

290

300

100

>130

B

SGT22BI3

BI-DIRECTIONAL

220

280

300

100

>130

B

SGT22B13A

BI-DIRECTIONAL

220

290

300

100

>130

B

SGT23B13

BI-DIRECTIONAL

230

290

300

100

>130

B

SGT23B13A

BI-DIRECTIONAL

230

315

300

100

>130

B

SGT27BI3

BI-DIRECTIONAL

270

345

300

100

>130

B

SGT27B13A

BI-DIRECTIONAL

270

360

300

100

>130

8

SGT27B13B

BI-DIRECTIONAL

270

375

300

100

>130

B

SGT23B27

BI-DIRECTIONAL

230

290

600

200

>270

B

SGT27B27

BI-DIRECTIONAL

270

345

600

200

>270

B

SGT27B27A

BI-DIRECTIONAL

270

360

600

200

>270

B

SGT27B27B

BI-DIRECTIONAL

270

375

600

200

>270

B

NOTES:
1. Dependent on trigger circuit.
All finalized devices UL recognized to 4978 - File Number E13501o.

10-2

SGT03U13, SGT06U13
SGT23U13

HARRIS
SEMICONDUCTOR

Unidirectional Transient Surge Suppressors
(SURGECTORTM)

August 1993

Features

Applications

• Clamping Voltages: 33V, 60V, or
230V

• Telecommunications Equipment

• Peak Transient Surge Current:
300A
• Minimum Holding Current: 130mA

• Data and Communication Links
• Computer Modems
• Alarm Systems

• Subnanosecond Clamping Action
CATHODE

• Low On-State Voltage
• UL Recognized File #E135010 to
STD4978

MODIFIED TO-202

Description
These SURGECTOR devices are designed to protect telecommunication equipment, data links, alarm systems, power
supplies and other sensitive electrical circuits from damage
by switching transients, lightning strikes, load changes, commutation spikes and line crosses.
These SURGECTOR devices are monolithic compound
structures consisting of a thyristor whose gate region contains a special diffused section which acts as a zener diode.

Absolute Maximum Ratings

This zener diode section permits anode voltage turn-on of
the structure. Initial clamping by the zener diode section and
fast turn-on by the thyristor, provide excellent voltage limiting
even on very fast rise time transients. The thyristor also features very high holding current allowing the SURGECTOR to
recover to its high impedance off state after a transient. The
SURGECTOR device's normal off-state condition in the forward blocking mode is a high impedance, low leakage state
that prevents loading of the line.

(Tc = +25°C)
SGT03U13

SGT06U13

SGT23U13

UNITS

V OM •••••••••••••••••.••••••••••••••••••••••••••••••

30

VRM ••••••••••••••••••••••• •• • ••••••••• • •• ••••••••• •
Transient Peak Surge Current: .......•.................. IrsM
11lS x 21lS (Note 1) ..............•.....•......•..•.....
8J.ls x 201lS ....•.•...•..................•.....•...•..
lOllS x 560J.ls ....................................... .
lOllS x 10001lS ...................................... .
One Half Cycle ......................... 50 - 60Hz (Note 2)
One Second ..........•..........•... 50 - 60Hz, Hallwave

58
1

225
1

V
V

300
200
125
100
60
30

300
200
125
100
60
30

300
200
125
100
60
30

A
A

Continuous Off State Voltage:

A
A
A
A

a:CJ)

01I-U

U:::>

Wo

Operating Temperature (TA) •••••••••••••••••••••••••••••••

-40°C to +85°C

°C

C)o

Storage Temperature Range (TSTG )'

-40°C to +150°C

°C

~Q.

••••••••••••••••••••••••

a: a:

NOTES:
1. Unit designed not to fail open below: 450A
2. One every 30 seconds maximum.

Equivalent Schematic Symbols

~
~
SURGECTOR'M is a trademark of Harris Semiconductor.

~

-r

CAUTION: These devices are sensitive to electrostatic discharge. Users should follow proper I.e. Handling Procedures.
Copyright © Harris Corporation 1993

10-3

+
J.
File Number

1692

Specifications SGT03U13, SGT06U13, SGT23U13
Electrical Characteristics At Case Temperature (Tc = +:25°C), Unless Otherwise Specified
PARAMETER

TEST
CONDITIONS

SYMBOL

Off-State CUrrent

IRf.1

Clamping Voltage
SGT03U13
SGT06U13
SGT23U13

Vz

Breakover Voltage
SGT03U13
SGT06U13
SGT23U13
Holding Current
On-State Voltage

Voo

Main Terminal Capacitance

Co

SGT10Sl0
TYP

Maximum Rated VOM
TA = +25°C
TA = +85°C
VAM = tV
TA =+25°C
TA = +85°C

10M

Reverse Current

MIN

MAX

UNITS

50
10

IIA

1
10

mA
mA

nA

Iz = l0011A
33

V
V
V

60

230
dv/dt = 100V/IiS

50
85
275
130

IH
VT

2

IT= lOA
90

V
V
V
mA
V
pF

Performance Curves
275
250

-I-- -

225
IT

€

200

~
~

175

z

125

::0

100

0

75

w

CJ

Vao

ii:
rnA

~

150

50

v

1.5

VOM

r--r--r-,-r--,-",-,""-,.--,---,-r--r-.

I

I

I

I

275

I

€

~ 1.2 r-+-t-~~_t-+-+--ff-+-+-I-I--I--l

~-

225

~ 175
0
> 150
a:

I"

w

~

..................

0.9 r-+-t---f-t-+-+--f~+-'"",,,od-t-+-l

125

..:
w 100

............ ""-

a:

~ 0.8 I--I--+--f-t-+-+--ff-+-+-I_~I~~--l

III

::0

g;z 0.7

I I

w 200

15
.........
51'0r-+-t---f-t-+-f~~+--r--f-t-+-l

til

I

SGT23U13

CJ

~ 1.1 r-+--+~-~d--+~~+--+~-r-+-~

N

II

250

ffi 1.3r-~~~r-+-t---f~+-+-+-t-+-r-i-;

:c

t:r;~~;±;~~;±~~tS:GIT:03~Uel:3t::t:t:jt:I:j

AMBIENT TEMPERATURE (OC)
FIGURE 2. TYPICAL CLAMPING VOLTAGE vs TEMPERATURE

.§. 1.4 p.,d--t---f-t-+-+--fr-- IT(INITIAL)=2A -

o

SGT06U13
I
I

25
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90

FIGURE 1. TYPICAL VOLT-AMPERE CHARACTERISTICS

<

~13 )-;--t--t--t-J

I--I--+--f-t-+-+--ff--I-+-I-I--I--l

SGT06UI3

75
50
25

0.6 L..--'---'---'_"---'-......--''---'--'---'_''---'--'
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90
AMBIENT TEMPERATURE ("C)
FIGURE 3. TYPICAL HOLDING CURRENT vs TEMPERATURE

10-4

10

100
1,000
RATE OF RISE OF VOLTAGE (V1~s)
FIGURE 4. TYPICAL Vao vs dv/dt

10,000

SGT03U13, SGT06U13, SGT23U13
Terms and Symbols
V OM (Maximum Off-State Voltage) - Maximum off-state voltage (DC or peak) which may be applied continuously.
V RM (Maximum Reverse Voltage) - Maximum reverse· blocking voltage (DC or peak) which may be applied.
' TSM (Maximum Peak Surge Current) - Maximum nonrepetitive current which may be allowed to flow for the time state.

TA (Ambient Operating Temperature) - Ambient temperature
range permitted during operation in a circuit.
T STG (Storage Temperature) - Temperature range permitted
during storage.
10M (Off-State Current) - Maximum value of off-state current
that results from the application of the maximum off-state
voltage (V OM ).

IRM (Reverse Current) - Maximum value of reverse current
that results from the application of the maximum reverse
voltage (V RM ).

V z (Clamping Voltage) - off-state voltage at a specified current.
Veo (Breakdown Voltage) - voltage at which the device
switches from the off-state to the on-state.

'H

(Holding Current) - Minimum on-state current that will hold
the device in the on-state after it has been latched on.
V T (On-State Voltage) - Voltage across the main terminals
for a specified on-state current.
Co (Main Terminal Capacitance) - Capacitance belween the
main terminals at a specified off-state voltage.

Packaging
TO·202 Modified
2 LEAD JEDEC STYLE T0-202 SHORT TAB PLASTIC PACKAGE

ACTIVE ELEMENT

INCHES

iji

MILLIMETERS
NOTES

SYMBOL

MIN

MAX

MIN

MAX

A

0.130

0.150

3.31

3.81

-

b

0.024

0.028

0.61

0.71

2,3
1,2,3

b1

0.045

0.055

1.15

1.39

b2

0.270

0.280

6.86

7.11

c

0.018

0.022

0.46

0.55

1,2,3

D

0.320

0.340

8.13

8.63

-

E

0.340

0.360

8.64

9.14

e1

0.200 sse

5.08

sse

4

H1

0.080

0.100

2.04

2.54

-

J1

0.035

0.045

0.89

1.14

5

L

0.410

0.440

10.42

11.17

-

0.110

-

2.79

1

L1

er m
~JUU
w::::l
ClO
a: O
::::I

a:

me..
NOTES:

1.
2.
3.
4.

Lead dimension and finish uncontrolled in L1.
Lead dimension (without solder).
Add typically 0.002 inches (0.05mm) for solder coating.
Position of lead 10 be measured 0250 inches (6.35mm) from bottom
of dimension D.
5. Position of lead to be measured 0.1 00 inches (2.54mm) from bottom
of dimension D.
6. ContrOlling dimension: Inch
7. Revision 1 dated 1-93.

10-5

SGT10S10
SGT27S10

HARRIS
SEMICONDUCTOR

Gate Controlled Unidirectional Transient
Surge Suppressors

August 1993

Description

Applications

• Blocking Voltage 100V and 270V

• Telecommunications Equipment

• Peak
300A

• Data and Voice Lines

Transient

Surge

Current

• Computer Modems

• Minimum Holding Current 100mA

• Alarm Systems

• Subnanosecond Clamping Action
• Low On-State Voltage

• UL Recognized File # E135010 to
STD497B

MODIFIED TO-202

Description
SURGECTOR transient surge protectors are designed to
protect telecommunication equipment, data links, alarm systems, power supplies, and other sensitive electrical circuits
from damage that could be caused by switching transients,
lightning strikes, load changes, commutation spikes, and line
crosses.
These devices are fast turn-on, high holding current thyristors. When coupled with a user supplied voltage level detec-

Absolute Maximum Ratings

(Tc

tor, they provide excellent voltage limiting even on very fast
rise time transients. The high holding current allows this
SURGECTOR to return to its high impedance off state after
a transient.
The SURGECTOR device's normal off-state condition in the
forward blocking mode is a high impedance, low leakage
state that prevents loading of the line.

=+25°C)
SGT10S10

SGT27S10

UNITS

100
1

270
1

V
V

300
200
125
100
60
30

300
200
125
100
60
30

A
A
A
A
A
A

Continuous Off State Voltage:
V OM •••••••••••• •••••••••••••••••••••••••••••••••••••••••••••••••••••••••

VRM ···································································· .
Transient Peak Surge Current: ...... , ........................................ ' TSM
lJ.ls x 2J.ls (Note 1) ........................................................ .
SJ.lS x 20J.lS .............................................................. .
10J.lS x 560J.ls ............................................................ .
10J.ls x 1000J.lS ........................................................... .
One Hall Cycle, 1 every 30 seconds .....................................50 - 60Hz
One Second, Hallwave ...............................................50 - 60Hz

Operating Temperature (TA) •.........•................•..•..•••......•.....•..•

-40°C to +S5°C

°C

Storage Temperature Range (Tsm) ............................................. .

-40°C to +150oC

°C

NOTE: 1. Unit designed not to fail open below 450A.

Equivalent Schematic Symbols

m
#,J

G~
7J.

G-t,

~

SURGECTORTM is a trademark of Harris Semiconductor.
CAUTION: These devices are sensitive to electrostatic discharge. Users should follow proper I.C. Handling Procedures.
Copyright © Harris Corporation 1993

10-6

File Number

1691

Specifications SGT10S10, SGT27S10
Electrical Characteristics

At Case Temperature (Tc = +25°C), Unless Otherwise Specified
SGT27S10

SGT10S10
PARAMETER

SYMBOL

TEST
CONDITIONS

TYP

MIN

MIN

MAX

TYP

MAX

UNITS

=

Off-State Current

VOM 100V
TA = +2SoC
TA +8SoC

nA

50
10

=

~A

V OM = 270V
TA = +2SoC
TA = +8SoC
Off-State Current

VRM
TA
TA

Breakover Voltage

Veo

=1V
=+25°C
=+85°C

dv/dt = 100V/~s

100
50

~A

1
10

1
10

rnA
rnA

100

285

V

nA

(Note 1)
Holding Current

100

On-State Voltage

IT= 10A

Gate-Trigger Current
Main Terminal
Capacitance

Co

VOM

rnA

100

=OV

2

2

V

150

150

rnA

pF
pF

90
50

V OM = 50V at 1MHz

NOTE:
1. External zener diode from anode to gate: 60V (SGT10S10); 270V (SGT27S10).

Performance Curves
~ 1.4 ,..-,---.--.----.--.--...-....---,.--,,--,-,--.-,-,.--,,

ffi~ 13"""
. f-"'+,-+-+-+-+-+-+-+-+IT

8

1.2

1--+--f"""';1-+-+-+-+--f-+-+--f-+--i
,

ffi

1.1

I--+-+-+--P"'d--+-+-+-+--+-i-+--I

~ 1.0

~

0.9

I--+--f-+-+-+--f"d-r-....--f-+-+--f-+--i
I--+--f-+-+-+-+-+--f"""".l-+--f-+--i

w 0.8

I--+-+-+-+-+-+-+-i-+--+"""',..-+--I
.....

:§

0.7

I-+-++-+-f-t--I-+-+-+-fl---j
. . . 1-=1'-.=-1

oz

0.6 L-....L...--l._.l..-....L...--L_.l..-....L...--'_.l..-.....L..--'_-'-...J

g
VBO

!;;:

rnA

~

lou

a:

____________ ..... __________ '55

I"-

"

-40 -30 -20 -10

v

Vo = 30V -

!E

0

10

20 30

~

40 50 60 70 80

AMBIENT TEMPERATURE (OC)

FIGURE 1. TYPICAL VOLT-AMPERE CHARACTERISTICS

FIGURE 2. NORMALIZED GATE-TRIGGER CURRENT vs
TEMPERATURE

10-7

90

O::(J)

Ott-O

0::1

We

ClO
0:: a:;
ijlo..

SGT10S10, SGT27S10
Performance Curves (Continued)
1.5

I

11.4
...
z

I\-

U

CI 1.1
z

1
!z
w
a:
a:
CI

r....

z

~

:c
cw 0.9
N
:::;

60V (SGT1 OSl 0); 270V (SGT27S10)
1.25

o

r"\

90 1.0
«

EXTERNAL ZENER DIODE FROM ANODE TO GATE

IT (INITIAL) = 2A -

~

1.3

w
a:
a: 1.2
::>

1.50

I I I I

r-...

0.8

~
:c

.... ~!-

1.00

-

c

...... t.....

~

:::!
a:
0 0.7
z

0.75

~

0.6

0.50
40 -30 -20 -10

0

10

20 30

40

SO 60 70

80

90

10

AMBIENT TEMPERATURE (Oc)

100

1,000

10,000

RATE OF RISE OF VOLTAGE (VII'S)

FIGURE 3_ NORMALIZED HOLDING CURRENT va
TEMPERATURE

FIGURE 4. NORMALIZED VBO vs dv/dt

Terms and Symbols
V OM (Maximum Off-State Voltage) - Maximum off-state voltage (DC or peak) which may be applied continuously.
V RM (Maximum Reverse Voltage) - Maximum reverse-blocking voltage (DC or peak) which may be applied.
ITSM (Maximum Peak Surge Current) - Maximum nonrepetitive current which may be allowed to flow for the time state.
TA (Ambient Operating Temperature) - Ambient temperature
range permitted during operation in a circuit.
T STG (Storage Temperature) - Temperature range permitted
during storage.

IRM (Reverse Current) - Maximum value of reverse current
that results from the application of the maximum reverse
voltage (V AM ).

IH (Holding Current) - Minimum on-state current that will hold
the device in the on-state after it has been latched on.
V T (On-State Voltage) - Volta,ge across the main terminals
for a specified on-state current.
IGT (Gate-Trigger Current) - Minimum gate current which will
cause the device to switch from the off-state to the on-state.

Co (Main Terminal Capacitance) - Capacitance between the
main terminals at a specified off-state voltage.

10M (Off-State Current) - Maximum value of off-state current
that results from the application of the maximum off-state
voltage (VOM)'

10-8

SGT10S10, SGT27S10
Packaging
TO-202 Modified

ACTIVE ELEMENT

Ib2;~

ir l -'-T

3 LEAD JEDEC STYLE T0-202 SHORT TAB PLASTIC PACKAGE

rJI

INCHES

0

h- I

L

I~I

II-- I

1

i-b

I

2

3

--e
I--- el - -

r-

1

'-t
-+i

Jl

~

MILLIMETERS

SYMBOL

MIN

MAX

MIN

A

0.130

0.150

3.31

3.81

MAX

NOTES

-

b

0.024

0.028

0.61

0.71

2,3

b1

0.045

0.055

1.15

1.39

1,2,3

b2

0.270

0.280

6.86

7.11

-

c

0.018

0.022

0.46

0.55

1,2,3

D

0.320

0.340

8.13

8.63

-

E

0.340

0.360

8.64

9.14

-

e

0.100TYP

2.54 TYP

4

el

0.2009SC

5.089SC

4

2.04

2.54

HI
J1

0.080

0.100

0.035

0.045

0.89

1.14

L

0.410

0.440

10.42

11.17

-

Ll

-

0.110

2.79

1

5

( o oj
0

I---E---I
NOTES:
1. Lead dimension and finish uncontrolled in L 1•
2. Lead dimension (without solder).
3. Add typically 0.002 inches (0.05mm) for solder coating.
4. Position of lead to be measured 0250 inches (6.35mm) from bottom
of dimension D.
5. Position of lead to be measured 0.1 00 inches (2.54mm) from bottom
of dimension D.
6. Controlling dimension: Inch
7. ReviSion 1 dated 1-93.

OCcn

~I­
UU
w::J

ClC
ocO

::JOC

cna.

10-9

SGT21813, SGT21813A, SGT22813,

I-lARRiS SGT22813A, SGT23813, SGT23813A,
SEMICONDUCTOR

SGT27813, SGT27813A, SGT278138
Bidirectional Transient Surge Suppressors
(SURGECTORTM)

August 1993

MT2

Features

Applications

• Clamping Voltage ••••••• 210V, 220V,
230V and 270V

• Data and Communication Links
• Computer Modems

• Peak Transient Surge Current •• 300A

• Alarm Systems

• Minimum Holding Current .•• 130mA
• Continuous Protection
MT1

MODIFIED TO·202

• Low On State Voltage
• UL Recognized
STD 4978

File #E135010 to

Description
These SURGECTOR devices are designed to protect telecom·
munication equipment, data links, alarm systems, power supplies and other sens~ive electrical circu~s from damage by
switching transients, lightning strikes, load changes, commuta·
tion spikes and line crosses.

Initial clamping by the zener diode section, and fast turn on
by the thyristor, provide excellent voltage lim iting even on
very fast rise time transients. The thyristor also features very
high holding current, which allows the SURGECTOR to
recover to its high impedance off state after a transient.

Bidirectional SURGECTOR devices are constructed using two
monolithic compound chips each consisting of a thyristor whose
gate region contains a special diffused section which acts as a
zener diode. This chips are connected in anti parallel, providing
bidirectional protection. This zener diode section permits anode
vottage turn on of the structure.

All these devices are supplied in a 2 lead, modified TO·202
VERSATAB package.

Absolute Maximum Ratings (Tc = +25°C)
SGT21BI3
SGT21B13A

SGT22B13
SGT22B13A

SGT23B13
SGT23B13A

SGT27B13
SGT27B13A
SGT27B13B

UNITS

185
185

190
190

200
200

235
235

V
V

300
300
200
200
125
125
100
100
60
60
30
30
-40oC to +85°C
·40oC to + 150°C

A
A
A
A
A
A
°C
°C

Continuous Off State Voltage:
VOM

••••·••••·•••••••••••••••••••••••·•••••• ••

V RM ·····················••·················· .

Transient Peak Surge Current ................... IrsM
II'S x 21'S (Note 1) ............................. .
81'S x 201'5 ................................... .
10~s x 560~s ................................. .
101'5 x 10001'5 ................................ .
One Half Cycle .................. 50 • 60Hz (Note 2)
One Second ...................50 . 60Hz, Hallwave
Operating Temperature (TA) ••••••.•••••••••.••.•••••
Storage Temperature Range (TsrG)' ................. .
NOTES:
1. Unit designed not to fail open below: 450A.
2. One every 30 seconds maximum.

300
300
200
200
125
125
100
lOa
60
60
30
30
·40oC to +85°C
-40°C to + 150°C

Equivalent Schematic Symbols

~2

~1

d:
I.Tl

-J;

1:1

SURGECTOR'M is a trademark of Harris Semiconductor
CAUTION: These devices are sensitive to electrostatic discharge. Users should follow proper I.C. Handling Procedures.
Copyright © Harris Corporation 1993

10·10

File Number

1895.2

Specifications SGT2XB13, SGT2XB13A, SGT27B13B
Electrical Characteristics At Case Temperature (Tc = +25°C), Unless Otherwise Specified

PARAMETER
Off-State Current

TEST
CONDITIONS

SYMBOL
IOM ,IRM

Clamping Voltage
SGT21B13
SGT21B13A
SGT22B13
SGT22B13A
SGT23B13
SGT23B13A
SGT27B13
SGT27B13A
SGT27B13B

Vz

Breakover Voltage
SGT21B13
SGT21B13A
SGT22B13
SGT22B13A
SGT23B13
SGT23B13A
SGT27B13
SGT27B13A
SGT27B13B

Vso

Maximum Rated YOM, VRM
TA =+25°C
TA =+85°C

MIN

LIMITS
TYP

-

-

dv/dt =100VlllS

-

-

IH

On-State Voltage

VT

Main Terminal Capacitance

Co

UNITS

200
100

nA

250
270
260
270
270
295
325
340
355

V
V
V
V
V
V
V
V
V

270
290
280
290
290
315
345
360
375

V
V
V
V
V
V
V
V
V

~

Iz <200I1A

210
210
220
220
230
230
270
270
270

Holding Current

MAX

130

=lOA
VDM =VRM =50V,
Frequency =1MHz

-

-

IT

50

mA
2

V

-

pF

Terms and Symbols
V OM (Maximum Off-State Voltage) - Maximum off-state voltage (DC or peak) which may be applied continuously.
V RM (Maximum Reverse Voltage) - Maximum reverse-blocking voltage (DC or peak) which may be applied.
ITSM (Maximum Peak Surge Current) - Maximum nonrepetitive current which may be allowed to flow for the time state.
TA (Ambient Operating Temperature) - Ambient temperature
range permitted during operation in a circuit.
T STG (Storage Temperature) - Temperature range permitted
during storage.
10M (Off-State Current) - Maximum value of off-state current
that results from the application of the maximum off-state
voltage (V OM )' .

IRM (Reverse Current) - Maximum value of reverse current
that results from the application of the maximum reverse
voltage (VRM)'

V z (Clamping Voltage) - off-state voltage at a specified current.
Vos (Breakdown Voltage) - voltage at which the device
switches from the off-state to the on-state.
1l:C/)

IH (Holding Current) - Minimum on-state current that will hold
the device in the on-state after it has been latched on.

01-

V T (On-State Voltage) - Voltage across the main terminals
for a specified on-state current.

ClO

Co (Main Terminal Capacitance) - Capacitance between the
main terminals at a specified off-state voltage.

10-11

I-u
u::l

we
cc

Il:

i7la..

SGT2XB13, SGT2XB13A, SGT27B13B

r

Performance Curves

'1

170.-_+--~--+_~~_+--~--+_--~_+--~

150K-_+--~--+_~~_+--~--;_--~_+--~

ii:'

·• ..1. . . . . . . . . . . . ..

w

~ 110~_+--~--+_~~_+--~--;_--~_+--~

\

~

. .--(,:00

mA

10M

~130~_+--~--+_~~_+--~--;_--~_+--~

~

~~~\--;-~~-+--~--~-+--~~~~

~
u

70r--f~~--+_--~_+--_r--;_--~_+--~

""'r-..

50r-_+--~~~~~_+--~--;_--~_+--~

--1'--....

30r--r~~~-i--~~--+__+=-~~
u u u _ u u __ u

____ u u _

10~~---L--~--~~---L--~--~~--~

o

V
VOM
FIGU RE 1. TYPICAL VOLT-AMPERE CHARACTERISTICS FOR
ALL TYPES

20

40

60

80
100 120 140 160 180 200
VOLTAGE (V)
FIGURE 2. TYPICAL CAPACITANCE vs VOLTAGE FOR ALL
TYPES

~
w

~

!:i

1.25 ~+~++l+\ol+-_+_++lif+H+---+-H-++-1+H

g

I

1.00

-

1-+++-++HI+"'::1=-=t-++IH-ttf-+-t-lH++ttI

w

a:

III

o

~

0.75 ~+~++l+\ol+-_+_++lif+H+---+-H-++-1+H

=-a:
o

z

0.8 ~~~__~"""--l__.1-_L--l__.1-"""~__.1-....J
-40 ·30 ·20 ·10 0 10 20 30 40 50 60 70 80 90
AMBIENT TEMPERATURE ("C)
FIGURE 3. NORMALIZED ZENER VOLTAGE vs
TEMPERATURE FOR ALL TYPES

1.7
;( 1.6

£

....
zw

1.5

a: 1.4
a:

:;)

U

CI

z

90

1.3
1.2

0.50 L--L....J....l..J..l.J.LU---l-J....L.Ju.J.I.1J..__.1-L..L.u..u.u
10,000
10
100
1,000
RATE OF RISE OF VOLTAGE (V/fIS)
FIGURE 4. NORMALIZED VBO vs dv/dt FOR ALL TYPES

r\.
I\.

"

"

'\

:z: 1.1

0

w

~

0(

=a:

0.9

z

0.8

0

................

0.7 '-.J-...L........_ _~--'---'_ _.L---'-~__.L-......~---'
-40 -30 ·20 -10 0 10 20 30 40 50 60 70 80 90
AMBIENT TEMPERATURE ("C)
FIGURE 5. NORMALIZED HOLDING CURRENT vs TEMPERATURE FOR ALL TYPES

10-12

SGT2X813, SGT2X813A, SGT278138
Packaging
TO-202 Modified

ACTIVE ELEMENT

r- b

ir l

2 --I

---.-l

1/1

Hf

I

o

h- -I

C'

I

t

2 LEAD JEDEC STYLE T()"202 SHORT TAB PLASTIC PACKAGE

rJ-1

INCHES
MIN

MAX

A

0.130

0.150

3.31

3.Bl

-

b

0.024

0.02B

0.61

0.71

2,3

b

1,2,3

I

1-1 I~bf
I

1

2

o:t,

~
0

f

MIN

MAX

NOTES

0.045

0.055

1.15

1.39

b2

0.270

0.280

6.86

7.11

-

c

0.018

0.022

0.46

0.55

1,2,3

0

0.320

0.340

8.13

8.63

E

0.340

0.360

8.64

9.14

e

f--ef --

(

MILLIMETERS

SYMBOL

f

0.200 BSC

5.08 BSC

4

H,

0.080

0.100

2.04

2.54

-

J,

0.035

0.045

0.89

1.14

5

L

0.410

0.440

10.42

11.17

-

L

-

0.110

2.79

1

f

oj

I------ E--l
NOTES:
1. Lead dimension and finish uncontrolled in Lt.
2. Lead dimension (without solder).
3. Add typically 0.002 inches (O.05mm) for solder coating.
4. Position of lead to be measured 0.250 inches (6.35mm) from bottom
of dimension D.
5. Position of lead to be measured 0.1 00 inches (2.54mm) from bottom
of dimension D.
6. Controlling dimension: Inch
7. Revision 1 dated 1-93.

a:cn
~I­

UU
w::)

<.!)C

a: O
::)a:
cne..

10-13

SGT23827, SGT27827
SGT27827A, SGT278278

HARRIS
SEMICONDUCTOR

Bidirectional Transient Surge Suppressors
(SURGECTORTM)

August 1993

MT2

Features

Applications

• Clamping Voltage •.••. 230V or 270V,

• Data and Communication Links

• Peak Transient Surge Current ..• SOOA

• Computer Modems

• Minimum Holding Current •.. 270mA

• Alarm Systems

• Continuous Protection
• Low On State Voltage

Mn

• UL Recognized File #E135010 to
STO 4978

MODIFIED TO-202

Description
These SURGECTOR devices are designed to protect telecommunication equipment, data links, alarm systems, power supplies and other sensnive electrical circuns from damage by
switching transients, lightning strikes, load changes, commutation spikes and line crosses.

Initial clamping by the zener diode section, and fast turn on
by the thyristor, provide excellent voltage limiting even on
very fast rise time transients. The thyristor also features very
high holding current, which allows the SURGECTOR to
recover to its high impedance off state after a transient.

Bidirectional SURGECTOR devices are constructed using two
monolithic compound chips each consisting of a thyristor whose
gate region contains a special diffused section which acts as a
zener diode. This chips are connected in anti parallel, providing
bidirectional protection. This zener diode section permits anode
vonage turn on of the structure.

All these devices are supplied in a 2 lead, modified TO-202
VERSATAB package.

Absolute Maximum Ratings (Tc = +25°C)

Continuous Off State Voltage:
VDM ·•••·••·•••• •• • •••••••••••••••••••••••••••••••••
VRM •••••••••••••••••• •• • •••• • •• • •• • •• • •• • •• ••••••• •
Transient Peak Surge Current .......................... IrsM
I~s x2~s (Note I) ................................... .
8~sx20~ ......................................... .
10l-ls x 560~ ....................................... .
10~x 1000~ ...................................... .
One Half Cycle ......................... 50 - 60Hz (Note 2)
One Second ......................... 50 - 60Hz, Halfwave
Operating Temperature (ToJ .............................. .
Storage Temperature Range (TSTG )' ••••••••••••••••••••••••
NOTES:
I. Unit designed not to fail open below: 900A.
2. One every 30 seconds maximum.

SGT23B27

SGT27B27
SGT27B27A
SGT27B27B

UNITS

200
200

235
235

V
V

600
400
250
200
60
30

600

A

400

A

250
200
60
30

A
A
A
A
°C
°C

-40°C to +85°C
-40oC to +150°C

Equivalent Schematic Symbols

rf£2

~2

~1

l.n

-*
~1

SURGECTOR'M is a trademark of Harris Semiconductor
CAUTION: These devices are sensitive to electrostatic discharge. Users should follow proper I.C. Handling Procedures.
Copyright

© Harris Corporation

1993

10-14

File Number

3603

Specifications SGT23B27, SGT27B27, SGT27B27A, SGT27B27B
Electrical Characteristics At Case Temperature (Tc =+25°C). Unless Otherwise Specified
PARAMETER

Off-State Current

TEST
CONDITIONS

SYMBOL
IOM.IRM

Clamping Voltage
SGT23B27
SGT27B27
SGT27B27A
SGT27B27B

Vz

Breakover Voltage
SGT23B27
SGT27B27
SGT27B27A
SGT27B27B

Veo

LIMITS
MIN

TYP

Maximum Rated VOM • VRM
TA =+25°C
TA =+S5°C
Iz < 2OOIlA
230
270
270
270

Holding Current
On-State Voltage

VT

Main Terminal Capacitance

Co

dv/dt

MAX

UNITS

200
100

nA
~

325
340
355

V
V
V
V

290
345
360
375

V
V
V
V

2

mA
V

=100VlllS

270

IH

=lOA
VOM =VRM =50V.
Frequency =1MHz
IT

SO

pF

Terms and Symbols
V OM (Maximum Off-State Voltage) - Maximum off-state voltage (DC or peak) which may be applied continuously.
V AM (Maximum Reverse Voltage) - Maximum reverse-blocking voltage (DC or peak) which may be applied.
ITSM (Maximum Peak Surge Current) - Maximum nonrepetitive current which may be allowed to flow for the time state.
TA (Ambient Operating Temperature) - Ambient temperature
range permitted during operation in a circuit.
T STG (Storage Temperature) - Temperature range permitted
du ring storage.
10M (Off-State Current) - Maximum value of off-state current
that results from the application of the maximum off-state
voltage (V OM ).

lAM (Reverse Current) - Maximum value of reverse current
that results from the application of the maximum reverse
voltage (V AM ).
V z (Clamping Voltage) - off-state voltage at a specified current.
VOB (Breakdown Voltage) - voltage at which the device
switches from the off-state to the on-state.
IH (Holding Current) - Minimum on-state current that will hold
the device in the on-state after it has been latched on.
V T (On-State Voltage) - Voltage across the main terminals
for a specified on-state current.
Co (Main Terminal Capacitance) - Capacitance between the
main terminals at a specified off-state voltage.

10-15

SGT23B27,· SGT27B27, SGT27B27A, SGT27B27B

Performance Curves
300r---r--r--~~---r--r--~~r---r--'

~O~-+-~-+-~--+-~-+-~~-+-~

~Or--+-~-+-~--+-~-+-~r--+-~

~210~-+-~-+-~--+-~-+-~r--+-~
w

!il150 \

<

~r+-~-+-~--+-~-+-~~-+-~

--

120 \
5
~
r-~-~-+-~--+-~-+-~r--+-~

~

90

"-

.........
H=txt::t:j:::t:::t:=t;;J

()

60
30H

20

V

40

60

80

100

120

140

160

180

200

VOLTAGE (V)

VOM

FIGURE 1. TYPICAl. VOl.T·AMPERE CHARACTERISTICS FOP!
ALL TYPES

FIGURE 2. TYPICAL CAPACITANCE vs VOLTAGE FOR ALL
TYPES

1.2 ,...-....---r-,...--r---r--r--r---r-..--r---r-..--,

1.50

r--r-r-,..,.rrr~--r--r..,...,n-rm--"'-'r-rTMnn

1.25

r--+~t+ttttt---t-++tH+ttt--~t-+tt11tt1

~
w

~

(!1

~1.1 r-;--+-r-+--t-+-+--t-t-+-+-t-~
~
~

~

~

w

,.,. ........

~

~

I!:I

~N

1

~

r-+--+~-+-+"""'''''''F~--t~-+-+-+-I.......ool
~,.
........

--

~

1.00 r--+-+-++H+I+"''''9~+tH+ttt--t-t-+tt11tt1

w
a:

--~

m

!
c

~

~ 0.9 I-~--t-+--+~r-+--+-II-+--+-II-+--+--I

a:

~

0.75 r--++t+ttttt---t-++tH+ttt--t-t-+tt11tt1

~
0.50 '---'--'-.L..I..LLJ.u.........-'-...LJu...LW-_-'--L-L.LJ.JLW
10
100
1,000
10,000

0.8 '--'--'-_'---'-......_-'---'-......_-'---'--'-_-'--...J
-40 -30 ·20 ·10 0 10 20 30 40 50 60 70 80 90
AMStENT TEMPERATURE ("C)

RATE OF RISE OF VOLTAGE (VII'S)

FIGURE 3. NORMALIZED ZENER VOLTAGE vs
TEMf"EI'IATUI'IE FOR ALL TYPES

1.7

<'
.§.

1.6

zw 1.5

0-

a: 1.4
a:
()
1.3
(!1
::>

z

15 1.2

....
0

:z: 1.1
C
w

~

«
::;

FIGURE 4. NORMALIZED V BO vs dv/dt FOR ALL TYPES

\.
\.

"\

'" '"

"

I'...

0.9

II:

0

z 0.8

, ....

i"""o- r--....

r-

0.7 '--'--'--...lL.--'--'---I_-'--'-......_.L--'---L---I
-40 -30 ·20 ·10 0 10 20 30 40 50 60 70 80 90
AMBIENT TEMPERATURE (OC)

FIGURE 5. NORMALIZED HOLDING CURRENT vs TEMPERATURE FOR ALL TYPES

10·16

SGT23827, SGT27827, SGT27827A, SGT278278
Packaging
TO-202 Modified

ACTIVE ELEMENT

r-~;~

ir l

1/

t

I

o

tt- I

L

H,

I

Ijl

INCHES

I~I

f---

MIN

MAX

A

0.130

0.150

3.31

3.81

-

b

0.024

0.028

0.61

0.71

2,3
1,2,3

b,

I

II--

1

2

·~.l"

oj

I---E---l
NOTES:
1. Lead dimension and finish uncontrolled in L, .
2. Lead dimension (without solder).
3. Add typically 0.002 inches (0.05mm) for solder coating.
4. Position of lead to be measured 0.250 inches (6.35mm) from bottom
of dimension D.
5. Position of lead to be measured 0.1 00 inches (2.54mm) from bottom
of dimension D.
6. Controlling dimension: Inch
7. Revision 1 dated 1-93.

10-17

MIN

MAX

NOTES

b,

0.045

0.055

1.15

1.39

b2

0.270

0.280

6.86

7.11

-

c

0.018

0.022

0.46

0.55

1,2,3

D

0.320

0.340

8.13

8.63

E

0.340

0.360

8.64

9.14

e,

~
0

MILLIMETERS

SYMBOL

I

i-- e , --

(

2 LEAD JEDEC STYLE T0-202 SHORT TAB PLASTIC PACKAGE

0.200 SSC

5.08BSC

4

H,
J,

0.080

0.100

2.04

2.54

-

0.035

0.045

0.89

1.14

5

L

0.410

0.440

10.42

11.17

-

L,

-

0.110

-

2.79

1

m

SGT27S23

HARRIS
SEMICONDUCTOR

Gate Controlled Unidirectional Transient
Surge Suppressor (SURGECTORTM)

August 1993

Description

Applications

• Blocking Voltage 270V
• Peak Transient
300A

Surge

• Telecommunications Equipment
Current

• Minimum Holding Current 230mA

• Data and Voice Unes
• Computer Modems
• Alarm Systems

• Subnanosecond Clamping Action
• Low On-State Voltage
• UL Recognize Rle # E135010 to
STD497B
MODIFIED TO-202

Description
SURGECTOR transient surge protectors are designed to
protect telecommunication equipment, data links, alarm systems, power supplies, and other sensitive electrical circuits
from damage that could be caused by switching transients,
lightning strikes, load changes, commutation spikes, and line
crosses.
These devices are fast turn-on, high holding current thyristors. When coupled with a user supplied voltage level detector, they provide excellent voltage limiting even on very fast

rise time transients. The high holding current allows this
SURGECTOR to return to its high-impedance off state after
a transient.
The SURGECTOR device's normal off state condition in the
forward blocking mode is a high impedance, low leakage
state that prevents loading of the line.
The SGT27S23 is supplied in a 3 lead, modified, TO-202
package.

Absolute Maximum Ratings (Tc = +250 C)
SGT27S23

UNITS

VRM •·•·••··•····•••··••··••·•··••··•····•••··•···••··• •• •·• •• ··•· •• · ••••••••

270
1

V
V

Transient Peak Surge Current:. . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. IrsM
1j!S x 21ls (Note 1) ..•...........•..............................••.......•......
Sj!S x 20j!S .•................................••..•..•...........••....•......•
10j!S x 560j!S ......................•..•..........•...•.............•..•.......
1OILS x 1oo0j!S ...•..•...•...•.....••.......•...••.....••..•.............••.•..
One Half Cycle ...•.........•.•..•.......•....•.•..•••.••....•.. 50 - 60Hz (Note 2)
One Second ..............••.........•....•.••.•...•..•..••••.50 - 60Hz, Halfwave

300
200
125
100
60
30

A
A
A
A
A
A

Operating Temperature (TA) •.••••••••••••••••••••••••••••.••••••••••••••.••••••••••

-40oC to +S5°C

°C

Storage Temperature Range (TSTG)'

-40°C to +1SOoC

°C

Continuous Off State Voltage:
VoM ·····················•···•·•·········•····•···············•···········•· .

..••.••••.•..•.•.••.••••.••••.•••••••••••••••••••

NOTES:
1. Unit designed not to fail open below 450A.
2. One every 30 seconds maximum.

Equivalent Schematic Symbols

Gi±\
~

G~
7J.

G-+'
7J.

SURGECTORTM is a trademark of Harris Semiconductor
CAUTION: These devices are sensitive to electrostatic discharge. Users should follow proper I.C. Handling Procedures.
Copyright © Harris Corporation 1993

10-18

File Number

2762

Specifications SGT27S23
Electrical Specifications At Case Temperature (Tc = +25°C), Unless Otherwise Specified
LIMITS
PARAMETERS

MAX

UNITS

VOM = 270V
at Tc = +85°C

100

nA

50

I1A

VRM = lV
alTc = +85°C

1
10

mA

SYMBOL

Off-State Current

TEST CONDITIONS

10M

IRM
Holding Current

IH

On-Slale Voltage

VT

Gale Trigger Current

lOT

Main Terminal Capacitance

Co

TYP

MIN

rnA
rnA

230
IT= lOA

V OM = OV, Freq = 1MHz
VOM = 50V

2

V

175

mA
pF
pF

90
50

Performance Curves

--- .. _--mA

lOU

____ ... ___ ... _________

; s __

v
FIGURE 1. TYPICAL VOLT-AMPERE CHARACTERISTICS
C( 1.6

r---r---,r--.,---,---,--,----,

...oS

!.

Z

...z

IU
a: 1.4
a:
;:)

(J

a:

IU

CJ
CJ

1.2

IU

"'-

~

IU

!cCJ

a:
a:

;:)

(J

I'

1.0

::IE
a:
0

z

"-

0.8

0.6
-40

-20

r--,----,--,--,----,--,---,

1.8

;.6 "
1.4

CJ

0

~
«

2.0
C(

0

20

z

is

1.2

"

1.0

!:I
0

w
C
0

is
C
ox:

;ox:
...0

40

/
/

20

o

600

-

V

2.5

/

2

~

...
Z

w

ox:
ox:

:::> 1.5

/

/1

0

w
0

C

is

c
ox:

i...

EQUIV. SAT. ON
THRESHOLD -1.1V

0

0.5

/
800

TA=+250C
SINGLE PULSE

1000

1200

o

lkI

-'"1

o

/

I

/

IFWD

VFWD

2

3

FORWARD SCR VOLTAGE DROP (V)

FORWARD SCR VOLTAGE DROP (mV )

FIGURE 2. LOW CURRENT SCR FORWARD VOLTAGE DROP
CHARACTERISTIC

FIGURE 3. HIGH CURRENT SCR FORWARD VOLTAGE DROP
CHARACTERISTIC

INPUT
DRIVERS
OR
SIGNAL
SOURCES

•

IN 1-7

IN 9-15

V+

V-

SP720lNPUT
PROTECTION CIRCUIT
(1 OF 14 ON CHIP)

FIGURE 4. TYPICAL APPLICATION OF THE SP720 AS AN INPUT CLAMP FOR OVER-VOLTAGE, GREATER THAN 1 VBE ABOVE
V+ OR LESS THAN -1 Vae BELOW V-

11-8

SP720

Packaging

:?

B MIN
2
cnQI2t1
AREA~

INDEX

D

E16.3 (JEDECMS·001·AA)
16 LEAD DUAL.IN.LINE PLASTIC PACKAGE
INCHES

B1 M A X :

- 2-

-B-

~.

:
:

-I

FIGURE 2

Ir=E=;1

MILLIMETERS

SYMBOL

MIN

MAX

MIN

A

•

0.210

-

A1

0.015

MAX
5.33

NOTES
4

4

0.39

=J~GW~' m
.~~~ ~ lL~~-L~I-----+--+---+---t----II----t
Cl A1B®1
A2

0.115

0.195

2.93

4.95

B

0.014

0.022

0.356

0.558

Bl

0.045

0.070

1.15

l.n

9

I----+---+--+___+______+___

k&lO.010(O.25)®J

8B

FIGURE 1

NOTES:

e

0.008

0.015

0.840

0

0.745

0.005

E

0.300

0.325

7.62

8.25

6

El

0.240

0.280

6.10

7.11

5

18.93

21.33

0.100 BSe

2.54BSe

eA

0.3OOBSe

7.62 BSe

L

5

0.13

e

N

2. Dimensioning and tolerancing per ANSI Y14.5M-1982.

0.381

01

0.430

ee

1. Controlling Dimensions: Inch. In case of conflict between English
and Metric dimensions, the inch dimensions control.

0.204

0.115

0.160
16

10.92
2.93

4.06
16

6
7
4
8

3. Symbols are defined in the "MO Series Symbol list" in Section
2.2 of Publication No. 95.
4. Dimensions A, A 1 and L are measured with the package seated
in JEDEC seating plane gauge GS-3.
5. 0 and El dimensions do not include mold flash or protrusions.
Mold flash or protrusions shall not exceed 0.010 inch (025mm).
6. E and ~ are measured with the leads constrained to be per·
pendicular to plane e.
7. es and ee are measured at the lead tips with the leads unconstrained. ee must be zero or greater.
8. N is the maximum number of terminal positions.
9. Corner leads (1, N, N/2 and Nl2 + 1) may be configured as shown
in Figure 2.

z

OUI

-l-

I-(')::J
w(,)

5!!:

0:(,)

0..

11·9

SP720
Packaging (Continued)
M16.15 (JEDEC MS-012-AC)
16 LEAD NARROW BODY SMALL OUTLINE PLASTIC PACKAGE
INCHES

MILLIMETERS

SYMBOL

MIN

MAX

MIN

MAX

NOTES

A
Al

0.0532

0.0688

1.35

1.75

0.0040

0.0098

0.10

0.25

9

B

0.013

0.020

0.33

0.51

C

0.0075

0.0098

0.19

0.25

-

D

0.3859

0.3937

9.80

10.00

3

E

0.1497

0.1574

3.80

4.00

4

e

O.050BSC
0.2284

0.2440

5.80

6.20

h

0.0099

0.0196

0.25

0.50

5

L

0.016

0.050

0.40

1.27

6

SO

0°

a.
1. Refer to applicable symbol list.
2. Dimensioning and tolerancing per ANSI Y14.5M-19B2.
3. Dimension "D" does not include mold flash, protrusions or gate
burrs. Mold flash, protrusion and gate burrs shall not exceed
0.15mm (0.006 inch) per side.
4. Dimension "E" does not include interlead flash or protrusions. Interlead flash and protrusions shall not exceed 0.25mm (0.010
inch) per side.
5. The chamfer on the body is optional. If it is not present, a visual
index feature must be located within the crosshatched area.
6. "L" is the length of terminal for soldering to a substrate.
7. "N" is the number of terminal posilions.
8. Terminal numbers are shown for reference only.
9. The lead width "S", as measured O.36mm (0.014 inch) or greater
above the seating plane, shall not exceed a maximum value of
0.61mm (0.024 inch)
10. Controlling dimension: MILLIMETER. Converted inch dimensions are not necessarily exact.

11-10

-

-

H

N

NOTES:

1.27 SSC

16

16
0°

7
8°

-

SP721
Electronic Protection Array
for ESO and Overvoltage Protection

PRELIMINARY
August 1993

Features

Description

• ±2A Peak Current Capability

The SP721 is an array of SCRlDiode biploar structures for
ESD and over-voltage protection to sensitive input circuits.
The SP721 has 2 protection SCRlDiode device structures
per input. There are a total of 6 available inputs that can be
used to protect up to 6 external signal or bus lines. Over
voltage protection is from the IN (pins 1 - 3 & 5 - 7) to V+
orV-.

• Slngltrended Voltage Range. • • • • • • • . • . • . •. to +3SV
• Differential Voltage Range: ••.•••••••••••• to ±17.SV
• Designed to Provide Over·Voltage Protection
• Fast Switching. 6ns Risetime
• Low Input Leakages of 1nA at +2SoC Typical
• Low Input Capacitance of 3pF Typical
• An Array of 6 SCRlDiode Pairs
• Proven Interface for ESD
• Operating Temperature Range ...•.. ·400 Cto+10SoC

The SCR structures are designed for fast triggering at a
threshold of one +VSE diode threshold above V+ (Pin 8) or a
-VSE diode threshold below v- (Pin 4). From an IN input, a
clamp to V+ is activated if a transient pulse causes the input
to be increased to a voltage level greater than one VSE
above V+. A similiar clamp to V- is activated if a negative
pulse, one VSE less than V-, is applied to an IN input.
Further information is available in Application Note 9304.
AN9304 applies to both the SP720 and SP721

Applications
• Microprocessor/Logic Input Protection

Ordering Information
PART
NUMBER

• Data Bus Protection
• Analog Device Input Protection
• Voltage Clamp

TEMPERATURE
RANGE

PACKAGE

SP721AP

.4ooe to +1osoe

8 Lead Plastic DIP

SP721AB

-400 e to +1osoe

8 Lead Plastic SOIC

SP721ABT

-4Q°C to + 1osoc

8 Lead Plastic SOIC
Tape and Reel

Functional Block Diagram

Pinout
8 LEAD PLASTIC DIP
8 LEAD PLASTIC SOIC
TOP VIEW

z

Ocn

i=!::
0;:)

wo

be;

~o

Q.

CAUTION: These d9\lices are sensitive to electrostatic discharge. Users should follow proper I.C. Handling Procedures.
Copyright © Harris Corporation 1993

11-11

File Number

3590

Specifications SP721
Absolute Maximum Ratings
Continuous Supply Voltage, (V+) - (V-) ...••...•••..•.•••. +35V
Input Peak Current, liN •.•••.•.•..•..••.•.•••••.••.••.. ±2A
ESD Transient Ratings - See Note 2, Figure 1, Table 1
Maximum Package Power Dissipation:
8 Lead Plastic DIP Package, Up to +105°C: ......... 350mW
8 Lead Plastic SOIC Package, Up to +105°C: •••.•.•. 270mW

Thermal Resistance, 9JA :
8 Lead DIP Package ...••••••.•••••••••••••••..• 130oC/W
8 Lead SOIC Package ..•••.•..••••..•••••.•••••. 170oC/W
Storage Temperature Range .................. -65°C to +150°C
Junction Temperature ••••••.•.•••••.•••.••••••..•.• +150°C
Lead Temperature (Soldering lOs) •.••.••••••••••.••.• +265°C

CAUTION: StrsssBS above those listed in "Absolute Maximum Ratings" may cause permanent damage to the daviee. This is II strBSS only I8ting and opBl8tion
of the device at these or any other conditions above those indicated in the opel8tional sectIons of this specification Is not implied.

Electrical Specifications

TA = -40"C to +1 05°C, VIN = 0.5Vcc Unless Otherwise Specified
LIMITS

PARAMETERS

SYMBOL

Operating Voltage Range,
VSUPPLY = [(V+) - (V-)]

TEST CONDITIONS

TYP

MIN

4.5 to 30

VSUPPLY

Forward Voltage Drop
IN to VIN toV+

VFWOL
VFWOH

Input Leakage Current

liN

MAX

UNITS
V
V

Quiescent SupplyCurrent

2
2

liN = lA (Peak Pulse)
-20

laulEscENT

Equivalent SCR ON Threshold

Note 3

Equivalent SCR ON Resistance

VFWoIiFWo; Note 3

5

+20

nA

50

200

nA

1.1

V

1

0

Input Capacitance

CIN

3

pF

Input Sw~ching Speed

toN

6

nS

NOTES:
1. In automotive and battery operated systems, the power supply lines should be externally protected for load dump and reverse battery.
When the V+ and V- pins are connected to the same supply voltage source as the device or control line under protection, a current limiting
resistor should be connected in series between the external supply and the SP721 supply pins to limit reverse battery current to within
the rated maximum limits. Bypass capacitors of typically 0.01 ~F or larger from the V+ and V- pins to ground are recommended.
2. For ESO testing of the SP721 to MIL-STO 883, Method 3015.7, Human Body Model (HBM), the results are typically better than 6kV (Condition 1) (Figure 1, Table 1). Transient and ESD capability is highly dependent on the application. For conditions that are defined as an
in-circuit method of ESO testing where the V+ and V- pins have a retum path to ground, the ESO capability is typically greater than 15kV
from 100pF through 1.5kO (Condition 2) or 9kV from 200pF through 1.5kO (Condition 3). For ESO testing of the SP721 to EIAJ IC121
Machine Model (MM), the results are typically better than 1kV (Condition 4).
3. Refer to the Figure 3 graph for definitions of equivalent "SCR ON Threshold" and ·SCR ON Resistance". These characteristics are given
here for thumb-rule information to determine peak current and dissipation under EOS conditions.

TABLE 1. ESD TEST CONDITIONS

I
H.V.
SUPPLY
±Vo

Co

1

TEST

±Vo

Ro

Co

Condition 1

6kV

1.5kO

100pF

(HBM)

Condition 2

15kV

1.5kO

100pF

(Mod.
HBM)

Condition 3

9kV

1.5kO

200pF

(Mod.
HBM)

Condition 4

lkV

OkO

200pF

(MM)

IN
OUT
"',.?'

FIGURE 1. ELECTROSTATIC DISCHARGE TEST
MIL-STD-883D, METHOD 3015.7

11-12

SP721
100

80
;('

.§.

~

W
IE:
IE:

60

:::>
(,)

w

0

0

is 40
0

IE:

ifZ

j

20

o

600

-

2.5

/

TA-+2S0C
SINGLE PULSE

~

/

/

2

/

~

...
Z

W
IE:
IE:

:::> 1.5

/1

(,)

~

15

1/

0

I...

EQUIV. SAT. ON

0.5

/

800

TA-+260C
SINGLE PULSE

1000

1200

0

-"JJ

VFWD

1I
2
FORWARD SCR VOLTAGE DROP (V)

0

FORWARD SCR VOLTAGE DROP (my)

FIGURE 2. LOW CURRENT SCR FORWARD VOLTAGE DROP
CHARACTERISTIC

/

IFWD

:I

FIGURE 3. HIGH CURRENT SCR FORWARD VOLTAGE DROP
CHARACTERISTIC

+Vcc

INPUT
DRIVERS
OR
SIGNAL
SOURCES

T

IN1 -3

IN6-8

TO+VCC

Z

0(1)

i=!::
WO

0:::1

6!!:
a: 0
a.

V·

SP721 INPUT PROTECnON CIRCUIT (1 OF 14 ON CHIP)
(PINOUT CONAGURAnON SHOWN FOR 8 PIN PACKAGES)

FIGURE 4. TYPICAL APPLICATION OF THE SP720 AS AN INPUT CLAMP FOR OVER-VOLTAGE, GREATER THAN 1 VBe ABOVE
V+ OR LESS THAN -1 Vae BELOW V-

11-13

SP721

Packaging
B

MIN~. E8.3 (JEDEC Ms.-001·AB)

-2-

i

8 LEAD DUAL·IN-LiNE PLASTIC PACKAGE

B1 M A X '

INCHES

- 2FIGURE 2

MIN
_

AI

0.015

A2

0.115

0.195

2.93

4.95
0.558

FIGURE 1

NOTES:
1. Controlling Dimensions: Inch. In case of conflict between English
and Metric dimensions, the inch dimensions control.
3. Symbols are defined in the "MO Series Symbol Lisr in Section
2.2 of Publication No. 95.
4. Dimensions A, A 1 and L .are measured with the package seated
in JEDEC seating plane gauge GS-3.
5. D and E 1 dimensions do not include mold flash or protrusions.
Mold flash or protrusions shall not exceed 0.010 inch (0.25mm).
6. E and ~ are measured with the leads constrained to be perpendicular to plane C.
7. es and ec are measured at the lead lips with the leads unconstrained. ec must be zero or greater.
8. N is the maximum number of terminal positions.
9. Corner leads (I, N, N/2 andNl2 + 1) may be configured as shown
in Figure 2.

11-14

MIN
_

MAX

NOTES

5.33

4
4

0.39

B

0.014

0.022

0.356

Bl

0.045

0.070

1.15

1.77

C

0.008

0.015

0.204

0.381

0

0.348

0.430

8.84

01

0.005

10.92

0.13

E

0.300

0.325

7.62

8.25

6

El

0.240

0.280

6.10

7.11

5

e

0.100 BSC

2.54BSC

eA

0.3OOBSC

7.62 BSC

es

I

L

N

2. Dimensioning and tolerancing per ANSI YI4.5M-1982.

MAX
0.210

MILLIMETERS

SYMBOL
A

0.115

0.160
8

I 10.92

0.430
2.93

4.06
8

6
7
4

8

SP721

Packaging (Continued)
M8.15 (JEDEC MS-012-AA)
8 LEAD NARROW BODY SMALL OUTLINE PLASTIC PACKAGE
INCHES

fJB-

1 r-

D-----1

~Mfill

:--11--

MIN

A

h x 4$0

1ft
,

-T~~I

SYMBOL

~L
cJ

lei 0.10(0.0041\

1$l0.25(0.010)@lcIA@IB®1

MILLIMETERS

MAX

MIN

MAX

NOTES

0.0532

0.0688

1.35

1.75

A1

0.0040

0.0098

0.10

0.25

9

6

0.013

0.020

0.33

0.51

C

0.0075

0.0098

0.19

0.25

-

0

0.1890

0.1968

4.80

5.00

3

E

0.1497

0.1574

3.80

4.00

4

H

0.2284

0.2440

5.80

6.20

-

h

0.0099

0.0196

0.25

0.50

5

L

0.016

0.050

0.40

1.27

e

0.0506SC

N

a

1.27 6SC

0°

8°

0"

I

6
7

8

8

8°

-

NOTES:
1. Refer to applicable symbol list.
2. Dimensioning and tolerancing per ANSI Y14.5M-1982.
3. Dimension "0" does not include mold flash, protrusions or gate
burrs. Mold flash, protrusion and gate burrs shall not exceed
0.15mm (0.006 inch) per side.
4. Dimension "E" does not include interlead flash or protrusions. Interlead flash and protrusions shall not exceed 0.25mm (0.010
inch) per side.
5. The chamfer on the body is optional. If it is not present, a visual
index feature must be located within the crosshatched area.
6. "L" is the length of terminal for soldering to a substrate.
7. "N" is the number of terminal positions.
8. Terminal numbers are shown for reference only.
9. The lead width "6", as measured O.36mm (0.014 inch) or greater
above the seating plane, shall not exceed a maximum value of
0.61 mm (0.024 inch)
10. Controlling dimension: MILLIMETER. Converted inch dimensions are not necessarily exact.

Z

0(1)

i=!:::

()::::I

W()

b~

a:()

0.

11-15

Harris Semiconductor

----------~

=! "-

No. TB320

Harris Intelligent Power

August 1993

SP720/SP721 CMOS PROTECTION MODEL AND OTHER DATA
(A Supplement to Application Note, AN9304)
byW. Austin
Where the need to provide ESO protection for CMOS circuits
is the primary interest for the application of the SP720, interface characteristics of the device to be protected may lead to
some specific problems. Application related issues and precautions are discussed here to assist the circuit designer in
achieving maximum success in EOS/ESO protection.

Vcc

---------------... _----_
:,---------,, .......................
_.... _............. ,.........
--_ ...........;, _-,:
, ,

IN
V (I)
CS

CMOS logic has limited on-chip protection and may contain
circuit elements that add difficulty to the task of providing
external protection. Consider the case where the input structure of a CMOS device has on-Chip protection but only to the
extent that it will withstand Human Body Model minimum
requirement for ESO when tested under the Mil-Std 883,
Method 3015.7. This is normally ±2Kv where the charged
capacitor is 100pF and the series resistor to the device
under test is 15000. The circuit of Figure 1 shows the typical
network for an HC logic circuit where the input polysilicon
resistor, Rp is typically 1200.

: :

---+:

I

0,:1
: ~........... -.. - ....... -----........ ~----7-- . . .' :

INPUT

=Ics(t)·Rp + VFWD1 +Vec

(1)

Ves(t)
or

(1a)

les(t) = [Ves(t) - (VFWD' +VeclVRp

[for Neg. Vcs(t)]
or
Ies(t) = [Ves(t) - VFWD2VRp

While the circuit of Figure 1 is specifically that of the HC
logic family (one cell of the Hex Inverter, 74HCU04), many
CMOS devices have a similar or an equivalent internal protection circuit. When compared to the SCR structure of the
SP720, the on-chip diodes of the protection network in
Figure 1 have lower conduction thresholds.

·J-·:..:·~~~·
-

..·........T ..· ..,
CHIP
LOGIC

FIGURE 1. TYPICAL CMOS IC INPUT PROTECTION CIRCUIT

FORWARD SCR CELL
PROTECTION CIRCUIT

Vs(t)

ISP(t)

IN

REVERSE SCR CELL
PROTECTION CIRCUIT

FIGURE2. SP720SCRINTERFACETOACMOSINPUTWITHR1
ADDED TO ILLUSTRATE MORE EFFECTIVE ESD
PROTECTION FOR CMOS DEVICES

[for Pos. Ves(t)]

Similarly, when there is a negative transient, current initially
conducts at the negative threshold of diode O2, V FWD2 to
shunt negative current at the input, i.e.

I.· . .

II

ESD PROTECTION
NETWORK

When there is a surge or ESO voltage applied to the input
structure, the diodes shunt current to Vee or GNO to protect
the logic circuits on the chip. The on-Chip series resistors
limit peak currents. If there is a positive transient voltage,
Ves(t) , applied to the input of the CMOS device, the diode,
0, will conduct when the forward voltage threshold exceeds
the power supply voltage, Vee plus the forward diode voltage
drop of 0" VFWD " As the voltage at the input is further
increased, the CMOS current, les is shunted through Rp and
0 1 to Vee such that the transient input voltage is

(2a)

,,

Rp

les(l)l.

CMOS Input Protection

(2)

: :
"

SP720 to CMOS Interface
Figure 2 shows the SCR cell structures of one protection
pair in the SP720. In this example, the V+ of the SP720 is
connected to the Vee logiC supply and the V- is connected to
logic GNO. The IN terminal of the SP720 is connected to the
CMOS logic device input through a resistor RI. When a negative transient voltage is applied to the input circuit of Figure
2, the Reverse SCR Protection Circuit turns on when voltage
reaches the forward threshold of the PNP device and current
conducts through the SCR resistor to forward bias the PNP
transistor. The PNP device then supplies base current to forward bias and turn on the NPN device. Together, the PNP
and NPN transistors form an SCR which is latched on to

Copyright © Harris eorporation t993

11-16

Tech Brief 320
shunt transient current from IN to V-. The Forward SCR Protection Circuit has the same sequence for turn on when a
positive transient voltage is applied to the input and conducts to shunt transient current from IN to V+ (Veel.
The Voltage-Current characteristic of the SCR is similar to a
diode at low currents but changes to low saturated on resistance at high currents. As shown in the SP720 data sheet.
the forward SCR (latched on) voltage is -1V at 60mA which
is -O.2V higher than a typically junction diode. The fully saturated turn on approaches O.5A at 1.5V. When the SCR is
paralleled with the a CMOS device input having an on-chip
protection circuit equivalent to Figure 1. some of the current
necessary to latch the SCR is shunted into the CMOS input.
For some devices this may be sufficient for an ESD discharge to damage the CMOS input structure before the
SP720 is latched on.
The trade-off for achieving a safe level of ESD protection is
switching speed. The most effective method is the addition
of the series resistor. RI as shown in Figure 2. The series
input resistor. as shown. is a practical method to limit current
into the CMOS chip during the latch turn on of the SP720
SCR network. The value of RI is dependent on the safe level
of current that would be allowed to flow into the CMOS input
and the loss of switching speed that can be tolerated. The
level of transient current. les that is shunted into the CMOS
device is determined by the series resistor. RI and the voltage developed across the CMOS protection devices. Rp and
D1 or D2• plus some contribution from the path of diode. D3
for negative transients.

where current conduction in the SP720 may be positive or
negative. depending on the polarity of the transient. For the
circuit of Figure 2. Vset) is also the input voltage to the resistor. RI in series to the input of the CMOS device. When
latched on. the impedance of the SP720 is much less than
the input impedance of either RI or the CMOS input protection circuit. Therefore. the CMOS loop current can be determined by the voltage. Vset) and the known conditions from
equation (3).
For a negative transient input to the CMOS HCU04. the
loop equation is
(4)
Vs(t) = les(t)·(RI + Rp) + VFWD2
or
(4a)
les(t) [Vs(t) - VFWD2V(RI + Rp)

=

An equation solution for an input transient may be more
directly solved by empirical methods because of the non-linear characteristics. Given a transient voltage. Vs(t) at the
input. a value for RI can be determined for a safe level of
peak current into a CMOS device. The input Voltage-Current
characteristic of CMOS device should be known. As a first
order approximation. the CMOS V-I curve tracer input characteristics of the 74HCU04 are shown in Figure 4. As indicated in Figure 4. the voltage drop across Rp and RI in
series (Rp-120Q) will be significantly larger than the delta
changes in the forward voltage drop of the D1 or D2 diodes
over a wide range of current. As such. we can effectively
assume V FWD - O.75V for moderate levels of current.
~r-----"'-------------------------'

As shown in Figure 3. the voltage across the SP720 SCR
element is determined by its turn on threshold. VTH and the
saturated resistance. Rs when latched. The empirically
derived equation for the voltage drop across the SP720 voltage is
Vsp(t) = Isp(t)·Rs + VTH
or
Isp(t) = [Vsp(t) - VTHV(R s)
where VTH - ±1.1V and Rs - 1!l

(3)
(3a)
2.5

r--~----r----.----'r---~--..,

TA =2SoC
SINGLE PULSE
2

~
z

...

25L----~------------J
-3
-2
-1
0
1
2
3
4
5
6
7
8
HCU04 FORWARD AND REVERSE VOLTAGE DROP (mV)

w

II:
II:

1.5

:>
0

FIGURE 4. FORWARD AND REVERSE PROTECTION CIRCUIT
INPUT VOLTAGE-CURRENT CHARACTERISTIC
OF THE HCU04 SHOWN FOR Vce = SV,
(i.e. 0 1 THO - 5V + O.7V)

II:

0

III
C

II:

~

II:

0

II..

0.5

o~-~~~~~-~--~-~--~
o
2
3
FORWARD SCR VOLTAGE DROP (V)

FIGURE 3. FORWARD TURN ON CHARACTERISTIC OF AN
SP720 SCR CELL

Example Transient Solution
Based on the circuit of Figure 2. negative and positive ESD
discharge circuit models of the SP720 and HCU04 are shown
in Figure 5A and 58. The negative ESD voltage is taken as
the worse case condition because a pos~ive ESD voltage will
discharge to the Vee power supply and the positive offset

11-17

z

OU)

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0:::1

wo

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a:
Q.

Tech Brief 320
voltage will reduce the forward current. Using the negative
model,a peak current value for Isp can be determined by the
transient conditions of the applied voltage, V s(t) at the input.

·,...""'------,.

·t-----------".
:
:

ESO
PULSE

:
:

:
:
:

.. ·
·
:··: ..vo1 :..: IS~•••
·
L-i-~~--J
::

Ro:

Vs(l)

SP720
(NEG.
CELL)

and from equation (2) and (4a), a general solution for the
Vcs voltage is
Ves = [(Vs - VFW02)/(AI + Ap)]oAp + VFW02

(7)

For a Simpler approach, one can work backwards to arrive at
he correct solution. The reverse CMOS voltage vs current
curve of Figure 3 indicates that a peak voltage, Vcs of -3V
will produce a negative current of approximately -20mA
which is the rated absolute maximum limit. For a -15KV ESO
discharge and from Equation (6), the peak voltage, Vs is

:
:
:

.

=(VoIAo)oAs - 1.1 =(-15/1500)-1.1 =-11.1V

Vs

RS

~-- -----~

The peak current, Ics from equation (4a) is
Ics

FIGURE 5A. NEGATIVE ESD DISCHARGE MODEL

·
··
:·• 1

,---------'
"
•

. ··
.. IS~
:. ·
,

,-----------""
:
:

ESO
PULSE

:

: +vo
,

RD

vcc

:

CD'

t--t-----!

·
••
••
••

0:1:••

:

VsII)

••
:
:
:

= [(-11.1 -(-0.7»V(A I + 12(0)

,-----------"

••

:
:

(Pos.
CELL)
SP720

·••
.. . .---------..!.
••

.

'"' _________ t

HCU04
(FWD)

:
:

~

FIGURE 58. POSITIVE ESD DISCHARGE MODEL

Given MiI·Std ESD HBM test conditions (Co = 100pF and AD
= 15000). equation (3) with the resistors Ro and Rs in
series. we can calculate the peak current for a specified voltage. Vo on the capacitor, Co.
(5)

Isp(t)

=[Vo(t) - VTHV(Ro+ Rs) -

RI

Given an ESD discharge of -15KV. neglecting inductive
effects and distributed capacitance. the peak current at time
t 0 will be -1 OA. And. with the SP720 latched on as shown
in Equation (3). the 10A peak current will result in an ESO
pulse at the input of the SP720 of -11V. For the HCU04 to
withstand this surge of voltage, it is required that the dropping resistor. RI attenuate the peak voltage. Ves at the
HCU04 input to within acceptable ratings.

=

The negative reverse current path is through RI. Rp and O2;
where Rp and O2 are part of the HCU04.· For a negative. ESO
discharge voltage. Vo from capacitor Co. the equation for
the peak voltage. V cs at the input to the HCU04 is derived
as follows:
Substituting Equation (5) into Equation (3). we have

=397.50

The same result can be derived from equation (7) but is
more susceptible to rounding errors and the assumed voltage drop of VFW02 due to the (Ves - VFW02) difference that
appears in the equation.
The approximation solution given here is based on a ±20mA
current rating for the HCU04 device; although. input voltage
ratings are exceeded at this level of current. As such. the
solution is intended to apply only to short duration pulse conditions similar to the Mil-Std 883, Method 3015.7 specifications for ESO discharge conditions. For long periods of
sustained dissipation. the SP720 is limited by the rated
capability of its package.
-1.0

-10

-o.g

[Isp]t=o - VoI1500.

Vs - (VoIRo)oRs- 1.1

Given the Ics current of -20mA and solving for RI,

Vo(t)lRo

Here. Vo replaces Vs as the driving voltage; and assumes
that (1) Rs is much less than Ro; (2) Rs is much less than
(RI+Rp); and (3) VTH is much less than Vo. This mayor may
not be the general case but is true for the values indicated
here. As such.

(6)

=[(Vs - VFW02)/(AI + Ap)]

""

-o.B

-7

w
a:
a: -0.6
::.
(J
w
III -O.S
a:
w
>
w -G.4
a:
0

I:!

Co.
III

C

"' ....§.z
w

...~z -0.7

a:
a:

~

::.

-6

III

(J

w
a:
w

-4 >
w

a:

g

-0.3

.,'!

-G.2

::c
-2

-G.1

-1

(J

O~--~----&---~----~--~~

o

-0.4

-G.B

-1.2

-1.6

-2.0

REVERSE VOLTAGE IVs) TO THE SP7201HCU041NPUT (V)

FIGURE 6. MEASURED REVERSE CURRENT vs VOLTAGE
CHARACTERISTIC OF THE SP7201HCU04 FOR
THE FIGURE 2 CIRCUIT PROTECTION MODE

Figure 6 shows the distribution of currents for the circuit of
Figure 2 given a specific value of RI. Curves are shown for
both Is (HCU04 + SP720) and Isp (SP720) versus a negative
input voltage, Vs. The resistor. RI value of 100 is used here

11-18

Tech Brief 320
primarily to sense the current flow into the HCU04. (This
data was taken with the unused inputs to the HCU04 connected to ground and the unused inputs to the SP720 biased
to Vc d2 on a resistive divider.) The Figure 6 curves verify
the model condition of Figure 5A with the exception that
resistive heating at higher currents increases the resistance
in the latched on SCR. This curve explains the ESD protection of the Harris High Speed Logic "HC" family and, in particular, demonstrates the value of the Rp internal resistor as
protection for the HCU04 gate input. Added series resistance external to a signal input is always recommended for
maximum ESD protection.
Range of Capability
While the SP720 has substantially greater ESD self protection capability than small signal or logics circuits such as the
HCU04, it should be understood that it is not intended for
interface protection beyond the limits implied in the data
sheet or the application note. The Mil-Std 883, Method
3015.7 condition noted here defines a human body model of
100pF and 15000 where the capacitor is charged to a specified level and discharged through the series resistor into the
circuit being tested. The capability of the SP720 under this
condition has been noted as ±15KV. And, for a machine
model where no resistance is specified, a 200pF capacitor is
discharged into the input under test. For the machine model
the level of capability is ±1 KV; again demonstrating that the
series resistor used in the test or as part of the application
circuit has pronounced effect for improving the level of ESD
protection.
While a series resistor at the input to a signal device can
greatly extend the level of ESD protection, a circuit application, for speed or other restrictions, may not be tolerant to
added series resistance. However, even a few ohms of resistance can substantially improve ESD protection levels.
Where an ESD sensitive signal device to be protected has
no internal input series resistance and interfaces to a potentially damaging environment, added resistance between the
SP720 and the device is essential for added ESD protection.
Circuits often contain substrate or pocket diodes at the input
to GND or Vee. and will shunt very high peak currents during
an ESD discharge. For example, if the HCU04 of Figure 6 is
replaced with device having a protection diode to ground and
no series resistor, the anticipated increase in input current is
10 times.
Shunt capacitance is sometimes added to a signal input for
added ESD protection but, for practical values of capacitance, is much less effective in suppressing transients. For
most applications, added series resistance can substantially
improve ESD transient protection with less signal degradation.
A further concern for devices to be protected is forward or
reverse conduction thresholds within the power supply range
(not uncommon in analog circuits). Depending on the cost
considerations, the power supply V+ and V- levels for the

SP720 could be adjusted to match specific requirements.
This may not be practical unless the levels are also common
to an existing power supply. The solution of this problem
goes beyond added series resistance for improved protection. Each case must be treated with respect to the precise
V-I input characteristics of the device to be protected.
Interface and Power Supply Switching
Where separate system components with different power
supplies are used for the source signal output and the
receiving signal input, additional interface protection circuitry
maybe needed. The SP720 would normally have the same
power supply levels as the receiving (input) device it is
intended to protect. When the SP720 with its receiving interface circuit is powered off, a remote source signal may be
activated from a separate supply (Le., remote bus connected
systems). The user should be aware that the SP720 remains
active when powered down and may conduct current from
the IN input to the V+ (or V-) supply.
Within its own structure, any IN input of the SP720 will forward conduct to V+ when the input voltage increases to a
level greater than a Vbe threshold above the V+ supply. Similarly, the SP720 will reverse conduct to V- when the input
voltage decreases to a level less than a Vbe threshold below
the V- supply. Either condition will exist as the V+ or V- level
changes and will continue to exist as the V+ collapses to
ground (or V-) when the SP720 supply is switched off. If a
transient or power surge is provided from the source input to
the IN terminal of the SP720, after the V+ has been switched
off, forward current will be conducted to the V+Nee power
supply line. Without a power supply to clamp or limit the rising voltage, a power surge on the input line may damage
other signal devices common to the Vee power supply.
Bypassing the Vee line may not be adequate to protect for
large energy surges. The best choice for protection against
this type of damage is to add a zener diode clamp to the Vee
line. The zener voltage level should be greater than Vee but
within the absolute maximum ratings of all devices powered
from the Vee supply line.
Power Supply Off Protection, Rise/Fall Speed
To illustrate the active switching of the SP720 and the speed
of the SCR for both turn on and turn off, oscilloscope traces
were taken for the circuit conditions of Figure 7. A pulse
input signal is applied with NO supply voltage applied to the
SP720. Figure 7 shows the positive and negative pulse conditions to V+ and V-respectively. The trace scales for Figure
7 are 10ns/division horizontal and lV/division vertical. Input
and output pulses are shown on each trace with the smaller
pulse being the output. The smaller output trace is due to an
offset resulting from the voltage dropped across the SCR in
forward conduction. The OUT+ and OUT- pulses quickly
respond to the rising edge of the input pulse, following within
-2ns delay from the start of the IN pulse and tracking the
input signal. The output falls with approximately the same
delay.

11-19

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Tech Brief 320
POSITIVE/FORWARD CONDUCTION
HIGH SPEED ON/OFF PULSE (OUT+)

IN
(OUT+)

OUT+

FORWARD SCR CELL
PROTECTION CIRCUIT

±VGEN

(son)
IN
(13)

REVERSE SCR CELL
PROTECTION CIRCUIT

OUT-

GND

NEGATIVE/REVERSE CONDUCTION
HIGH SPEED ON/OFF PULSE (OUT-)
(OUT-)
IN

FIGURE 7. SP720 CIRCUIT WITH NO POWER SUPPLY INPUT PULSE TEST WITH son, (OV TO ±5V) INPUT. THE TRACE SCALES
FOR OUT+ AND OUT- ARE 1V/DIV VERTICAL AND 10nsIDIV HORIZONTAL

11-20

HIP 1090

I-IARRIS
SEMICONDUCTOR

Protected High Side Power Switch
with Transient Suppression

August 1993

Features

Description

• ±90V Transient Suppression

The HIP1090 is a Protected Power Interface Switch
designed to suppress potentially damaging overvoltage
transients with peak voltage source inputs ranging up to
±90V in amplitude. It is designed to be operated in a 'hardwired' pass-thru mode or as a high side power switch which
controls the current flow through a PNP pass transistor of
the IC. In either mode The HIP1090 has a low saturated
forward voltage drop. The protected load circuit is connected
to the output of the IC. As such, the HIP1090 operates as a
transient suppressor where the PNP drive transistor is
switched off when VIN is greater than the Overvoltage Shutdown range of 16V to 19V. Shutdown also occurs when VIN
is less than the forward turn-on threshold of approximately
2.5V, including the negative voltage range.

• 4V to 16V Operating Voltage
• 1A Current Load Capability
• Low Input-Output Voltage Drop With Controlled Saturation Detector for
- Fast Low Current Turn-OFF
- Reduced No-Load Idle Current
• Over-Voltage Shutdown Protection
• Short Circuit Current Limiting
• Over-Temperature Limiting Protected
• Thermal Limiting at TJ = +150 oC
• -40°C to +10SoC Operating Temperature Range

Applications

The merits of transient suppression depend on the required
integrity of the applications load elements. Instrument panel
signal warning lights for critical functions such as over
temperature or low fluid levels can be protected by the
HIP1090 against high level transient voltages and double
battery conditions that may potentially cause bulb burnouts.
The HIP1090 may be used to protect the power supplies of
small signal or logic circuits with voltages ranging from 4V to
16V, effectively blocking higher peak voltages.

• Electronic Circuit Breaker
• Transient Suppressor
• Overvoltage Monitor
• High Side Driver Switch for
- Relays
- Solenoids
- Heaters
- Motors
- Lamps

Ordering Information
PART
NUMBER
HIP1090AS

TEMPERATURE
RANGE

-40"C to +1OSoC

Pinout

PACKAGE AND
LEAD FORM
TO-220AB

The HIP1090 has internal current limiting protection in the
range of 1A to 2A for short circuit to ground conditions and
thermal shutdown protection when the junction temperature
is greater than 1500 C It is capable of driving resistive,
inductive or lamp loads (such as lamps No. 168 or 194) with
minimum risk of damage under harsh environmental stress
conditions. The HIP1090 is supplied in a 3 lead TO-220AB
package.

Functional Block Diagram
T0-220AB
TOP VIEW

,

,

~------------------------------------------------------------,

~~lfsINK

1 :
VIN
:
:
(Vcc OR

0

TAB --INTERNALLY
CONNECTED
TOPIN2

VBATT)

1 2 3

III
I

I

Rs

:

,,,
,,
,,
,
:,
,,__________________ ,.. ______________ .., __ ___ __

:

I

,
:

,,,
,,
,,,
:,
_ _______________ __ J,

3

~M

(TO LOAD)

11-21

WO

b!!:
a: 0

:

File Number

i=!::

0:::1

c..

VCON
(CONTROL OR GND)

CAUTION: These devices are sensitive to electrostatic discharge. Users should follow proper I.C. Handling Procedures.
Copyright © Harris Corporation 1993

z

OU)

3398.1

Specifications HIP1090
Absolute Maximum Ratings
Input (Supply) Voltage, VIN (Control Pin Reference)...•.•••• ±24V
Transient Max Voltage, VIN (l5ms) ....•.•.....•..•.•••• ± 90V
Load Current, lOUT' ...•......••.....•. Short Circuit Protected

Thermal Resistance, 8J c .•.....•........••••..••.•. 4°CIW
Junction Temperature .•.•..••.••..•..••..•......... +150°C
Ambient Temperature Range ••• . • . • • . • • . • • .. -40oC to +1 050 C
Storage Temperature Range •................• -40oC to + 150°C
Lead Temperature (Soldering During) ..........•••.••.. +265°C
1/16±1/32"(1.59 ± 0.79mm) from case for lOs maximum

CAUTION: Strssses above those listed in "Absolute Maximum Ratings' mey cause permanent damage to the device. This is a strsss only rating and operation
of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied.

Electrical Characteristics TA= _40°C to +105 't; VIN = 4V to 16V; VCON = GND or OV, Unless Otherwise Specified
LIMITS
CHARACTERISTICS

Inpul (Supply) Voltage Operating
Range

MIN

TYP

MAX

UNITS

(Note 1); Also, see Figure 4 for
Expanding VIN Range

4

-

16

V

Load = lKQ

-

2.5

-

V

16

-

19

V

100

I1A
I1A

TEST CONDITIONS

SYMBOL

VIN

Input Voltage Threshold for Forward
Turn-On to Load

VTHD

Input Voltage for Output Shutdown

VSHSD

(Note 2)

Output Shutdown Leakage

ILEAK1

VIN = 19V and 24V; Load = 1KQ

Output Cutoff Leakage

ILEAK2

VIN = 16V; Control Open; Load=l KQ

-

1

-

150

-

°C

Thermal Shutdown Temperature

TSD

Maximum Output Transient Pulse
Current

lour!Tran)

VIN = ±90V for 15ms, VOUT = 14V

-20

-

+20

rnA

Maximum Control Transient Pulse
Current

ICON(Tran)

VIN = ±90V for 15ms, VOUT = 14V

-50

-

+50

rnA

1

-

Short Circuit Current

Isc

Input-to-Output Voltage Drop

ICON

A
V

VIN = 4V, lOUT = 175mA

-

VIN = 9V, lOUT = 500mA

-

0.65

V

1.05

V

VIN = 16V, lOUT = lA

-

0.8

-

V

VIN = 16V, lOUT = 100mA

-

-

25

rnA

-

50

rnA

VIN = 16V, lOUT = 800mA

Control Current

2
0.25

VIN = 16V, lOUT = 800mA
VIN = 16V, lOUT = lA

-

50

-

rnA

-

-

20

115

-

-

20

115

Turn ON (Rise Time);
·Pass-Thru" mode

ioN

SWitch VIN OV(GND) to 5.5V; Measure
VOUT(to 90%); Load=lKn (Note 3)

Turn OFF (Fall Time);
"Pass-Thru· mode

IoFF

Switch VIN 5.5V to OV(GND); Measure
VOUT (to 90%); Load=l KQ (Note 3)

Turn ON (Rise Time);
High Pass Switch mode

ioN

See Figures 3 and 4 (Note 3)

-

15

Turn OFF (Fall Time);
High Pass Switch mode

IoFF

See Figures 3 and 4 (Note 3)

-

15

115

-

115

NOTES:
1. The Input Operating Voltage is not limited by the threshold of Shutdown. The VIN voltage may range to ±24V while the normal functional
switching range is typically +2.5V to +17.5V (reference to VCON )'
2. The Output Drive is switched-off when the Input voltage(Supply pin), referenced to the Control pin exceeds the threshold shutdown
VSHSD or the input voltage is less than the forward turn-on threshold (Including negative voltages within the transient peak ratings).
3. TON and TOFF times include Prop Delay and Rise/Fall time.

11-22

HIP 1090

Applications
The HIP1090 may be used as a "hard-wired pass-thru"
device to protect the load from source voltage transients or
may be used as an active high side power interface switch
with up to 1A of Load current capability. An ON state
condition of (VIN - 4V) S V CON S (VIN - 16V) is the normal
range required to activate the high pass switch, allowing the
supply source to conduct through the PNP to the load. When
the control terminal, VCON is open, the high pass switch is
open (no conduction). Figure 2 shows an HIP1090
application example with a switch in the VCON terminal. In
comparison to the hard wired circuit of Figure 1 where pin 2
is fixed at ground, pin 2 in the circuit of Figure 2 is switched
from open to ground to turn-ON the high pass switch. Used

in this mode, the HIP1090 is both an effective transient
suppressor and a high pass switch. The switch in the VCON
terminal may be active or passive and conducts typically less
than SOmA of current. The HIP1090 used in the controlled
switching mode retains all of the protected features of the
device. In either circuit the output capacitor may be
increased in size to hold charge longer during transient
interruptions at the input. The charge duration for larger
capacitors or for lamp loads is tolerated because of the
internal short circuit current limiting protection. 'Sustained
short circuits may cause the junction temperature to reach
the thermal shutdown temperature (150° C).

;------------------------------------------------------------..,
INPUT 1 : VIN

As

··:·
··
···:•
·

SWITCH~
veATT

DASH PANEL LOAD

VOUT! 3

TO OTHER
UGHTS
AND
INSTRUMENTS

•

~ ----------------------------------------2

-----------------.!

VCON

(CONTROL OR GND)
FIGURE 1. TYPICAL APPLICATION OF THE HIP1 090 AS A TRANSIENT SUPPRESSOR IN A "PASS-THRU· MODE

r----.. . ·. . . . . ---.. . -.. ---.. . . --.. . . . -------.. ·. . . ---.. -------.. . . ------,

·

INPUT 1

VIN
Rs
VOUT: 3
VBATT--~-+----------~~~~------------~ r----~--~r_;-~--~~--~--~

:
•

r---.., ..."--..a..., ,...._...1..., ..-"'-....., .....- . . . .., ·:•

..
~

·•:

.........,._......_..,............._ _.......-..-...........- r -.... :•

______ .. _________ .... ____ .. __ ... _____________ ...

2

=

VCON

(CONTROL)

NOTE:
V LOAD

.•

__________________ J

V BATT - V SAT

VSAT TYP < O.BV at 1A

OFF~ ON

SWITCH~

FIGURE 2. TYPICAL APPLICATIONS OF THE HIP1090 AS A TRANSIENT SUPPRESSOR IN A HIGH PASS SWITCH MODE

11-23

z

Ow
i=!::

(,);:)
w(,)

b~

0::(,)

Il.

HIP 1090
Figure 3 shows the pulsed output switching characteristics of
the HIP1090 as a high side driver. A small delay step is
noted on the rising edge due to the hold-off of a VcESAT
detector circuit. The VCESAT circuit senses the saturation
level of the PNP pass transistor and controls the drive as a
ratio of load current. As the load current is reduced, the drive
current to the output transistor is reduced. Under low current
operation, the saturation level is controlled and the turn-OFF
switching time is much faster. The control switching element
is shown as a 2N5320 NPN transistor but may be any open
collector or MOS gale. A pull-up resistor of 2k!l is used for a
slight improvement in the turnoff fall time but is not an
essential requirement. The V CON terminal may be controlled
with a mechanical switch or may be controlled from any
driver output that can sink the worst case condition of pin 2
current, ICON when the output load current is increased to 1A
(typically 50mA).

The circuit of Figure 4 shows how the HIP1090 transient
suppression voltage shutdown threshold may be increased
by using a zener diode from the VCON terminal to the collector terminal of the transistor switch. The preferred method is
to use a zener diode for a fixed level shift. While a resistor in
place of the zener diode having the same voltage drop will
work well, the parametric variation of the ICON current will
cause variations of the Over-Voltage Shutdown Threshold.
In this Circuit, a 10V zener provides a typical overvoltage
threshold shift to -27V. The threshold for overvoltage shutdown is referenced to the (VIN - VCON) voltage difference.
+24V

2KO
OPTIONAL

ON

+16V

HIP1090

(SUPPLY INPUT)

L-_ _ _ _

~

VCON

ON

n

OFFJ

OR EQUIVALENT

L-

,

:
,:

VOUT

:
,:

l

o-----I
__
::
5

I

: _________________ 1-: __________ ,I_
L

:TOFF:

:......E--1:_0_N---->~!

:

15J1S 31:

ON·

,

OFF']

I

I

I 'I(

•

15...
VB

OR EQUIVALENT

L-

Also, it is important to note that high peak current values
may be reached when driving nonlinear and inductive loads.
The peak output current of the HIP1090 is self limiting in the
1A to 2A range to protect against short circuit conditions.
Sustained high peak current may increase the junction temperature to 150°C and cause thermal shutdown. When this
happens, the output current will fall off briefly before recovering, unless the over-temperature condition is sustained.
Internally, both input and output overvoltage conditions are
sensed to protect the circuit, making the high levels of transient voltage ratings possible. Sustained voltage ratings of
±24V DC with transient ratings to ±90V allow a wide variety
of applications in high stress environments.

15 --~------------------'-,
10

0-

2N5320

FIGURE 4. A TYPICAL APPLICATION CIRCUIT THAT USES A
ZENER TO THE V eoN TRANSISTOR SWITCH TO
RAISE
THE
OVERVOLTAGE
SHUTDOWN
THRESHOLD

2N5320

VB 0-

10V

1kn

_

(CONTROL PIN)

1kn

n

OFFJ

24D

2KO
OPTIONAL

HIP1090

(SUPPLY INPUT)

:

:

i

FIGURE 3. TYPICAL ON-OFF SWITCHING CHARACTERISTIC
OF THE HIP1 090 USING AN NPN TRANSISTOR TO
SWITCH THE VCON INPUT TERMINAL

Except for the VcESAT detector circuit, the HIP1090 is a
higher current version of the CA3273 high side driver, which
turns-on without the delayed step on the leading edge of the
output pulse; switching with a typical TON time of -O.5I-ls.
The CA3273 has a higher transient suppression threshold.

11-24

HIP 1090

Typical Performance Curves
60

<"
g
~

50

z
~
z
w
a:
a:

~

40

...

30

0

20

::>

...a:z

RLOAD .16Q
VCOH-GND

.!;

....
0

f - - r-

/

/

g<"

,

TA=+250C

30

I

r--

z 25

..?

VCON=GND

~ 20

...z~
w

15

a:
a:

::>
0

/'

....

,

10

0

I!:

10

t5

0

0

0

10

15

20

5

o

o

VIN SUPPLY VOLTAGE (V)

I

g

1000

r--

w

~

;..0

;j;

~

•~

~

II

RLOAD=1&l

/

400

o

-'"
o

20

I

600

200

15

TA=+25oC

~

]

10

FIGURE 6. CONTROL (QUIESCENT) CURRENT CHARACTER·
ISTIC WITH NO LOAD

VCON. GND

800

5

VIN SUPPLY VOLTAGE (V)

FIGURE 5. CONTROL (QUIESCENT) CURRENT CHARACTER·
ISTIC WITH LOAD

:;-

VOUTOPEN

z

tI'

",.V

5

I

TA=+250C

J

/'

0.5

1.0

1.5

LOAD CURRENT, lOUT (A)

FIGURE 7. SATURATION (VIN • VOUT) CHARACTERISTIC

Z

011)

i=!:::

():::I

W()

15g;
a:()
Q.

11·25

HIP 1090
Packaging

1f-I~ J l3~~
r--.
"p~r-E4

ttl'

~

0

r]o,

I ,
t , , Ii-1 • 1-L,

L

.

G:L'
.....

4SO

TO-220AB
3 LEAD JEDEC TO-220AB PLASTIC PACKAGE
INCHES
MIN

MAX

MIN

MAX

NOTES

A

0.170

0.180

4.32

4.57

A,

0.048

0.052

1.22

1.32

-

TERM. 4

3

bl

, ,

b

c-

1 2 3
.... e f el l-

MILLIMETERS

SYMBOL

....

b

0.030

0.034

o.n

0.86

3,4

b,

0.045

0.055

1.15

1.39

2,3
2,3,4

c

0.014

0.019

0.36

0.48

0

0.590

0.610

14.99

15.49

0,

-

0.160

-

4.06

E

0.395

0.410

10.04

10.41

E,

-

0.030

-

0.76

e

-IJlf-

e,

O.looTYP
0.2OO9SC

-

-

2.54 TYP

5

5.089SC

5

H,

0.235

0.255

5.97

6.47

-

J1

0.100

0.110

2.54

2.79

6

Lead No.1

- Gate

Lead No.2

- Collector

L

0.530

0.550

13.47

13.97

-

Lead No.3

- Emitter

L,

0.130

0.150

3.31

3.81

2

0P

0.149

0.153

3.79

3.88

Q

0.102

0.112

·2.60

2.84

Mounting Flange - Collector

-

-

NOTES:
1. These dimensions are wnhin allowable dimensions of Rev. J of
JEDEC m-220AB outline dated 3-24-87.
2. Lead dimension and finish uncontrOlled in L,.
3. Lead dimension (without SOlder).
4. Add typically 0.002 inches (O.05mm) for solder coating.
5. Position of lead to be measured 0.250 inches (6.35mm) from bottom of dimension D.
6. Position of lead to be measured 0.1 00 inches (2.54mm) from bottom of dimension D.
7. Controlling dimension: Inch.
8. Revision 1 dated 1-93.

11-26

TV

12
APPLICATION NOTES

PAGE
APPLICATION NOTES

AN8820.2

Recommendations For Soldering Terminal Leads to MOV Varistor Discs. . . . . . . . . . . . . . . . . . . .

12-3

AN910B.1

Harris Multilayer Surface Mount Surge Suppressors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

12-5

AN9211

Soldering Recommendations for Surface Mount Metal Oxide Varistors
and Multilayer Transient Voltage Suppressors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

12-15

AN9304.1

ESD and Transient Protection Using the SP720 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

12-22

AN9306

The New "cuill Series of Metal Oxide Varistors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

12-27

AN9307

The Connector Pin Varistor for Transient Voltage Protection in Connectors. . . . . . . . . . . . . . . . ..

12-32

AN9308

Voltage Transients and Their Suppression. . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

12-39

AN931 0

Surge Suppression Technologies Advantages and Disadvantages
(MOVs. SADs. Gas Tubes. Fitters & Transformers) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. ..

12-44

AN9311.1

The ABCs of MOVs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. ..

12-50

AN9312.1

Suppression of Transients in an Automotive Environment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

12-53

12-1

Harris Semiconductor

-

No. AN8820.2

Harris Varistor Technology

April1993

RECOMMENDATIONS FOR SOLDERING TERMINAL LEADS TO
MOV VARISTOR DISCS
Introduction

Fluxes

The CA series of MOV varistor discs with silver electrodes
are specifically designed for custom assembly and packaging. To take advantage of the excellent performance and
reliability of Harris varistor technology, it is important that the
correct materials and processes be used to solder on the
terminal leads.

Fluxes are used for chemical cleaning of disc and terminal
surfaces. There are three basic types:
R - These unactivated fluxes are less effective than the
others in reducing oxides of copper, nickel, or
palladium/silver metallizations, but are the ones recommended for MOV varistors. All other fluxes
increase leakage, reduce long term reliability, and
can promote leaching of the silver electrode. Noncharring, non-activated R type fluxes such as Alpha
100 or its equivalent are best.

Solder Fixtures
Where varistor discs are custom assembled and packaged,
fixturing is normally employed to maintain disc and terminal
alignment during solder reflow. Soldering fixtures should be
of lightweight design to reduce their thermal mass and, hence,
the time necessary to bring them to reflow temperature.

RMA - These are mildly activated fluxes, and the most commonly used in the mounting of electronic components. They may be used with varistors, but are not
recommended.

Disc and terminal lead should be pressed together lightly
during the whole soldering process to help expel flux
residues and excess solder from the interface. Trapped flux
residue can result in bubbling of the solder, which leaves
voids between silver electrode and terminal. Excess solder
will enhance the tendency of the silver electrode to leach.

RA - These fully activated fluxes are corrosive, difficult to
remove, and can lead to varistor failure. They must
not be used to flux varistor discs.

Solders and Solder Temperature

Soldering Ovens
Box, convection, and conveyor belt ovens are suitable for
reflow solder processes using fixtures.
Box ovens should have forced air circulation with sufficient
ventilation to remove flux vapors. It is important that every
fixture position in the oven be subjected to the same heating
conditions. Therefore, fixture positions should be limited to
locations within the oven where uniform air flow and temperature can be maintained.
Convection ovens employ carefully designed exit baffles to
facilitate close control of the soldering environment. Air is the
best environment for soldering varistors. An inert gas (nitrogen) or reducing atmosphere is sometimes employed to
reduce oxidation in these ovens, but neither of these is recommended for the processing of un passivated varistors.
A very repeatable temperature profile can be achieved with a
conveyor belt oven. The profile is determined by the temperature of the heated zone(s) and the speed of the belt. A fixed
loading pattern also helps in achieving uniform results.

Solders in the form of pastes or preforms can be used with
varistors. Preforms are solder shapes premanufactured to
specific sizes. Upon melting, they provide highly reproducible volumes of solder for joining. Preforms can be prefluxed,
eliminating the need for any additional fluxing.
Heat should not be applied to a varistor too quickly, as the
flux will not have sufficient time to activate and clean the joining surfaces. The result will be poor solderability. On the
other hand, no varistor should be held longer than necessary at an elevated temperature. If heat is applied too slowly
or maintained above reflow temperature for too long, leaching of the silver electrode into the solder will occur, reducing
the disc to terminal bond strength. To avoid leaching, only
solders with at least 2% silver content (e.g., 62Sn/36Pb/2Ag
or equivalent) should be used; see Table 1.
It is equally important to observe processing time and
temperature limits. Failure to do so can result in excessive
leakage and alterations of the varistor's VI characteristic.

Copyright © Harris Corporation 1993

12-3

Application Note 8820
Cleaning and Cleaning Fluids
Cleaning is an important step in the soldering process. It
prevents electrical faults such as the high current leakage
caused by ionic contamination, absorbed organic material,
dirt films, and resins.
A wide variety of cleaning processes can be applied to varistors, including water based, solvent based or a mixture of
both, tailored to specific applications. Harris recommends
1.1.1 trichloroethane for the removal of flux residues after
soldering.
Defluxing in a solvent bath with ultrasonic agitation, followed
by a solvent vapor wash, is a very effective cleaning process.
After cleaning, the low bOiling point solvent completely evaporates from the disc, and will not harm solder joints.

12-4

TABLE 1. SILVER BEARING SOLDERS (ALPHA METALS)

ALLOY

MELTING
TEMPERATURE

62Snl36Pb12AG

179"C

96.5SnI3.5Ag

221°C

96Snl5 Ag

221°C - 245°C

10Snl88Pbl2Ag

26SOC - 302°C

5Snl92.SPbl2.5Ag

280°C

97.SPbl2.SAg

30SoC

Harris Semiconductor

-

No. AN9108.1

-

Harris Suppression Technology

August 1993

HARRIS MULTILAYER SURFACE MOUNT
SURGE SUPPRESSORS
Author: Martin Corbett

Introduction
Sensitivity of Components
Modern electronic circuits are much more vulnerable to damage from transient overstresses than earlier circuits, which
made use of relays and vacuum tubes. The progress in the
development of faster and denser integrated circuits has
been accompanied by an increase in system vulnerability. As
the use of such systems has increased so to has the need
for their protection. Figure 1 shows damage susceptibility of
some commonly used components, including discrete semiconductors and integrated circuits 1,2.
As many semiconductor devices can be damaged by potential differences that exceed 10 volts, the survivability of modern electronics is limited when exposed' to transient
overvoltages. The advent of smaller faster technologies,
such as high speed logic and MOSFETs, has led to an
increased vulnerability of electronic circuits to damage from
overstresses. The voltage, current, or power seen by a
device must be below the failure threshold of the device. The
value of this threshold is a function of the magnitude and

duration of a transient overvoltage occurrence. The magnitude of the transient is determined by the nature of the
source, the characteristic impedance of the circuit and the
resistance and inductance between the source of the transient and the device.
Integrated circuits are sensitive components, and their
threshold for damage is difficult to increase. Therefore, transient protection of these sensitive circuits is highly desirable
to assure system survival.
Digital integrated circuits produced with TTL technology are
fairly rugged devices and are relatively insensitive to high
speed transients. However, ICs designed with new technologies, that have thinner gate oxides and higher cell denSities,
are more susceptible to voltage transients.
When looking at the gate oxide cross section of devices
using existing and new technologies, it is realized that the
susceptibility to transients is continuously increasing due to
the potential of damage with ·punch-through". In order to
EMPAND
UGHTNING

EMI AND ESD
• DIODES
WAVE MIXER
GP SIGNAL
RECTIFIERS
REFERENCE
ZENER
• TRANSISTORS
LOW POWER
HIGH POWER
• DIGITAL IC
TTL
DTL
RTL
ECl
MOS
UNEARIC
• BASIC COMPONENTS
SCRS
JFETS
CAPACITORS
RESISTORS

I
0.1

I
10

I

102
WATTS

EMI-ELECTROMAGNETICINTERFERENCE
ESD - ELECTROSTATIC DISCHARGE
EMP - ELECTROMAGNETIC PULSE

FIGURE 1. RELATIVE DAMAGE SUSCEPTIBILITY OF ELECTRONIC COMPONENTS (FOR 11lS PULSE)
Copyright © Harris Corporation 1993

12-5

Application Note 9108
work with these devices successfully, the sensitivity of such
devices must be fully understood, and adequate precautions
taken to ensure reliable operation, as well as survival in
harsh environments. Table 1 shows a comparison of the feature size, supply voltages, and typical gate count of various
Ie technologies.
TABLE 1. CURRENT INTEGRATED CIRCUIT TECHNOLOGY

BIPOLAR

MOS

BiMOS

POWER
BiMOS

Feature Size
(11M)

5.0

1.0

1.5

3.0

Typical Gate
Count

500

6

16

80

Typical Supply
Voltage (Volts)

+60

+6

+16

+80

PROPERTIES

may also set off oscillations, making the problem even
worse.
While a direct hit from lightning is not of real concern for a
printed circuit board user, what may be of concern is the
level of the transient which is "let through" by the primary
suppressor. This "follow on currenf' may be up to 50 amps
and it will last for a number of microseconds. If this current is
above the failure threshold of a device in the Circuit, it will be
destroyed.
Hopefully, the threat of transients generated from nuclear
electromagnetic pulses (NEMP) will not be a real concern.
However specific requirements do exist to ensure that systems are protected from the fast rise pulses of NEMP. These
transients have a rise time of approximately 5 nanoseconds
and are of a magnitude similar to that encountered from
lightning.

When designing to protect systems, it is desirable to ensure
that worst cases stresses are below the failure threshold of
the circuit. In the situation where information on the failure
threshold is unknown, it is permissible to use a factor of 2
above the device/system steady state ratings and specify a
brief duration at this over stress level (usually a few microseconds). Such an approach has been endorsed by the U.S.
Department of Defense Military Handbook 419 3 .
When sensitive devices are specified in a circuit, transient
protection must not be treated as an afterthought. If no transient suppressor is used, the weakest device absorbs most
of the transient energy, with a high probability of a failure. If
the failed device is replaced by one having higher breakdown ratings, the next weakest device will take over the unintended roll of transient suppressor, and system failure could
still result. Simply replacing failed devices with higher capability parts does not guarantee system reliability.
The Transient Threat
Transients exist in every AC or DC system, or any wire connecting two pieces of equipment or components. The
sources of the transient can be lightning, nuclear electromagnetic pulse, high energy switching and high voltage
sparkover, or electrostatic discharge. These transients may
be found wherever the energy stored in inductances, capacitors, or mechanical devices, such as motors and generators,
is returned to a circuit. Stray capacitance and inductance

The two most likely types of transients from which a circuit
must be protected are electrostatic discharge (ESD), and the
switching of reactive loads. ESD will result when two conducting materials are brought close to one another and a
voltage discharge occurs. The resulting voltage discharge
can be as high as 25KV and will last up to 50 nanoseconds.
One of the most common methods of "zapping" circuits is
walking across a carpeted floor, building up an electrical
charge, and touching a device without being properly
grounded. Transients can also be generated when an inductive load is disconnected and the existing energy is discharged back into the circuit. The arc generated from the
opening of mechanical relay switches is another common
source of switching transients.
Whatever the cause of the transient, natural or man-made,
the damage potential is real and cannot be casually dismissed if reliable operation of equipment is to be expected.
To properly select a transient suppressor, the frequency of
occurrence of transients, the open-circuit voltage, the short
circuit-current, and the source impedance of the circuit must
be known.
To date, designers have used resistors, capacitors, inductors, metal-oxide varistors, zener diodes, silicon carbide
varistors, spark gaps, carbon blocks, or combinations of
these to suppress transients and protect sensitive components. The new Harris series of Multilayer (ML) surge suppressors represents a unique and effective solution for
transient suppression.

12-6

Application Note 9108
Multilayer Surge Suppressor
Description
The Harris multilayer (ML) series of transient voltage surge
suppressors represents a recent breakthrough in the area of
semiconducting ceramic processing. The ML suppressor is a
compact, surface mountable chip that is voltage dependent,
non-linear, and bi-directional. It has an electrical behavior
similar to that of a back-to-back diode, i.e. it is inherently fully
symmetrical, offering protection in both forward and reverse
directions. The sharp, symmetrical breakdown characteristics of the device provides excellent protection from damaging voltage transients (Figure 2). When exposed to high
voltage transients, the ML impedance changes many orders
of magnitude from a near open circuit to a highly conductive
state.

---:_--+--~-v

Energy handling capability can be significantly increased
with a larger overall package outline. The energy handling
capability doubles from 0.6 Joules (10/1000ms waveform)
for a 0.120 inch by 0.06 inch device to 1.2 Joules for a 0.120
inch by 0.100 inch device.
The crystalline structure of the ML transient voltage suppressor (TVS) consists of a matrix of fine, conductive grains
separated by uniform grain boundaries, forming many P-N
junctions (Figure 4). These boundaries are responsible for
blocking conduction at low voltages, and are the source of
the nonlinear electrical conduction at higher voltages.
Conduction of the transient energy takes place between
these P-N junctions. The uniform crystalline grains act as
heat sinks for the energy absorbed by the device in a
transient condition, and ensures an even distribution of the
transient energy (heat) throughout the device. This even
distribution results in enhanced transient energy capability
and long term reliability.

ARED CERAMIC
DIELECTRIC

_ _~GII!Idl1I1!!!II!BlmIQ

FIGURE 2. SHARP SYMMETRICAL BREAKDOWN OF MULTILAYER SUPPRESSOR

Construction
METAL
ELECTRODES

The ML is constructed by forming a combination of alternating electrode plates and semiconducting ceramic layers into
a block. Each alternate layer of electrode is connected to
opposite end terminations (Figure 3). The interdigitated
block formation greatly enhances the available cross-sectional area for active conduction of transients. This paralleled
arrangement of the inner electrode layers represents significantly more active surface area than the small outline of the
package may suggest. This increased active surface area
results in proportionally higher peak energy capability.

GRAINS

FIGURE 4. MULTILAYER TRANSIENT VOLTAGE SUPPRESSOR

SEMICONDUCTING
CERAMIC

Package Outline
INNER
ELECTRODES

END
TERMINATION

FIGURE 3. MULTILAYER INNER ELECTRODES & SEMICONDUCTING CERAMIC (CROSS-SECTION)

Another advantage of this type of construction is that the
breakdown voltage of the device is dependent on the dielectric thickness between the electrode layers and not the overall thickness of the device. Increasing or decreasing the
dielectric thickness will change the breakdown voltage of the
device.

The ML surge suppressor is a surface mountable device that
is much smaller in size than the components it is designed to
protect. The present size offerings are a "1210" form factor
(0.120 inches x 0.100 inches) and a "1206" form factor
(0.120 inches x 0.060 inches). Since the device is inherently
bi-directional, symmetrical orientation for placement on a
printed circuit board is not a concern. Its robust construction
makes it ideally suitable to endure the thermal stresses
encountered in the soldering, assembling and manufacturing
steps involved in surface mount applications. As the device
is inherently passivated by the fired ceramic material, it will
not support combustion and is thus immune to any risk of
flammability which may be present in the plastic or epoxy
molded parts used in industry standard packages.

12-7

Application Note 9108
Characteristics
Speed of Response

Temperature Dependence

The clamping action of the ML suppressor depends on a
conduction mechanism similar to that of other semiconductor devices. The response time of the zinc oxide material
itself has been shown to be less than 500 picoseconds3• 4. 5.
The apparent slow response time often associated with zinc
oxide is due to parasitic inductance in the package and
leads. Thus. the single most critical element affecting the
response time of any suppressor is its lead length and.
hence. the inductance in the leads. As the ML suppressor is
a true surface mount device. with no leads or external packaging. it has virtually zero inductance. In actual applications.
the estimation of voltage overshoot is of more practical
relevance than that of speed of response. As a multilayer
suppressor has essentially zero inductance it has little or no
voltage overshoot. The actual response time of a ML surge
suppressor is 1 to 5 nanosecond. This response time is
more than sufficient for the transients which are likely to be
encountered by a component on a printed circuit board.

In the off state. the V-I characteristics of the ML suppressor
approaches a linear (ohmic) relationship and shows a
temperature dependent affect (Figure 6). The suppressor is
in a high resistance mode (approaching 109 ohms) and
appears as a near open circuit. This is equivalent to the leakage region in a traditional zener diode. Leakage currents at
maximum rated voltage are in the microamp range. When
clamping transients at higher currents (at and above the
milliamp range). the ML suppressor approaches a near short
circuit. Here the temperature variation in the characteristics
of the ML becomes minimal throughout the full peak current
and energy range (Figure 7). The clamping voltage of a
multilayer transient voltage suppressor is the same at +25 0 C
and at +125°C.

Clamping Voltage
The clamping voltage of a suppressor is the peak voltage
appearing across the device when measured under the conditions of a specified pulse current and specified waveform.
The industry recommended waveform for clamping voltage
is the 8/20 microsecond pulse which has been endorsed by
UL. IEEE and ANSI. The clamping voltage of the ML should
be the level at which a transient must be suppressed to
ensure that system or component failure does no occur.
Shunt-type suppressors like the ML are used in parallel to
the systems they protect. The effectiveness of shunt
suppressors can be increased by understanding the
important influence that source and line impedance play in a
system. such as is shown in Figure 5.

r

-i"""'
1~~~~--~--~--~--~--~--~~

-60

-50

-40

-30

-20

-10

0

10

20

30

TEMPERATURE ("C)

FIGURE 6. TEMPERATURE DEPENDENCE AT LOWER
VOLTAGE

60,----r----,-----,----,---------------,
V26MLA1206

~ 50 ~=::j:==+==t:=::t==:t==t:"'-I
w

~ 40r----t----~----+---_i-----r----i---~

!:i

~

ZSOURCE

~VSOURCE

30

r-=-F=='*'''"''=;f;;;''"''''''''..........

..;V;.;1,;::4M::;LA:;;;.:1.;206::;...

I I
:3~ 20 t - - t - - t - - t - - - t - - V3.5MLA1206

SYSTEM
TO BE
PROTECTED

U 10r----t----~----+---_i-----r----i---~
O~--~----~----~--~-----L----~--~
20
60
80
100
120
140
160

40

TEMPERATURE (OC)

FIGURE 5. VOLTAGE DIVISION BETWEEN SOURCE. LINE
AND SUPPRESSOR IMPEDANCE

To obtain the lowest clamping voltage (Vel possible. it is
desirable to use the lowest suppressor impedance
(ZSUPPRESSOR) and the highest line impedance (ZUNE)' The
suppressor impedance is an inherent feature of the device.
but the line impedance can become an important factor. by
selecting location of the suppressor. or by adding resistances or inductances in series.
V

_

VSUPPRESSOR x VSOURCE

C - ZSUPPRESSOR + ZLiNE +ZSOURCE

FIGURE 7. CLAMPtNG VOLTAGE VARIATION OVER
TEMPERATURE

Peak Current Capability
The peak current handling capability. and hence its ability to
dissipate transient energy. is one of the ML suppressor's
best features. This is achieved by the interdigitated construction of the ML. which ensures that a large volume of
suppressor material is available to absorb the transient
energy. This structure ensures that the peak temperatures
generated by the transient is kept low, because all of the
package is available to act as an effective. uniform heat sink
and absorb all the energy.

12-8

Application Note 9108
(Figure 8). Because of the low peak temperatures, the ML
will experience very low thermal stress, both during heating
and cooling.
METAL
ELECTRODES
QL7L7L7L7L7C

l LJLJI

II II II

:bdbdbdbdbdbdL Jd;

DEPLETION
REGION

fRRP gg 92J
r88pOD9aJ
II II II

The present offering of multilayer suppressor sizes is 1206
(0.120 x 0.060 inches) and 1210 (0.120 x 0.100 inches).

looooooEfJ

DEPLETION
REGION

JLJLJ~LJI

Comparison to Other Transient
Suppressors

" - - GRAINS
FIGURE 8. INTERDIGITATED CONSTRUCTION
Repetitive pulsing on the ML suppressors (Figure 9) show
negligible shift in the nominal voltage at one milliamp (less
than 3%). There was also a minimal change in the leakage
current of these devices. The Harris ML suppressor can also
operate up to +125 0 C without any need for derating.

100

V26MLA1206 150 AMPS (8120ms) 10,000 PULSES
NOMINAL VOLTAGE AT lmA

w

26MLA120

~
~

-

~

10

0

2000

4000
6000
8000
10000 12000
NUMBER OF PULSES
FIGURE 9. REPETITIVE PEAK PULSE CAPABILITY

Capacitance
The ML suppressor is constructed by building up a composite assembly of alternate layers of ceramic material and
metal electrode. Since capacitance is proportional to area,
and inversely proportional to thickness, the lower voltage
ML:s have a relatively high capacitance. Typical values of
capacitance are shown in Table 2.
TABLE 2. TYPICAL CAPACITANCE VALUES FOR 1206 MULTILAYER FAMILY
CAPACITANCE (pF)
FREQUENCY (AT BIAS = 1Vp•p)
DEVICE TYPE

Size
A principal benefit of the new ML suppressor is their compact size in comparison to other surface mount components.
The ML suppressor could be up to 50 times smaller than the
components they are protecting. The small size of the ML
offers an advantage in the saving of circuit board real estate
and an ease in handling. Additionally, the solder mounting
pads required for ML are much smaller, resulting in even
more circuit board area savings.

1KHz

10KHz

100KHz

1MHz

V5.5MLA 1206

6250

5680

5350

5000

V14MLA1206

2750

2500

2360

2200

V18MLA1206

2100

1930

1830

1700

V26MLA1206

1000

910

860

800

V33MLA1206

600

550

520

500

V42MLA1206

550

520

480

450

V56MLA1206

410

380

360

350

V68MLA1206

190

170

160

150

Peak Current and Energy Capability
There are many design trade-offs involved in selecting the
best transient suppression device for a given application. As
previously mentioned, the large active electrode area available to the ML ensures that it's peak current handling capability is one of it's best features. Thus, by virtue of its
construction, the ML is capable of dissipating significant
amounts of energy over a small volume. The interdigitated
construction of the ML means that the very high temperatures resulting from a transient occurrence will be dissipated
through millions of P-N junctions. This is unlike a silicon suppressor, which has only one P-N junction available to handle
a peak transient. Additionally, because many different materials with varying thermal coefficients of expansion are
employed in the construction of a zener TVS, more extreme
thermal stresses are created in transient energy dissipation
and in the resulting temperature cycling. In an attempt to
overcome this shortcoming, a number of silicon die are
placed in series in a sandwich construction, with a metal
header to act as a heat sink and solder pellets for bonding
(Figure 10). This construction is designed to distribute the
transient energy in more than one P-N junction, and will
somewhat reduce the steep temperature build up. The reliability of such an approach is questionable. The metal sandwich is not completely effective in increasing the thermal
capacity for transient pulses below 50 microseconds,
because of the thermal time constant involved in transporting the energy (heat) from where it is generated (the silicon
die) to the metal heat sink. Though high energy transients
are much less frequent than low energy ones, it takes only
one transient to completely damage the transient protector,
and hence the component or circu it being protected. A
device with no other function than to keep dangerous transients away from components may become the source of the
problem if it shorts or opens, and leaves the circuit without
protection. In the ML TVS, millions of P-N junctions are an
integral part of the device structure, and it is this inherent
advantage which gives excellent thermal properties.

12-9

z
o
~re

~15

itz
D..

 10 Joules

Infrequent

< 125V
< 1 Joules

Often

-300V to +80V
< 1 Joule

Each Turn-Off

-1 OOV to -40V

Ignition Pulse,
Battery Disconnected

< 0.5 Joules

Mutual Coupling
in Harness

< 1 Joules

Ignition Pulse,
Normal

FREQUENCY
OF OCCURRENCE

<75V

< 500Hz Several Times in
Vehicle ute
Often

<200V
< 0.001 Joules < 500Hz Continuous
3V

Accessory Noise

< 1.5V

50Hz to 10kHz

Transceiver
Feedback

,,20mV

R.F.

Application Note 9108
Extension of Contact Life
When relays or mechanical switches are used to control
inductive loads, it is often necessary to derate the contacts
to SO% of their resistive load rating due to the wear caused
by the arcing of the contents. This arcing is caused by the
stored energy in the inductive load. Each time the current in
the inductive coil is interrupted by the mechanical contacts,
the voltage across the contacts increases until the contacts
arc. When the contacts arc, the voltage across the arc
decreases and the current in the coil can increase somewhat. The extinguishing of the arc causes an additional voltage transient which can again cause the contacts to arc. It is
not unusual for restriking to occur several times with the total
energy in the arc several times that which was originally
stored in the inductive load. It is this repetitive arcing that is
so destructive to the contacts. A ML can be used to prevent
initiation of the arc.
Knowing the energy absorbed per pulse, the pulse repetition
rate and the maximum operating voltage is sufficient to
select the correct size ML suppressor. It is necessary to
ensure that the device selected is capable of dissipating the
power generated in the cOil 9 .
Part Number Nomenclature
The part number of the ML device gives the following basic
information:

V33

MLA

1206

~

Maximum Non-Repetitive Surge Current (ITM): This is the
maximum peak current which may be applied for an 8120l1s
impulse (Figure 17), with the VM(DC) or VM(AC) voltage also
applied, without causing device failure. This pulse can be
applied to the ML suppressor in either polarity.
Maximum Non-Repetitive Surge Energy (WTM): This is
the maximum rated transient energy which may be dissipated
for a single current pulse of 10/1 OOOI1S, with the rated V M(DC)
or VM(AC) voltage applied, without causing device failure.
Maximum Clamping Voltage (Ve>: This is the peak voltage
appearing across the ML suppressor when measured for an
8/20l1s impulse and specified pulse current. The clamping
voltage is shown for a current range of 1 milliamp to SO amps
in the maximum transient V-I characteristic curves.
Leakage Current (10: This is the amount of current drawn
by the ML in its non-operational mode, i.e. when the voltage
applied across the ML does not exceed the rated VM(DC) or
V M(AC) voltage.
Nominal Voltage (VN(DCV: This is the voltage at which the
ML begins to enter its conduction state and suppress transients. This is the voltage defined at the 1 milliamp point and
has a minimum and maximum voltage specified.
Capacitance (C): This is the capacitance of the ML when
measured at a frequency of 1MHz with 1 volt peak-to-peak
voltage bias applied.

DEVtCE SIZE:

w

SERIES DESIGNATION:

...w

~100

1206 =0.120" x 0.060"
1210 =0.120" x 0.100"

~

Multilayer Suppressors

IL

MAXIMUM CONTINUOUS
WORKING VOLTAGE: VM(ocl

w

9ol----;{

~ 50r--~~-r-+---~
z

~

...w
TIME

Description of ML Ratings and Characteristics
MaxImum Continuous DC Working Voltage (VM(DC»: This
is the maximum continuous dc voltage which may be applied
up to the maximum operating temperature (+12S0C) of the
ML. This voltage is also used as the reference test point for
leakage current. This voltage is always less than the breakdown voltage of the device.
Maximum Continuous AC RMS Working Voltage (VM(AC»:
This is the maximum continuous sinusoidal rms voltage
which may be applied. This voltage may be applied at any
temperature up to + 12SoC.

12-13

0, = Virtual Origin of Wave
T =Time From 10% to 90% of Peak
T, =Virtual Front time =1.25 • t
T2 =Virtual Time to Half Value (Impulse Duration)
Example: For an 8I20j.ls Current Waveform:
8j.lS =T, =Virtual Front Time
20j.lS = T2 = Virtual Time to Half Value
FIGURE 17. CURRENT TEST WAVEFORM

Application Note 9108
Mountdown Recommendations
Soldering
The principal techniques used for the soldering of components in surface mount technology are Infra Red (IR) Reflow,
Vapour Phase Reflow and Wave Soldering. Before soldering, the board and components must first be cleaned. A I, I,
I, trichloroethane cleaning solvent in an ultrasonic bath, with
a cleaning time of 2-5 minutes, is recommended for this
operation. When wave soldering, the ML suppressor is
attached to the substrate by means of an epoxy resin. When
the epoxy adhesive is cured, the assembly is placed on a
conveyor and run through the soldering process. With IR and
vapour phase reflow the device is placed in a solder paste
on the substrate. As the solder paste is heated it reflows and
solders the unit to the board.

Once the soldering process has been completed, it is still
necessary to ensure that any further thermal shocks are
avoided. One possible cause of thermal shock is hot printed
circuit boards being removed from the solder bath and subjected to cleaning solvents at room temperature. The boards
must be allowed to cool to less than 50 degree celsius
before final cleaning.

With the ML suppressor, the recommended solder paste to
use is a 60/40 Tin/Lead (Sn/Pb). While this configuration is
best a solder paste a 62/36/2 (Sn/Pb/Ag) or a 63/37 (Sn/ Pb)
can also be used with excellent results.

(2) "Harris Semiconductor Application Note AN9003"

In soldering applications, the ML suppressor is held at elevated temperatures for a relatively long period of time. The
wave soldering operation is the most strenuous process, as
the components are immersed in the molten solder for several seconds. To avoid the possibility of stresses due to thermal shock occurring, a pre-heat stage in the soldering
process is recommended, and the peak temperature of the
solder bath should be rigidly controlled. When using the
reflow process, care should be taken to ensure that the ML
chip is never subjected to a thermal gradient steeper than 4
degrees per second; the ideal gradient being 2 degrees per
second. When soldering preheating to within 100 degrees of
the peak temperature is essential to minimize thermal shock.
Some examples of typical soldering conditions are given in
Table 4.

References
(1) "An Overview of Electrical Overstress Effects on Semiconductor Devices:' D.G. Pierce and D.L. Durgin, BoozAllen & Hamilton, Inc. Albuquerque, NM.

(3) "Protection of Electronic Circuits From Overvoltages",
Ronald B. Standler, 1989
(4) "ZnO Varistors for Transient Protection," L.M. Levinson,
and H.R. Phillip, IEEE Trans. Parts, Hybrids and Packaging, 13:338-343, 1977
(5) "ZnO Varistors for Protection Against Nuclear Electromagnetic Pulses:' H.R Phillip, and L.M. Levinson 1981
(6) "Overshoot: A Lead Effect in Varistor Characteristics,"
Fisher, FA, G.E. Company, Schnectady, NY. 1978
(7) "Harris Semiconductor Application Note AN9003"
(8) "Harris Semiconductor Application Note AN9002"
(9) "Transient Voltage Suppression Devices", Harris Semiconductor DB450C

TABLE 4. SOLDERING RECOMMENDATIONS
SOLDERING
OPERATION

IR Reflow

TIME
(SECONDS)

TEMPERATURE
<"C)

5 - 10

220

Wave Solder

3-5

260

Vapour Phase

5 - 10

222

12-14

Harris Semiconductor

-

- No. AN9211

Harris Varistor Technology

April1993

SOLDERING RECOMMENDATIONS FOR SURFACE MOUNT
METAL OXIDE VARISTORS AND
MULTILAYER TRANSIENT VOLTAGE SUPPRESSORS
Authors: Marty Corbett and Neil McLoughlin

Introduction
In recent years, electronic systems have migrated towards
the manufacture of increased density circuits, with the same
capability obtainable in a smaller package or increased
capability in the same package. The accommodation of
these higher density systems has been achieved by the use
of surface mount technology (SMT). Surface mount technology has the advantages of lower costs, increased reliability
and the reduction in the size and weight of components
used. With these advantages, surface mount technology is
fast becoming the norm in circuit design.
The increased circuit densities of modern electronic systems
are much more vulnerable to damage from transient overvoltages than were the earlier circuits, which used relays and vacuum tubes. Thus, the progress in the development of faster
and denser integrated circuits has been accompanied by an
increase in system vulnerability. Transient protection of these
sensitive circuits is highly desirable to assure system survival.
Surface mount technology demands a reliable transient voltage protection technology, packaged compatibly with other
forms of components used in surface mount technology.
Harris Semiconductor has led the field in the introduction of
surface mount transient voltage suppressors. These devices
encompass voltages from 3.5V DC to 275V AC and have a
wide variety of applications. Their size, weight and inherent
protection capability make them ideal for use on surface
mount printed circuit boards.
There are two standard series of Harris surface mount surge
suppressors. The CH SERIES metal oxide varistors which
encompass voltages from 14V DC to 275V AC and the new
ML SERIES which covers a voltage range from 3.5V DC to
68V DC.

Since the voltage across the MOV is held at some level
higher than the normal line voltage while surge current flows,
there is energy deposited in the varistor during its surge
diversion function.

FIGURE 1. V-I CHARACTERISTICS OF A MOV

The basic conduction mechanism of a MOV results from semiconductor junctions (P-N junctions) at the boundaries of the
zinc oxide grains. A MOV is a multi junction device with millions
of grains acting as a series parallel combination between the
electrical terminals. The voltage drop across a single grain in
nearly constant and is independent of grain size.
The CH series of surface mount metal oxide varistors are of
a monolayer construction in a 5mm by Bmm package size.
They are fully symmetrical and are passivated both top and
bottom (Figure 2). The main advantage of this technology is
its high operating voltage capability (68V DC to 275V AC).
The CH SERIES of metal oxide varistors are supplied in both
7" and 13" tape and reels.

Metal Oxide Varistors
A metal oxide varistor (MOV) is a non-linear device which
has the property of maintaining are relatively small voltage
change across its terminals while a disproportionately large
surge current flows through it (Figure 1). When the MOV is
connected in parallel across a line its non-linear action
serves to divert the current of the surge and hold the voltage
to a value that protects the equipment connected to the line.

Copyright © Harris Corporation t 993

12-15

c;; ::~~::::::~~~O,~
ZINC OXIDE
MATERIAL

END
TERMINATION

FIGU RE 2. CROSS-SECTION OF THE "CH" SERIES OF METAL
OXIDE VARISTORS

Application Note 9211
Multilayer Transient Voltage Suppressors
The Harris multilayer (ML) series of suriace mount surge
suppressors are of a multilayer construction. This technology, represents a recent breakthrough in its application to
transient voltage suppression.
The ML varistor is constructed by forming a combination of
alternating electrode plates and semiconducting ceramic
layers into a block. Each alternate layer of electrode is
connected to opposite end terminations (Figure 3). The
interdigitated block formation gre~tly enhances the available
cross-sectional area for active conduction of transients. This
paralleled arrangement of the· inner electrode layers represents significantly more active suriace area than the small
outline of the package may suggest. The increased active
suriace area results in proportionally higher peak energy
capability.

protect. The present size offerings are 1206,1210,1812 and
2220, with voltage ranges form 3.5V DC to 68V DC. Its
robust construction makes it ideally suitable to endure the
thermal stresses involved in the soldering, assembling and
manufacturing steps involved in suriace mount technology.
As the device is inherently passivated by the fired ceramic
material, it will not support combustion and is thus immune
to any risk of flammability which may be present in the
plastic or epoxy molded parts used in industry standard
packages.

Substrates
There are a wide choice of substrate materials available for
use as printed circuit boards in a suriace mount application.
The main factors which determine the choice of material to
use are:
1. Electrical Performance

INNER
EL:'ES \

2. Size and Weight Limitations

SEMICONDUCTING
CERAMIC

,. /'

\.

3. Thermal Characteristics

AI!m

4. Mechanical Characteristics
5. Cost

~

~

END
TERMINATION

FIGURE 3. INTERNAL CONSTRUCTION OF THE HARRIS MULTlLAYER TRANSIENT VOLTAGE SUPPRESSOR
A further advantage of this type of construction is that the
breakdown voltage of the device is dependent on the thickness between the electrode layers (dielectric thickness) and
not the overall thickness of the device.
The ML suppressor is a surface mountable device that is
much smaller in size than the components it is designed to

When choosing a substrate material, the coefficient of
thermal expansion of a Harris suriace mountable suppressor
of 6ppmfOC is an important consideration. Non-organic
materials (ceramic based substrates), like aluminum or berillia, which have coefficients of thermal expansion of
5-7ppmoC, are a good match for the CH andML series
devices. Table 1 oullines some of the other materials used,
and also their more important properties pertinent to suriace
mounting.
While the choice of substrate material should take note of
the coefficient of expansion of the devices. This may not be
the determining factor in whether a device can be used or
not. Obviously the environment of the finished circuit board
will determine what level of temperature cycling will occur. It
is this which will dictate the criticality of the match between
device and PCB. Currently for most applications, both the
CH and ML series use FR4 boards without issue.

TABLE 1. SUBSTRATE MATERIAL PROPERTIES
MATERIAL PROPERTIES
GLASS TRANSITION
TEMPERATURE (OC)

XY COEFFICIENT OF THERMAL
EXPANSION (ppmJOC)

THERMAL CONDUCTIVITY
(W/MOC)

Epoxy Fiberglass-FR4

125

14-18

0.16

Polyamide Fiberglass

250

12·16

0.35

Epoxy Aramid Fiber

125

6·8

0.12

FiberlTeflon Laminates

75

20

0.26

Not Available

5·7

21.0

SUBSTRATE STRUCTURE

Aluminium·beryillia (Ceramic)

12-16

Application Note 9211
Fluxes
Fluxes are used for the chemical cleaning of the substrate
surlace. They will completely remove any surlace oxides, and
will prevent re-oxidation. They contain active ingredients such
as solvents for removing soils and greases. Nonactivated
fluxes ("R" type) are relatively effective in reducing oxides of
copper, nickel or palladium/silver metallizations and are
recommended for use with the Harris surlace mount range.

TABLE 2. RECOMMENDED MOUNTING PAD OUTLINE
DIMENSION
SUPPRESSOR
FAMILY

Mildly activated fluxes ("RMA" type) have natural and
synthetic resins, which reduce oxides to metal or soluble
salts. These "RMA" fluxes are generally not conductive nor
corrosive at room temperature and are the most commonly
used in the mounting of electronic components.
The "RA" type (fully activated) fluxes are corrosive, difficult to
remove, and can lead to circuit failures and other problems.
Other non-resin fluxes depend on organic acids to reduce
oxides. They are also corrosive after soldering and also can
damage sensitive components. Water soluble types in
particular must be thoroughly cleaned from the assembly.
Environmental concerns, and the associated legislation, has
led to a growing interest in fluxes with residues that can be
removed with water or water and detergents (semi-aqueous
cleaning). Many RMA fluxes can be converted to water
soluble forms by adding saponifiers. There are detergents and
semi-aqueous cleaning apparatus available that effectively
remove most RMA type fluxes. Semi-aqueous cleaning also
tends to be less expensive than solvent cleaning in operations
where large amounts of cleaning are needed.

T+M

L-(M X 2)

0.020W
(W + 0.010)

5 X 8 CH Series

2.21
(0.087)

5.79
(0.228)

5.50
(0.216)

1206 ML Series

1.65
(0.065)

1.85
(0.073)

2.62
(0.103)

1210 ML Series

1.85
(0.073)

1.85
(0.073)

3.73
(0.147)

1812 ML Series

1.85
(0.073)

3.20
(0.126)

4.36
(0.172)

2220 ML Series

1.84
(0.073)

4.29
(0.169)

6.19
(0.240)

Solder Materials and Soldering
Temperatures

260...,..----_....

For the Harris Semiconductor range of surlace mount
varistors, nonactivated "R" type fluxes such as Alpha 100 or
equivalent are recommended.

6

250

;; 240

a:

~ 230

Land Pad Patterns

ffi

Q.

Land pad size and patterns are one of the most important
aspects of surface mounting. They influence thermal, humidity,
power and vibration cycling test results. Minimal changes (even
as small as 0.005 inches) in the land pad pattern have proven
to make substantial differences in reliability.
This design/reliability relationship has been shown to exist
for all types of designs such as in J lead, quadpacks, chip
resistors, capacitors and small outline integrated circuit
(SOIC) packages. Recommended land pad dimensions are
provided for some surlace mounted devices along with
formulae which can be applied to different size varistors.
Figure 4 gives recommended land patterns for the direct
mount ML and CH series devices.

I"

L - (M + 2) ..

i

I

~.: -------------m:
~

--I

w + 0.010

: OR O.020W

.. ...................... _,

I--T+M

T

FIGURE 4. FORMULA FOR SURFACE MOUNTABLE VARISTOR FOOTPRINTS

220

~ 210

....

200
5

10
TIME (SECONDS)

FIGURE 5. RECOMMENDED MAXIMUM TIME AND SOLDER
TEMPERATURE RELATIONSHIP OF HARRIS
MOVs

No varistor should be held longer than necessary at an
elevated temperature. The termination materials used in
both the CH and ML series devices are enhanced silver
based materials. These materials are sensitive to exposure
time and peak temperature conditions during the soldering
process (Figure 5). The enhanced silver formulation contains
either platinum, palladium or a mixture of both, which have
the benefit of significantly reducing any leaching effects
during soldering. To further ensure that there is no leeching
of the silver electrode on the varistor, solders with at least
2% silver content are recommended (62 Sn / 36 Pb /2 Ag).
Examples of silver bearing solders and their associated
melting temperatures are as follows:

12-17

Application Note 9211
TABLE 3. SILVER BEARING SOLDERS (ALPHA METALS)

The only difference between these two methods is the
process of applying heat to melt the solder. In each of these
methods precise amounts of solder paste are applied to the
circuit board at points where the component terminals will be
located. Screen or stencil printing, allowing simultaneous
application of paste on all required points, is the most
commonly used method for applying solder for a reflow
process. Components are then placed in the solder paste.
The solder pastes are a viscous mixture of spherical solder
powder, thixotropic vehicle, flux and in some cases, flux
activators.

MELTING TEMPERATURE
ALLOY

62 Sn 136 Pb 12 Ag
96.5 Sn 13.5 Ag

of

°C

355

179

430

221

95 Sn/5Ag

430·473

221·245

20 Sn 1 88 Pb 1 2 Ag

514-576

268·302

536

280

5 Sn 1 92.5 Pb 12.5 Ag

Soldering Methods
There are a number of different soldering techniques used in
the surface mount process. The most common soldering
processes are infra red reflow, vapor phase reflow and wave
soldering.
With the Harris surface mount range, the solder paste
recommended is a 62136/2 silver solder. While this
configuration is best, other silver solder pastes can also be
used. In all soldering applications, the time at peak
temperature should be kept to a minimum. Any temperature
steps employed in the solder process must, in broad terms,
not exceed 70°C to 80°C. In the preheat stage of the reflow
process, care should be taken to ensure that the chip is not
subjected to a thermal gradient of greater than 4 degrees per
second; the ideal gradient being 2 degrees per second. For
optimum soldering, preheating to within 100 degrees of the
peak soldering temperature is recommended; with a short
dwell at the preheat temperature to help minimize the
possibility of thermal shock. The dwell time at this preheat
temperature should be for a time greater than 101'1 seconds,
where T is the chip thickness in millimeters. Once the
soldering process has been completed, it is still necessary to
protect against further effects of thermal shocks. One
possible cause of thermal shock at the post solder stage is
when the hot printed circuit boards are removed from the
solder and immediately subjected to cleaning solvents at
room temperature. To avoid this thermal shock affect, the
boards must first be allowed to cool to less than 50°C prior to
cleaning.
Two different resistance to solder heat tests are routinely
performed by Harris Semiconductor to simulate any possible
effects that the high temperatures of the solder processes
may have on the surface mount chip. These tests consist of
the complete immersion of the chip in to a solder bath at
260°C for 5 seconds and also in to a solder bath at 220°C for
10 seconds. These soldering conditions were chosen to
replicate the peak temperatures expected in a typical wave
soldering operation and a typical reflow operation.

During the reflow process, the completed assembly is
heated to cause the flux to activate, then heated further,
causing the solder to melt and bond the components to the·
board. As reflow occurs, components whose terminations
displace more weight, in solder, than the components weight
will float in the molten solder. Surface tension forces work
toward establishing the smallest possible surface area for
the molten solder. Solder surface area is minimized when
the component termination is in the center of the land pad
and the solder forms an even fillet up the end termination.
Provided the boards pads are properly designed and good
wetting occurs, solder surface tension works to center
component terminations on the boards connection pads.
This centering action is directly proportional to the solder
surface tension. Therefore, it is often advantageous to
engineer reflow processes to achieve the highest possible
solder surface tension, in direct contrast to the desire of
minimizing surface tension in wave soldering.
In designing a reflow temperature profile, it is important that
the temperature be raised at least 20°C above .the melting or
liquidus temperature to ensure complete solder melting, flux
activation, jOint formation and the avoidance of cold melts.
The time the parts are held above the melting point must
belong enough to alloy the alloy to wet, to become homogenous and to level, but not enough to cause leaching of
solder, metallization or flux charring.
A fast heating rate may not always be advantageous. The
parts or components may act as heat sinks, decreasing the
rate of rise. If the coefficients of expansion of the substrate
and components are too diverse or if the application of heat
is uneven, fast breaking or cooling rates may result in poor
solder joints or board strengths and loss of electrical
conductivity. As stated previously, thermal shock can also
damage components. Very rapid heating may evaporate low
boiling point organic solvents in the flux so quickly that it
causes solder spattering or displacement of devices. If this
occurs, removal of these solvents before reflow may be
required. A slower heating rate can have similar beneficial
effects.
Infra Red Reflow

Reflow Soldering
There are two major reflow soldering techniques used in
SMTtoday:
1. Infra Red Reflow
2. Vapor Phase Reflow

Infra Red (IR) reflow is the method used for the reflowing of
solder paste by the medium of a focused or unfocused infra
red light. Its primary advantage is its ability to heat very
localized areas.
The IR process consists of a conveyor belt passing through
a tunnel, with the substrate to be soldered sitting on the belt.

12-18

Application Note 9211
The tunnel consists of three main zones; a non-focused preheat, a focused reflow area and a cooling area. The unfocused infrared areas generally use two or more emitter
zones, thereby providing a wide range of heating profiles for
solder reflow. As the assembly passes through the oven on
the belt, the timeltemperature profile is controlled by the
speed of the belt, the energy levels of the infrared sources,
the distance of the substrate from the emitters and the
absorptive qualities of the components on the assembly.
The peak temperature of the infrared soldering operation
should not exceed 220oC. The rate of temperature rise from
the ambient condition to the peak temperature must be
carefully controlled. It is recommended that no individual
temperature step is greater than BOoC. A preheat dwell at
approximately 150°C for 60 seconds will help to alleviate
potential stresses resulting from sudden temperature
changes. The temperature ramp up rate from the ambient
condition to the peak temperature should not exceed 4°C
per second; the ideal gradient being 2°C per second. The
dwell time that the chip encounters at the peak temperature
should not exceed 10 seconds. Any longer exposure to the
peak temperature may result in deterioration of the device
protection properties. Cooling of the substrate assembly
after solder reflow is complete should be by natural cooling
and not by forced air.
The advantages of IR Reflow are its ease of setup and that
double sided substrates can easily be assembled. Its biggest
disadvantage is that temperature control is indirect and is
dependent on the IR absorption characteristics of the component and substrate materials.
On emergence from the solder chamber, cooling to ambient
should be allowed to occur naturally. Natural cooling allows a
gradual relaxation of thermal mismatch stresses in the
solder joints. Forced air cooling should be avoided as it can
induce thermal breakage.
The recommended temperature profile for the IR reflow
soldering process is as Table 4 and Figure 6.
TABLE 4. RECOMMENDED TEMPERATURE PROFILE FOR IR
REFLOW SOLDER PROCESS
INFRA RED REFLOW
TEMPERATURE (OC)

TIME (SECONDS)

25-60

60

60-120

60

120-155

30

155-155

60

155-220

60

220-220

10

220-50

60

220
200
180

U

160

w

140

"a:!;(

120

~

a:

...:::;;w

W

0-

100
80
60
40
20

2
3
4
TIME (MINUTES)

5

6

FIGURE 6. TYPICAL TEMPERATURE PROFILE

Vapor Phase Reflow
Vapor phase reflow soldering involves exposing the
assembly and joints to be soldered to a vapor atmosphere of
an inert heated solvent. The solvent is vaporized by heating
coils or a molten alloy, in the sump or bath. Heat is released
and transferred to the assembly where the vapor comes in
contact with the colder parts of the substrate and then
condenses. In this process all cold areas are heated evenly
and no areas can be heated higher than the boiling point of
the solvent, thus preventing charring of the flux. This method
gives a very rapid and even heating affect. Further advantages of vapor phase soldering is the excellent control of
temperature and that the soldering operation is performed in
an inert atmosphere.
The liquids used in this process are relatively expensive and
so, to overcome this a secondary less expensive solvent is
often used. This solvent has a boiling temperature below
50°C. Assemblies are passed through the secondary vapor
and into the primary vapor. The rate of flow through the
vapors is determined by the mass of the substrate. As in the
case of all soldering operations, the time the components sit
at the peak temperature should be kept to a minimum. The
dwell time is a function of the circuit board mass but should
be kept to a minimum.
On emergence from the solder system, cooling to ambient
should be allowed to occur naturally. Natural cooling allows a
gradual relaxation of thermal mismatch stresses in the
solder joints. Forced air cooling should be avoided as it can
induce thermal breakage.
The recommended temperature profile for the vapor phase
soldering process is as Table 5 and Figure 7.

12-19

Application Note 9211
TABLE 5. RECOMMENDED TEMPERATURE PROFILE FOR
VAPOR PHASE REFLOW PROCESS

surface mount components, a defect called voiding (i.e.
skipped areas). One disadvantage of the high velocity turbu·
lent wave is that it gives rise to a second defect known as
bridging, where the excess solder thrown at the board by the
turbulent wave spans between adjacent pads or circuit
elements thus creating unwanted interconnects and shorts.

VAPOR PHASE REFLOW
TEMPERATURE (oC)

TIME (SECONDS)

25·90

8

90·150

13

150·222

3

222·222

10

222·80

7

80·25

10

The second, smooth wave accomplishes a clean up
operation, melting and removing any bridges created by the
turbulent wave. The smooth wave also subjects all previous
soldered and wetted surfaces to a sufficiently high
temperature to ensure good solder bonding to the circuit and
component metallizations.
In wave soldering, it is important that the solder have low
surface tension to improve its surface wetting characteristics.
Therefore, the molten solder bath is maintained at tempera·
tures above its liquid point.
On emergence from the solder wave, cooling to ambient
should be allowed to occur naturally. Natural cooling allows a
gradual relaxation of thermal mismatch stresses in the
solder joints. Forced air cooling should be avoided as it can
induce thermal breakage.

225
225

0"

200

w
a:

175

!a:a:

150

Do.

125

'L

The recommended temperature profile for the wave soldering process is as Table 6:

:I

w
::;;
W

I-

TABLE 6. RECOMMENDED TEMPERATURE PROFILE FOR
WAVE SOLDER PROCESS

100

WAVE SOLDER

75
50

TEMPERATURE (oC)

TIME (SECONDS)

25·125

60

125-180

60

180-260

60

260·260

5

260-180

60

180-80

60

80-25

60

25
5

10

1'5

20

25

30

35

40

45

50

TIME (SECONDS)

FIGURE 7. TYPICAL TEMPERATURE PROFILE

Wave Solder
This technique, while primarily used for soldering thru hole
or leaded devices inserted into printed circuit boards, has
also been successfully adapted to accommodate a hybrid
technology where leaded, inserted components and adhesive bonded surface mount components populate the same
circuit board.
The components to be soldered are first bonded to the
substrate by means of a temporary adhesive. The board is
then fluxed, preheated and dipped or dragged through two
waves of solder. The preheating stage serves many functions. It evaporates most of the flux solvent, increases the
activity of the flux and accelerates the solder wetting. It also
reduces the magnitude of the temperature change experienced by the substrate and components.
The first wave in the solder process is a high velocity
turbulent wave that deposits large quantities of solder on all
wettable surfaces it contacts. This turbulent wave is aimed at
solving one of the two problems inherent in wave soldering

Cleaning Methods and Cleaning Fluids
The objective of the cleaning process is to remove any
contamination from the board, which may affect the
chemical, physical or electrical performance of the circuit in
its working environment.
There are a wide variety of cleaning processes which can be
used, including aqueous based, solvent based or a mixture
of both, tailored to meet specific applications. After the
soldering of surface mount components there is less residue
to remove than in conventional through hole soldering. The
cleaning process selected must be capable of removing any

12-20

Application Note 9211
contaminants from beneath the surface mount assemblies.
Optimum cleaning is achieved by avoiding undue delays
between the cleaning and soldering operations; by a
minimum substrate to component clearance of 0.15mm and
by avoiding the high temperatures at which oxidation occurs.
Harris recommends 1, 1, 1 trichloroethane solvent in an
ultrasonic bath, with a cleaning time of between two and five
minutes. Other solvents which may be better suited to a
particular application and can also be used may include one
or more of the following:

TABLE 7. CLEANING FLUIDS
Water

Acetone

Isopropyl Alcohol

Fluorocarbon 113

Fluorocarbon 113 Alcohol Blend

N-Butyl

1, 1, 1 Trichloroethane Alcohol Blend

Trichloroethane

Toluene

Methane

been exposed to the molten solder material but the solder
has not adhered to the surface; base metal remains
exposed. The accepted criterion is that no more than 5% of
the terminated area should remain exposed after an immersion of 5 seconds in a static solder bath at 220°C, using a
nonactive flux.
Leaching:
This is the dissolving of the chip termination into the molten
solder. It commences at the chip corners, where metal
coverage is at a minimum. The result of leaching is a weaker
solder joint. The termination on the Harris surface mount
suppressors consist of a precious metal alloy which
increases the leach resistance capability of the component.
Leach resistance defined as the immersion time at which a
specified proportion of the termination material is visibly lost,
under a given set of soldering conditions.
De-Wetting:
This condition results when the molten solder has coated the
termination and then receded, leaving irregularly shaped
mounds of solder separated by areas covered with a thin solder film. The base metal is not exposed.

Solder Defects

References

Non-Wetting:

1. Transient Voltage Suppression
(08450.2), Harris Semiconductor

This defect is caused by the formation of oxides on the
termination of the components. The end termination has

Devices

Manual

2. CANE SMT 2588, Syler Technology Limited, UK.

z

o

~ffi
~b
~z

Q.

c(

12-21

Harris Semiconductor

--

-

- No. AN9304.1

Harris Intelligent Power

August 1993

ESD AND TRANSIENT PROTECTION USING THE SP720
Author: Wayne Austin
The need for transient protection in integrated circuits is
driven by the quest for improved reliability at lower cost. The
primary efforts for improvement are generally directed
toward the lowest possible incidence of over-voltage related
stresses. While electrical over-stress (EOS) is always a
potential cause for failure; a discipline of proper handling.
grounding and attention to environmental causes can reduce
EOS causes for failure to a very low level. However, the
nature of hostile environments cannot always be predicted.
Electrostatic Discharge (ESD) in some measure. is always
present and the best possible ESD interface protection may
still be insufficient. As the technology of solid state
progresses. the occurrence of ESD related IC failures is not
uncommon. There is a continuing tendency for both ESD
and EOS failures, due in part. to the smaller geometries of
today's VLSI circuits.
The solid state industry has generally acknowledged a standard for the level of capability in LSI designs of ±2000V for
the Human Body Model where the defined capacitance is
100pF and the series resistance is 1500n. However, this
level of protection may not be adequate in many applications
and can be difficult to achieve in some VLSI technologies.
Normal precautions against ESD in the environment of
broad based manufacturing are often inadequate. The need
for a more rugged IC interface protection will continue to be
an established goal.
Historically, it should be recognized that early IC development began to address the ESD problem when standards for
handling precautions did not exist. High energy discharges
were a common phenomena associated with monitor and
picture tube (CRT) applications and could damage or
destroy a solid state device without direct contact. I! was
recognized that all efforts to safe-guard sensitive devices
were not totally sufficient. Small geometry signal processing
circuits continued to sustain varying levels of damage
through induced circulating currents and direct or indirect
exposure in handling. These energy levels could be
substantially higher than the current standard referenced in
Mil-Std-3015.7; also referred to as the Human Body Model.

and peripherals. telecommunication equipment and consumer electronic systems. While some IC's may only see the
need for ESD protection while in manufacturing assembly or
during service in the field. the most common cause for ESD
failures can still be related to a human contact. Moreover.
educational efforts have improved teday's manufacturing
environment substantially reduce failures that relate to the
mechanical handling. The ESD failure causes that relate to
mechanical handling now have a test standard referred to as
a Machine Model which relates to the source of the
generated energy.
While the electrical model for an energy source is generally
accepted as a capacitor with stored charge and a series
resistance to represent the charge flow impedance. the best
means to handle the high energy discharge is not so clearly
evident. The circuit of Figure 1 illustrates the basic concept
that is applied as a method of ESD testing for the Human
Body Model. The ESD energy source is shown as a charged
capacitor CD and series connected, source impedance.
resistor R[)o The point of contact or energy discharge is
shown, for test purposes, as a switch external to the IC. A
protection structure is often included on an IC to prevent
damage from an ESD energy source. To properly protect the
circuit on the IC the on-chip switch, Ss, is closed when a
discharge is sensed and shunts the discharge energy
through a low impedance resistor (Rs) to ground. I! is
imperative that the resistance of the discharge path be as
low as practical to limit dissipation in the protection structure.
I! is not essential that the ground be the chip substrate or the
package frame. The energy may be shunted via the shortest
path external to the chip to an AC or DC ground.

The recognized need for improved ESD protection was first
precipitated under harsh handling conditions; particularly in
applications that interfaced to human contact or from the
interaction of mechanical parts in motion. The popular
features of component and modular electronic equipment
have continued to generate susceptibility to IC damage while
in continuing use. These market items include computers

Copyright © Harris Corporation 1993

12-22

POINT OF
ENERGY
DISCHARGE

fl
\

........

ESD
ENERGY
SOURCE

{l_

Co

ED

,----------i

Ro

"
~

;! :
:

~-C~~~~

-20Mn

ACTIVE :
,
CIRCUIT :

iSS Rs ,----------,

-=

(VERY LOW
RESISTANCE)
IC{CHIP)

FIGURE 1. ESD TEST FOR AN ON-CHIP PROTECTION CIRCUIT
USING THE MIL-STD-883. METHOD 3015.7 (HUMAN
BODY MODEL)

Application Note 9304
This conceptual method has been used in many IC designs
employing a wide variation of structures, depending the IC
technology and degree of protection needed. The switch, Ss
is generally a threshold sensitive turn-ON at some voltage
level above or below the normal signal range; however, it
must be within the a safe operating range of the device
being protected. The resistance, Rs is shown as the inherent
series resistance of the protection structure when it is
discharging (dumping) the ESD energy. In its simplest forms,
the protection structures may be diodes and zeners, where
the sensing threshold is the forward turn-ON or zener
threshold of the device. The inherent resistance becomes
the bulk resistance of the diode structure when it is conducting. Successful examples of two such protection structures
that have been used to protect sensitive inputs to MOS
devices are shown in Figure 2. The back-to-back zener
structure shown for the dual-gate MOSFET was employed in
the 3N - dual gate MOS devices before IC technology was
firmly established. The series poly and stacked diode
structure used to shunt ESD energy followed several
variations for use in CMOS technology and was employ in
the CD74HC/HCT - High Speed CMOS family of logic
devices. This CMOS protection structure is capable of meeting the 2000V requirements of Mil-Std-883, Method 3015.7;
where the Ro in Figure 1 is 15000 and Co is 100pF.

The switching arrangement for a basic and simple protection
structure is shown in Figure 3. Each high side and low side
protection structure (Rs and Ss) is an embedded device,
taking advantage of the P substrate and epitaxial N material
used in bipolar technology. Each cell contains an SCR with a
series dropping resistor to sense an over-voltage turn-ON
condition and trip the SCR (Switch Ss) into latch. The ONresistance (Rs) of the latched SCR is much lower than Ro
and, depending on the polarity of the ESD voltage, dumps
energy from the input signal line through the positive or negative switch to ground. The return to ground for either ESD
polarity is not limited by voltage supply definition, but may be
to positive or negative supply lines, if this suits the needs of
the application. When the energy is diSSipated and forward
current no longer flows, the SCR automatically turns-OFF.

..r--------------------,.. ..;. . -------

:i :l::
: PROTECTION CIRCUIT:

RS!!

Ss::

-+-----+--...,.f-t-:JVI,,.,,....S
•• :• ACTIVE
NEGATIVE
S::
CIRCUIT

:::5

o

Mr_-.

POSI~VE

PROTECTION
SIGNAL O-....
INPUT {
Ro

vee

INPUT O--JoIoI/Ir-+.......

:

TO
LOGIC

f~ L=:=:.t.l L. . ..

FIGURE 3. ESD AND TRANSIENT PROTECTION CIRCUIT

POLYR

'---'-----t s
FIGURE2. ESDANDTRANSIENT PROTECTION EFFECTIVELY
USED IN MOS AND CMOS DEVICES

Due to greater emphasis on Reliability under harsh application conditions, more ruggedized protection structure have
been developed. A variety of circuit configurations have
been evaluated and applied to use in production circuits. A
limited introduction to this work was published in various
papers by l. Avery (See Bibliography). To provide the best
protection possible within economic constraints, it was
determined that SCR latching structures could provide very
fast turn-ON, a low forward on resistance and a reliable
threshold of switching. Both positive and negative protection
structures were readily adapted to bipolar technology. Other
defining aspects of the protection network included the
capability to be self-protecting to a much higher level than
the signal input line being protected. Ideally, when a
protection circuit is not otherwise needed, it should have no
significant loading effect on the operating circuit. As such, it
should have very little shunt capacitance and require
minimal series resistance to be added to the signal line of
the active circuit. Also, where minimal capacitance loading is
essential for a fast turn-ON speed, the need for a simpler
structure is indicated.

Figure 4 shows the diagram of a positive and negative cell
protection circuit as it applies to the SP720. The PNP and
NPN transistor pairs are used as the equivalent SCR
structures. Protection in this structure allows forward turnON to go marginally above the +V supply to turn-ON the
high-side SCR or marginally below the -v supply to turn-ON
the low-side SCA. The signal line to the active device is
protected in both directions and does not add series impedance to the signal input line. A shunt resistance is used to
forward bias the PNP device for turn-ON but is not directly
connected to the signal line. As an on-Chip protection cell,
this structure may be next to the input pad of the active
circuit; which is the best location for a protection device.
However, for many applications, the technology of the active
chip may not be compatible to structures of the type
indicated in Figure 4. This is particularly true in the high
speed CMOS where the substrates are commonly N type
and connected to the positive supply of the chip. The protection cell structure shown in Figure 4 is not required to be on
the active chip because it does not sense series input
current to the active device. The sense mechanism is
voltage threshold referenced to the V+ and V- bias voltages.
The cell structure of the SCR pair of Figure 4 are shown in
the layout sketch and profile cutouts of Figure 5. It should be
noted that the layout and profiles shown here are equivalent
structures intended for tutorial information. The structures
are shown on opposite sides of the 'IN" chip bonding pad, as
is the case for the SP720. As needed for a preferred layout,
the structures are adjacent to the pad and as close to the

12-23

Application Note 9304
~~_---+V

__ ,_<>e_,

positive and negative supply lines as possible. The common
and best choice for effective layout is to provide a ground
ring (V-) around the chip and to layout with minimum distance paths to the positive supply (V+). In the SP720 the Vline is common to the substrate and frame ground of the IC.
The equivalent circuit diagram of the SP720 is shown in
Figure 6. Each switch element is an equivalent SCR
structure where 14 positive and negative pairs as shown in
Figure 4 are provided on a single chip. Each positive switching structure has a threshold reference to the V+ terminal,
plus one VSE (based-to-emitter voltage equal to one diode

: . - - - EQUIVALENT
:
SCR CIRCUIT

,, '

~--

J-..:

SIGNALo-_-.._....
INPUT

,:

. -------",

ACTIVE
CIRCUIT

:

,:

~----------!

----4>---V
FIGURE 4. PROTECTION CELLS OF THE SP720 SCR ARRAY

METAL CONTACT

Iwlk\!$_
B&R(P)

~
~N+)
ISO (P+)

1·.·."'.··,.1
EPI(N)

c::::::::J

--+'f¥-.... V+

V-

B
FIGURE SA.

~
A
N
HIGH AND LOW CELL PAIR LAYOUT; SHOWN WITHOUT PROTECT, METAL AND FIELD
OXIDE LEVELS (NOT TO SCALE)

V-

FtGURE 58. PROFILES OF THE HIGH AND LOW SIDE SP720 SCR PROTECTION PAIR (NOT TO SCALE)

12-24

Application Note 9304
forward voltage drop). Similarly, each negative switching pair
is referenced to the V- terminal minus one VSE '
The internal protection cells of the SP720 are directly
connect to the on-chip power supply line (+V) and the
negative supply line (-V), which are substantial in surface
metal content to provide low dropping resistance for the high
peak currents encountered. Since both positive or negative
transients can be expected, the SCR switches direct the
positive voltage energy to V+ and the negative voltage
sourced energy to V- (substrate) potential to provide fast
turn-ON with low ON resistance to protect the active circuit.

defined in the data sheet. For voltage, the static DC and
short duration transient capability is essentially the same.
The process capability is typically better than 45 volts,
allowing maximum continuous DC supply ratings to be
conservatively rated at 35 volts. The current capability of any
one SCR section is rated at 2A peak but is duration limited
by the transient heating effect on the chip. As shown in
Figure 7, the resistance of the SCR, when it is latched, is
approximately 0.96n and the SCR latch threshold has 1.08V
of offset. For EOS, the peak dissipation can be calculated as
follows:
For:

2A Peak Current, Ro = 1500n,

Then: VIN(PK) = 1.08V (Offset) + (0.96n x 2A) = 3V
The peak dissipation is Po
2.5

=3V x 2A =6 Watts

TA= +2S 0 C
(SINGLE PULSEO CURVE)

2 f

u

/

II:
U


(!l

z

Ii:
~350

o

(RATED FOR 20 SURGES)
300~-L--~-L--~~--~~--~--~~--~-"

o 10 20 30 40 50 60 70 80 90 100 110 120
NUMBER OF SURGES

FIGURE 1. TYPICAL REPETITIVE SURGE CURRENTCAPABILITY OF "C" III SERIES MOVs

As well as the surge current withstand test, UL Standard
1449 also has requirements for suppressor performance in a
repetitive surge environment. The duty-cycle transient
withstand test capability peak voltage and current levels are
6kV and 500A for both the cord and plug connected and
direct plug in suppressors. For the permanently wired
receptacle outlet the test levels are 6kV and 750A. In all
cases the duty-cycle test requirements are for a total of 24
pulses, 12 in alternating directions.
In the case of the 2Dmm size varistors, used for the
permanently wired receptacle suppressors, their repetitive
surge capability at 750A is 120 times. For the 14mm series of
devices, used in cord and plug connected and direct plug in
suppressors, the repetitive surge withstand capability is 80
pulses at 750 amps and 150 pulses at 500 amps. As in the
previous case, this rating is conservative. Continued stress testing at the 750A level has shown an inherent device capability
which commonly is in excess of 250 pulses. See Figure 2.

The maximum surge withstand capability of 6kV, 3kA is
proposed for cord and plug connected, direct plug in and
permanently wired receptacle outlet type transient voltage
surge suppressors. These peak transients are applied to the
suppressor a total of three times, with normal line voltage
also applied.

600r-----r-----r----;r----;r---~----_,

c(

~

~

W

(!l

V175LA20C
5501-----1-----1----I1----It- 750A (8120118 )
5001-----1-----1----If----If----I1----1

t!i
:oJ 4501-----1-----1----11----11----11----1
51

The peak surge current rating of the new 20mm 'C' III series
of Harris metal oxide varistors is 9000 amps. This series of
varistors are generally used for the permanently wired
receptacle suppressors. Under the surge current withstand
test requirements of UL Standar~ 1449 (3 pulses of 3kA)
these devices have a conservative rating of 20 such pulses.
Continued stress testing at this level has shown an inherent
device capability which commonly in excess of 100 pulses.
See Figure 1.
The peak surge current rating of the new 14mm series of
Harris metal oxide varistors is 6000 amps. This series of
varistors are generally used for both the cord and plug
connected and direct plug in types of suppressors. Under
the surge current withstand test requirements of UL
Standard 1449 (3 pulses of 3kA) these devices have a
conservative rating of 10 such pulses. Continued stress testing of these components at this level has shown an inherent
device capability commonly is in excess of 40 pulses.

V130LA20C
3kA (8120118)

~

~ 4001-----1-----1----If----If----I1----1

Ii:

::z

j 3501-----t-----t----II----II-----tr---'""'I
o
(RATED FOR 80 SURGES)

300

~

o

__--'____--'-____....L.____- ' -____
50
100
150
200
250

~

_ ___J

300

NUMBER OF SURGES

FIGURE 2. TYPICAL REPETITIVE SURGE CURRENT CAPABILITY OF "C" III SERIES MOVs

The transient surge rating serves as an excellent figure of
merit for the 'C' III suppressor. This extremely high, inherent
surge handling capability is one of the new 'C' III
suppressor's best features. The enhanced surge absorption
capability results from improved process uniformity and
enhanced construction. The homogeneity of the raw material
powder and improved control over the sintering and
assembly processes are contributing factors to this
improvement.

12-29

Application Note 9306
AC Bias Reliability
The 'C' III series of metal oxide varistors were designed for
use on the AC power line. The varistor is connected across
the line and is biased with a constant amplitude sinusoidal
voltage. If the varistor let throughlleakage current increases
with time. the power dissipation will also increase. with the
ultimate possibility of thermal runaway and varistor failure. It
should be noted that the definition of failure is a change in
the nominal varistor voltage (V N) exceeding ± 10%. with an
associated increase in the leakage current drawn by the
MOV. Although this type of varistor is still functioning
normally after this magnitude of change. devices at the lower
extremities of VN tolerance may begin to dissipate more
power.
To guard against this possibility. an extensive series of
statistically designed tests were performed to determine the
reliability of the 'C' '" type of varistor under AC bias
combined with high levels of temperature stress. To date.
this test has generated over 50,000 device hours of
operation at a temperature of 125°C. This temperature was
selected in order to accelerate the stress testing, although
the 'C' '" series are only rated at 85°C. Changes in the
nominal varistor voltage. measured at 1 milliamp, of less
than 2% have been recorded. See Figure 3.
300r-~--'---r-~--'---r-~--'-~r--r~

250~-+--4---~-+--4-~~-+--4-~~-+--4

__ __L--L__ __
100 200 300 400 500 600 700 800 900 1000 1100

100~~--~--L-~

o

~

~

L--L~

TIME (HOURS)

FIGURE 3. HIGH TEMPERATURE OPERATING LIFE +125°C
FOR 1000 HOURS AT RATED BIAS

Device Comparisons7• 8
A range of standard varistors. avalanche diodes, gas tube
arresters and filter capacitors were evaluated under a 6kV,
0.5Jls x 100kHz ring wave. This transient replicates that
called out in location Category A of the ANSI/IEEE C62.41.
where most cord and plug connected and direct plug in
suppressors are used. and is the most benign condition
expected in this location. All of the selected devices are
rated for use on a 120V AC line. The results obtained from
this evaluation are per Table 2. The conclusions from this
evaluation were: a) the silicon avalanche diode had the
lowest level of performance; b) since location Category A is
the location requiring the smallest sized suppressor, how
can a device which does not survive this testing be
considered an adequate suppressor?
Not only does the avalanche diode fail, but it is also very
expensive when compared with an equivalently rated metal

oxide varistor. There are avalanche diodes available. in the
15kW family. which absorb large amounts of energy and it is
assumed that these devices will meet the transient requirements of this test. From a cost comparisons. these devices
may be 15 - 20 times more expensive than an equivalent
MOV.
TABLE 2. COMPARATIVE PERFORMANCE DATA8 (NOTE:
THE LOWER THE PROTECTION LEVEL IS THE
BETTER)
DEVICE
PART.

AVERAGE
PROTECTION
LEVEL (kV)

FAILS I
SAMPLE
SIZE

Metal Oxide
Varistor

V130LAI
V130LA5
V130LA10A

0.51
0.50
0.47

0110
0110
0110

Silicon Ava·
lanche Diode

1.5KE200C

0.48

2110

Gas Tube Surge
Arrester

CG2230

0.67

0110

Filter Capacitor

C280AEA4K7

1.30

0110

PROTECTION
TECHNOLOGY

One of the primary requirements for a device rated for suppression of transients on the AC mains is its ability to handle
large amounts of energy. In order for a device to have a high
energy handling capability, it requires a large amount of bulk
material with a high specific heat value in the immediate
vicinity of the P-N junctions. The primary material in a metal
oxide varistor is zinc oxide and the average grain size for a
MOV used in an AC application is 20 microns. Observations
over a range of compositional variations and processing
conditions show a fixed voltage drop of between 2-3 volts
per grain with boundary junctions evenly distributed along
their edges. In the case of a 14mm varistor. part
V130LA10C, it would have an approximate volume of
220mm 3 of material in the immediate vicinity of the PN grain
junctions. An equivalent silicon avalanche diode would have
approximately 0.106mm 3 in their single P-N junction vicinity.
Comparing the volume of the varistor and the diode in the
immediate vicinity of the junction, the varistor has more than
2000 times a larger mass available. Thus, the peak temperature in the bulk material of the varistor per energy absorbed
is much lower than that for the single silicon avalanche diode
junction. It is the millions of P-N junctions, which are an
integral part of the mov structure, that gives it excellent
thermal and energy handling properties.

Reliability Performance of "C" 11/ Series
MOVs
While the electrical ratings and characteristics of the 'C' III
series of MOVs are conservatively rated. samples of these
devices have been subjected to a number of additional
electrical and environmental stresses, over and above those
specified. The results of this testing show an enhanced
device performance. A summary of the reliability tests
performed on the 'C' "' series are shown in Table 3.

12-30

Application Note 9306

"e" 11/ MOV Terms and Descriptions

TABLE 3. RELIABILITY TEST PERFORMANCE OF "C" III
SERIES MOVS
TEST
Surge
Current

REFERENCE
STANDARD

TEST CONDITIONS

TEST
RESULTS

UL 1449 IEEE! 9000 Amps (8120IlS)
ANSI C62.41
1 Pulse
IEC 1051
6500 Amps (8I20IlS)
2 Pulses

01165

3000 Amps (8/2OIlS)
20 Pulses

0175

750 Amps (8/201lS)
120 Pulses

0165

UL 1449 IEEE! 90 Joules (2ms)
ANSI C62.41
1 Pulse
IEC 1051

0/1258

Operating
Life

Mil-Std-202
Method 2040

125°C, 1000 Hours,
Rated Bias Voltage

0/180

120% Maximum
Rated Varistor
Voltage For 300s

0170

Temporary NlA
Overvoltage

Maximum Non-Repetitive Surge Current (ITM) - This is the
maximum peak current which may be applied for an Bl20llS
impulse, with rated line voltage also applied, without causing
device failure.

01105

Surge
Energy

Rated AC Voltage (VM(AC)RMS) - This is the maximum continuous sinusoidal voltage which may be applied to the MOV.
This voltage may be applied at any temperature up to the
maximum operating temperature of +85 0 C.

Maximum Non-Repetitive Surge Energy (WTM) - This is the
maximum rated transient energy which may be dissipated for
a single current pulse at a specified impulse and duration
(2ms), with the rated rms voltage applied, without causing
device failure.
Nominal Voltage (VN(DC)) - This is the voltage at which the
device changes from the off state to the on state and enters
its conduction mode of operation. This voltage is characterized at the 1 milliamp point and has specified minimum and
maximum voltage levels.
Clamping Voltage (Vel - This is the peak voltage appearing
across the MOV when measured at conditions of specified
pulse current amplitude and specified waveform (8/20IlS).

Device Selection
After evaluating the advantages and disadvantages of the
various suppression technologies available, the device of
choice is clearly the metal oxide varistor. Once the decision
has been made as to which technology to use, it is now
necessary to decide on the actual device to select for a
particular application. To select the correct varistor for a
specific application, determine the following information:
1. The maximum system RMS voltage
2. How the MOV is to be connected?
3. The MOV rating with a voltage 10-25% above system
voltage
4. The worst-case transient energy that will need to be
absorbed by the MOV. (Use the guidelines called out in
ANSI/IEEE C62.411992)

References
1. 'ANSI/IEEE C62.411992 Guide On Surge Voltages In
Low Voltage AC Power Circuits'.
2. 'Voltage Transients and Their Suppression', Corbett, M.,
3. 'Understanding AC Line Transient Immunity', Dash, G.
and Straus, I.,
4. 'Suppression Of Voltage Transients Is An Art Trying To
Be A Science', GE 660.33
5. 'The Propagation and Attenuation of Surge Voltages and
Currents in Low Voltage AC Circuits', Martzloff, F.D.,
1984

5. The clamping voltage required for system protection

6. 'Transient Voltage Suppression Devices', Harris Semiconductor DB450.2

Device Features

7. 'Protective Level Comparison of Voltage Transient Suppressors', Hopkins, D.C.

• Recognized as 'Transient Voltage Surge Suppressors' to
UL 1449; File E75961

8. 'Comparison of Transient Suppressors!', Korn, S.

• Recognized as "Transient Voltage Surge Suppressors' to
CSA C22.2, No.1; File LR91788
• High energy absorption capability: WTM = 45 to 120 joules
(2ms).
• High peak pulse current capability: ITM = 6000 to 9000
amps (8/20IlS)
• Wide operating voltage range: VM(AC)RMS = 130 to 175
volts
Available in tape and reel for automatic insertion; also
available with trimmed and/or crimped leads.

12-31

Harris Semiconductor

No. AN9307

Harris MOVs

April 1993

THE CONNECTOR PIN VARISTOR FOR TRANSIENT VOLTAGE
PROTECTION IN CONNECTORS
Authors: Paul McCambridge and Martin Corbett

Introduction
Nonlinear devices have long been used for transient voltage
protection and have bee available in conventional package
configurations - axial. radial. and power packages (Figure 1)
The connector pin varistor represents a new approach to
transient suppression by forming the active material into a
shape which requires no leads or package (Figure 2) The
idea was developed many years ago. but only recently have
breakthroughs in the manufacturing process allowed costeffective production of such devices.

an extremely low value. limiting the voltage rise across the
varistor (Figure 3). The destructive energy is absorbed by
circuit impedance and varistor impedance. Energy is
converted into hear and. if the varistor is properly rated. no
components are harmed.
+V

,,

i

~

~+-------~----~----~-------.

I

-V

FIGURE 3. VOLTAGE IMPEDANCE CHARACTERISTICS OF A
TYPICAL VARISTOR

To obtain the lowest clamping voltage. the impedance of the
varistor (Z8) and the impedance of the varistor leads (Ze>.
should be as low as possible. but the impedance of the line
(ZL) and the transient source (ZT) should be as high as possible (Figure 4). The part of ZL which is contributed by the
ground return also reduces ZL. but at the same time lifts the
ground above true ground and therefore should be small.
Unfortunately. the impedance of the transient source (ZT)
cannot be controlled and is unknown in most instances. 1

FIGURE 1. CONVENTIONAL PACKAGE CONFIGURATIONS

CROSS SECTION

~=~

[J···· .. ·····JDJ ~
~

~

.............. -.

ZT

~

FIGURE 2. TUBULAR VARISTOR (CONNECTOR PIN VARISTOR)

Connector pin varistors are voltage dependent nonlinear
semiconducting devices having electrical behavior similar to
back-to· back zener diodes. The symmetrical sharp breakdown characteristic enables the varistor to provide excellent
transient suppression. As the voltage of a transient rises. the
impedance of the varistor changes from a very high value to
Copyright © Harris Corporation 1993

12-32

COMPONENT
OR SYSTEM
TO BE
PROTECTED

ZL UNE
IMPEDANCE
ZT TRANSIENT
SOURCE
IMPEDANCE
Ze CONNECTION
IMPEDANCE
Zs SUPPRESSOR
IMPEDANCE
Ve CLAMPING
VOLTAGE
VT TRANSIENT
VOLTAGE

FIGURE 4. IMPEDANCE RELATIONSHIP IN A TRANSIENT
SUPPRESSOR CIRCUIT

Application Note 9307
Varistors contain zinc oxide, bismuth, cobalt, manganese
and other metal oxides. The structure of the body consists of
conductive zinc oxide grains surrounded by a glassy layer
(the grain boundary) which provides the 2.5V PN-junction
semiconductor characteristics. Figure 5 shows a simplified
cross section of the varistor material.

Due to the varistor capacitance (C p), the varistor is initially a
short circuit to any applied pulse. Varistor breakdown
conduction through (V B1 ) and (V B2 ), as illustrated in Figure 6
does not occur until this capacitor is charged to the varistor
breakdown voltage (VB)' The time is calculated by:
te = C p

0

(V Bl/i) or (2)

Where i is the average pulse current (capacitor charging
current) for 0 ~ t ~ te. The value of the peak current is
controlled by = (di/dt) 0 Cp the source impedance voltage of
the transient, and the varistor'S dimensions (area proportional to C).

r

DEPLETION
REGION

THICKNESS

For longer duration pulses t > te , V Bl and V B2 will participate
on the current conduction process, as the voltage on C p
rises above the breakover voltage (VB)'
FIGURE 5. SIMPLIFIED MICROSTRUCTURE OF A VARISTOR
MATERIAL

The varistor is a multi-junction device with many junctions in
parallel and series. Each junction is heat sunk by zinc oxide
grains resulting in low junction temperatures and large overload capabilities.
As shown in Figure 5, the more junctions that are connected
in series, the higher the voltage rating and as more junctions
are connected in parallel, the higher the current rating.
Energy rating, on the other hand, is related to both voltage
and current and is proportional to the volume of the varistor.
In summary:

Speed of Response
The conduction mechanism is that of a II - VI polycrystalline
semiconductor. Conduction occurs rapidly, with no apparent
time lag even in the picosecond range.
Figure 7 shows a composite photograph of two voltage
traces with and without a varistor connected to a low-inductance high speed pulse generator having a rise time of 500
picosecond. The second trace is not synchronized with the
first, but merely superimposed on the oscilloscope screen,
showing the instantaneous voltage clamping effect of the
varistor. There is no delay or any indication which would justify concern about response time.

• Thickness is proportional to voltage
• Area is proportional to current (a x b) or [(d2 o1t)/4] or
(d 0 1t • length).
• Volume is proportional to energy (area x thickness)

Electrical Characteristics

TRACE 1
LOAD
VOLTAGE
WITHOUT
VARISTOR

::;

An electrical model for a varistor is represented by the
equivalent circuit shown in Figure 6.

~

!:;

g

TRACE 2
LOAD
VOLTAGE
CLAMPED

0

~

BY

VARISTOR

500 PICOSECONDS/DIV.

cp

FIGURE 7_ RESPONSE OF A VARISTOR TO A FAST RISING
PULSE (dv/dt = 1 MILLION VOLTS/IlS)

ROFF

Using conventional lead-mounted varistors, the inductance
of the leads completely masks the fast action of the varistor;
therefore, the test results as shown in Figure 7 required the
insertion of a small piece of varistor material in a coaxial line
to demonstrate the intrinsic varistor response.

FIGURE 6_ VARISTOR EQUIVALENT CIRCUIT

Pulse Response
The pulse response of a varistor is best understood by using
the equivalent circuit representation consisting of a pure
capacitor (C p), two batteries, the grain resistance (RZno) and
the intergrain capacitance (C INT ). The off-resistance (ROFF )
is not applicable in this discussion.

Tests made on lead-mounted devices, even with careful
attention to minimize lead length, show that the voltage
induced through lead inductance contributes substantially to
the voltage appearing across the varistor terminals (Figure
8). These undesirable induced voltage are proportional to
lead inductance and dildt and can be positive or negative.

12-33

Application Note 9307
TABLE1.INDUCEDVOLTAGEIN1IN.LEADS.PEAKCURRENT
lOA, AT DIFFERENT CURRENT RISE TIMES.

t

c

TIME

+

t
Vc

Vc = CLAMPING VOLTAGE

t
FIGURE 8. THE ELECTRICAL EQUIVALENT OF A LEADMOUNTED VARISTOR
Figure 9 shows the positive and negative part of the induced
voltage, resulting from a pulse with a rise time of 4ns to a
peak current of 2.5A. When the measurement is repeated
with a lead less varistor, such as the connector pin varistor,
its unique coaxial mounting allows it to become part of the
transmission line. This completely eliminates inductive lead
effect (Figure 10)
Calculations of the induced voltage as a direct result of lead
effect for different current rise times provides a better understanding of the dildt value at which the lead effect become
significant. Table 1 is based on an assumption of a current
pulse of lOA, 1 inch of lead wire (which translates into
approximately 15nH) and rise times ranging from seconds to
femtoseconds ..

1 sec.

lOA

15nH

150 x 10.9

1 X 10.3

lms

lOA

15nH

150 x 10.5

1 X 10.5

1115

lOA

15nH

150 x 10-3

1 X 10.9

lns

lOA

15nH

150

10.12

lps

lOA

15nH

150xl0-3

1 x 10.18

1Is

lOA

15nH

150 x 10-6

1x

Figure 11 illustrates the lead effect even more dramatically
for fast rising pulses ranging in rise time from milliseconds to
femtoseconds.

•• 1S,000,000V

".

w100,000 ~

>()

:::I

0

I

"2

e

".".
'.'.'.
1,SOOV
'...•.
lS0V

100 ~

lSV

10 ~

10.15

tR= 4ns

-

10. 13

I

~URRENT
WAVEFROM

FEMTO

dl

= - eL
dt

110~"

PICO

lA

../
'.

lOA

".

1.SV
tpEAK =2.SA, 300V

L

1"2 = 7.SnH

I

".

lS,OOOV

1,000~

~

V12ZAl

L '-v-'

'.'.'.
'."\.~ SO,OOOV

1,000,000 ~

j fa~

A

~
'-v-'

MODEL
1 0,000,000 ~

~ 10,000 ~

Vt-+-t-H-t-+-lH--H

e

1 x 10°

(.!l

r.

L

I

10.9

I

••••••••~:05

1~'7

NANO

I 1~·5

MICRO

I

10-3

I

MILU

TIME IN SECONDS

FIGURE 11. LEAD EFFECT OF 1 INCH CONNECTION (L ~ lSnH)

Temperature Coefficient (Electrical)
The temperature coefficient is usually of little importance. It
is most pronounced at low voltage and current levels and
decreases to practically zero at the upper end of the V-I
characteristics (Figure 12).

FIGURE 9. EXPONENTIAL PULSE APPLIED TO A RADIAL
DEVICE (SVlDIV., SOs/DIY)

IpEAK = 2.5A, 300V

!z
~

0
Ii: -0.1

it

V I-++-H-+-H-+-+-l

8

-0.2

~

1/

~

I

SAMPLE TYPE
V130LA10A

~ -0.31--+--+-+--+---ir--+--+--I
:::I

!;;: - 0 . 4 1 - - - - 1 - - + - - + - - + - - + - + - + - - 1
a:
w

-0.5 L - _ . L - _ . . L - _ . . L - _ . . L - _ - ' - _ - ' - _ - L _ - J
10.5
10'" 10-3 10.2 10.1 100
~
CURRENT (A)

~

FIGURE 10. EXPONENTIALPULSEAPPUEDTOA PIN-VARISTOR
(SVIDIV., SOns/DIV.)

FIGURE 12. TYPICAL TEMPERATURE COEFFICIENT OF VOLTAGE vs CURRENT (-SSOC to +12S0C)

12-34

Application Note 9307
Connector Pins vs Circuit Board
Suppressors
Circuit designers may ask, "Why use connector pin varistors
when suppressors could be located on the printed circuit
board of the electronic control module (ECM)?" Reasons
include saving space and avoiding side effects of circuit
board suppressor action.
A simplified schematic of an ECM is illustrated in Figure 13.
Suppressors usually would be installed across the power
analog and digital signal lines entering the ECM. These
would divert surges to ground to avoid upset or damage of
the ICs fed by those lines. However, side effects could occur
if the suppressors are located internally. The paths of circulating current for diverting surges to ground could be of significant length and impedance. If the suppressor current
paths share some impedance, then a surge current in one
suppressor could cause a surge voltage on the ground line
of another circuit. Also, surges can be coupled from one line
to another within the ECM by radiation or by capacitive
means. These problems are even more likely with surges
that have fast fronts causing high V = Ldlldt voltages, such
as when has tubes are activated.

DIGITAL

-+-....--1

ANALOG

-+-1-....--1

POWER

-I-t--<

a:LL
wo
a. ...

UlUl

ww

CJa:

a:o

The Transient Environment

=>w

The occurrence rate of surges varies over wide limits,
depending on the particular power system. These transients
are diflicult to deal with, due to their random occurrences
and the problems in defining their amplitude, duration and
energy content. Data collected from many independent
sources have led to the data shown In Figure 1. This prediction shows with certainty only a relative frequency of occurrence, while the absolute number of occurrences can be
described only in terms of low, medium or high exposure.
This data was taken from unprotected circuits with no surge
suppression devices.

ffi Ul

UlCJ

~~

10"1 f--+---+---''r-If---+!-~f---I

III

::;;
=>

z

10·2'----'--_ __L_.....J~_
0.3 0.5
2

__L'--.....JL.._~

5

10

20

SURGE CREST kV
'In Some Locations, Sparkover of Clearances May Limit the Overvoltages.

Copyright © Harris Corporation 1993

12-39

FIGURE 1. RATE OF SURGE OCCURENCES vs VOLTAGE
LEVEL AT UNPROTECTED LOCATIONS

Application Note 9308
be modeled to an oscillatory waveform (see Figure 2). A
surge impinging on the system excites the natural resonant
frequencies of the conductor system. As a result, not only
are the surges oscillatory but surges may have different
amplitudes and waveshapes at different locations in the system. These oscillatory frequencies range from 5kHz to
500kHz with 100kHz being a realistic choice.
In outdoor situations the surge waveforms recorded have
been categorized by virtue of the energy content associated
with them. These waveshapes involve greater energy than
those associated with the indoor environment. These
waveforms were found to be unidirectional in nature (see
Figure 3).

Transient Energy and Source Impedance
Some transients may be intentionally created in the circuit
due to inductive load switching, commutation voltage spikes,
etc. These transients are easy to suppress since their
energy content is known. It is the transients which are generated external to the circuit and coupled into it which cause
problems. These can be caused by the disCharge of electromagnetic energy, e.g., lightning or electrostatic discharge.
These transients are more difficult to identify, measure and
suppress. Regardless of their source, transients have one
thing in common - they are destructive. The destruction
potential of transients is defilned by their peak voltage, the
follow-on current and the time duration of the current flow,
that is:

0.9VPEAK

't

E
T = l0I'S (1= 100kHz)

= f Vc(l) -/(1) dt
o

where:

=

0.1 VPEAK

0.5I's~H-+---I----'!r---"c.~---

- - 60%OFVpEAK

FIGURE 2. O.Sms -100kHz RING WAVE (OPEN CIRCUIT VOLTAGE)
V
0.9 VpEAK'----'""".....- - - VPEAK

0.3 VPEAK

T, x 1.67 = 1.21'S

(a) OPEN-CIRCUIT WAVEFORM

E
Transient energy
I
Peak transient current
Vc = Resulting clamping voltage
= Time
t
't
= Impulse duration of the transient
It should be noted that considering the very small possibilities of a direct lightning hit it may be deemed economically
unfeasibie to protect against such transients. However, to
protect against transients generated by line switching, ESD,
EMP and other such causes is essential. and if ignored will
lead to expensive component and/or system losses.
The energy contained in a transient will be divided between
the transient suppressor and the line upon which it is travelling in a way which is determined by their two impedances. It
is essential to make a realistic assumption of the transient's
source impedance in order to ensure that the device
selected for protection has adequate surge handling capability. In a gas-tube arrestor, the low impedance of the arc after
sparkover forces most of the energy to be dissipated elsewhere - for instance in a power- follow current-limiting resistor that has to be added in series with the gap. This is one of
tile disadvantages of the gas-tube arrestor. A voltage clamping suppressor (e.g., a metal oxide varistor) must be capable
of absorbing a large amount of transient surge energy. Its
clamping action does not involve the power-follow energy
resulting from the short-circuit action of the gap.
The degree to which source impedance is important
depends largely on the type of suppressor used. The surge
suppressor must be able to handle the current passed
through them by the surge source. An assumption of too
high an impedlnoe (when testing the suppressor) may not
subject it to sufficient stresses, while the assumption of too
Iowan impedance may subject it to unrealistically large
stress; there is a trade off between the size/cost of the suppressor and the amount of protection required.

T2 x 1.25 = 81'S
(b) DISCHARGE CURRENT WAVEFORM
FIGURE 3. UNIDIRECTIONAL WAVESHAPES (OUTDOOR
LOCATIONS)

In a building, the source impedance and the load impedance
increases from the outside to locations well within the inside
of the building, i.e., as one gets further from the service

12-40

Application Note 9308
entrance, the impedance increases. Since the wire in a
structure does not provide much attention, the open circuit
voltages show little variation. Figure 4 illustrates the application of three categories to the wiring of a power system.
These three categories represent the majority of locations
from the electrical service entrance to the most remote wall
outlet. Table 1 is intended as an aid in the selection of surge
suppressors devices, since it is very difficult to select a specific value of source impedance.

Category A covers outlets and long branch circuits over 30
feet from category B and those over 60 feet from category C.
Category B is for major feeders and short branch circuits
from the electrical entrance. Examples at this location are
bus and feeder systems in industrial plants, distribution
panel devices, and lightning systems in commercial buildings. Category C applies to outdoor locations and the electrical service entrance. It covers the service drop from pole to
building entrance, the run between meter and the distribution
panel, the overhead line to detached buildings and underground lines to well pumps.

TABLE 1. SURGE VOLTAGES AND CURRENTS DEEMED TO REPRESENT THE INDOOR ENVIRONMENT AND RECOMMENDED
FOR USE IN DESIGNING PROTECTIVE SYSTEMS.
ENERGY (JOULES)
DEPOSITED IN A
SUPPRESSOR WITH
CLAMPING VOLTAGE

IMPULSE

LOCATION CATEGORY
CENTER

COMPARABLE
TOIEC
664 CATEGORY

MEDIUM
EXPOSURE
AMPLITUDE

WAVEFORM

TYPE OF SPECIMEN
OR LOAD CIRCUIT
CIRCUIT

SOOV

1000V

(120V Sys.) (240V Sys.)
A.

B.

Long branch circuits
and outlets

Major feeders short
branch circuits, and
load center

II

III

6kV

High Impedance (Note 1)

-

-

200A

Low Impedance (Note 2)

0.8

1.6

1.2/50J.lS

6kV

High Impedance (Note 1)

-

-

8/20~s

3kA

Low Impedance (Note 2)

40

80

0.5J.lS - 100kHz

6kV

High Impedance (Note 1)

O.SJ.lS - 100kHz

500A

Low Impedance

2

4

NOTES:
1. For high-impedance test specimens or load circuits, the voltage shown represents the surge voltage. In making simulation tests, use that
value for the open-circuit voltage of the test generator.
2. For low-impedance test specimens or load circuits, the current shown represents the discharge current of the surge (not the short-circuit
current of the power system). In making simulation tests, use that current for the short-circuit current of the test generator.
3. Other suppressors which have different clamping voltages would receive different energy levels.

z

o

~:3

01-

-0
~z
Il.

«
a:u.
wo
Q. ....

WAVEFORM

(/)(/)

ww

Cia:
a:o

The investigation into the indoor low voltage system revealed
that location Category A encounters transients with
oscillatory waveshapes with frequency ranges from 5kHz to
more than 500kHz; the 100kHz being deemed most
common (Figure 2). Surges recorded at the service
entrance, location Category B, are both oscillatory and
unidirectional in nature. The typical "lightning surge" has
been established as 1.2150~s voltage wave and 8120l-ls
current wave (Figure 3).

::>w
(/)(!l

u.a:
0::>
a:(/)

Ml

::;

6kV

1 0·11--+-_-+~r-+--*---'\f---I

::>

z

10.2 L-....._-'-_-'-~_...L!.._.....-4...J
0.3 0.5
1
2
5
10
20
SURGE CREST (kV)
'In Some Locations, Sparkover of Clearances May Limit the Overvoitages.

0.9 VPEAK

FIGURE 1. RATE OF SURGE OCCURRENCES vs VOLTAGE
LEVEL AT UNPROTECTED LOCATIONS
An area described as a "low exposure" area would have very
little lightning activity and few switching loads on the AC power
system. A "medium exposure" area is known for high lightning
activity, with frequent and severe switching transients. When
designing equipment for the global environment it is expedient
that it be, at least, deSigned for use in an area with "medium
exposure" transient occurrences. "High exposure" areas are
rare but real systems supplied by long overhead transmission
lines and subject to reflections at line ends, where the
characteristics of the installation produce high sparkover
levels of the clearances.

12-45

- - VPEAK

=

T 10J.lS (I

=100kHz)

0.1 VPEAK
0.5J.ls

-

60% OF VPEAK

FIGURE 2. O.511S -100kHz RING WAVE (OPEN CIRCUIT VOLTAGE)

Application Note 9310

v

Diverting the transient can be accomplished with a crowbar
type device or with a voltage clamping device. Crowbar
device types involve a switching action, either the breakdown
of a gas between electrodes or the turn on of a thyristor.
After switching on, they offer a very low impedance path
which diverts the transient away form the parallel-connected
load. Clamping devices have a varying impedance which
depends, either, on the current flowing through the device or
on the voltage across the terminals. These devices exhibit a
nonlinear impedance characteristic. The variation of the
impedance is monotonic; that is, it does not contain discontinuities in contrast to the crowbar device, which exhibits a
turn on action.

0.9 VpEAK

0.3 VPEAK

(a) OPEN-CIRCUIT WAVEFORM

Filters
The installation of a filter in series with the equipment seems
an obvious solution to overvoltage conditions. The
impedance of a low pass filter, e.g. a capacitor, forms a
voltage divider with the source impedance. As the frequency
components of a transient are several orders of magnitude
above the power frequency of the AC circuit, the inclusion of
the filter will result in attenuation of the transient at high
frequencies. Unfortunately, this simple approach may have
some undesirable side affects; a) unwanted resonances with
inductive components located elsewhere in the system
leading to high voltage peaks, b) high inrush currents during
switching and c) excessive reactive load on the power
system voltage. These undesirable effects can be reduced
by adding a series resistor, hence the popular use of RC
snubber networks. However, the price of the added
resistance is less effective clamping.

20~s

(b) DISCHARGE CURRENT WAVEFORM
FIGURE 3. UNIDIRECTIONAL WAVESHAPES (OUTDOOR
LOCATIONS)

Transient Protection
Once it has been decided to include transient suppression in
the design of equipment, the next stage in the process is to
decide on what protection technology to use and on how to
use it. The transient suppressor selected must be able to
suppress surges to levels which are below the failure threshold of the equipment being protected, and the suppressor
must survive a definite number of worst case transients.
When comparing the various devices available considerations must be given to characteristics such as protection
levels required, component survivability, cost, and size.
There are a number of different technologies available for
use as a transient suppressor in the low voltage AC mains
system. Generally speaking, these can be grouped into two
major categories of suppressors: a) those that attenuate
transients, thus preventing their propagation into the
sensitive circuit; and b) those that divert transients away
from sensitive loads and so limit the residual voltage.
Attenuating a transient - that is, keeping it from propagating
away from its source or keeping it from impinging on a sensitive load - is accomplished with by placing either filters or
isolating transformers in series within a circuit. The isolator
attenuates the transient (high frequency) and allows the
signal or power flow (low frequency) to continue undisturbed.

There is a fundamental limitation to the use of a filter for
transient suppression. Filter components have a response
which is a linear function of current. This is a big disadvantage in a situation where the source of the transient is
unknown and it is necessary to assume a source impedance
or an open-circuit voltage. If the assumption of the characteristics of the impinging transient are incorrect the
consequences for a linear suppressor is dramatic. A slight
change in the source impedance can result in a disproportionately increase in clamping voltage 6 .

Isolation Transformers
Isolation transformers generally consist of a primary and
secondary windings with an electrostatic shield between the
windings. The isolation transformer is placed between the
source and the equipment requiring protection. As its name
suggests, there is no conduction path between the primary
and secondary windings. A widely held belief is that
"isolation transformers attenuate voltage spikes" and "that
transients do not pass through the windings of the
transformer". When properly applied, the isolation transformers is useful to break ground loops, i. e. block common-mode
voltages.
Unfortunately, a simple isolation transformer provides no
differential-mode attenuation7 • Thus, a differential-mode
transient will be transmitted through the windings of the
device. Also, an isolation transformer will not provide any
voltage regulation.

12-46

Application Note 9310
Spark Gaps and Gas Tubes
Spark gap suppression is a crowbar suppression technology.
During an overvoltage condition, a crowbar device changes
from being an insulator to an almost ideal conductor. Crowbars suppress transients by brute force, (they have the effect
of dropping a metal crowbar across the system). The main
type of crowbar device is the gas tube surge arrester.
The original offering in the spark gap surge suppression
family was a carbon blocks. The carbon block suppressor
used the principle of a voltage arcing across an air gap. The
air gap breaks down at approximately 150V per thousands of
an inch. The minimum size gap was used to provide the
lowest level of protection without disturbing regular system
operation. When a transient overvoltage occurred in the
system, the air gap in the carbon block would ionize and
break down. The breakdown of the gap forms a very low
impedance path to ground thus diverting the surge away
from the equipment. As soon as the overvoltage condition
was removed, the air gap is restored and system operation
is continued.
The disadvantage of carbon block spark gap technology was
that short duration pulses "pitted" the surface of the carbon
blocks, thus removing small pieces of the face material. This
material builds up after a number of surges, eventually
causing a permanently shortened gap resulting in the need
for protector replacement. This had a very adverse effect on
the maintenance and replacement costs of the protection
circuit. Another disadvantage of this technology was the
difficulty in exactly controlling the breakdown characteristics
over a wide variety of operating conditions.
In an effort to overcome the disadvantages of the carbon
block, a sealed spark gap was developed which uses an
inert gas in a sealed ceramic envelope. This technology is
known as a gas tube surge arrester. In a non conducting
mode the impedance of the gas is in the gigiohms region.
The gas is set to ionize at a predetermined voltage and
offers an extremely low impedance path to ground. Once the
overvoltage condition is removed the gas deionizes and the
circuit restores itself to its normal operating condition.
The gas tube arrester is an inherently bidirectional device
and is comprised of either two or three electrodes lying
opposite each other in the sealed chamber. When the
voltage across the arrester terminals exceeds a certain limit,
known as the firing or breakdown voltage, it triggers an
electric arc. This arc limits the voltages applied to the
connected equipment. Gas tubes have typical DC firing
voltages between 150V and 1000V. They have the smallest
shunt resistance of all nonlinear transient suppressors,
typically in the milliohm range. Their capacitance is low,
between 1pF and 5pF, and they are commonly found in high
frequency transm iss ion applications, such as telephone
systems. Another advantage of this technology is its ability
to handle large currents (up to 20kA).
Gas tubes are transient duration dependent and do not
operate very successfully in a fast rising transient
environment. In the case of a l20V AC line, one would

expect to use a gas tube with a firing voltage of
approximately 200V DC. Under a transient condition of 100V
per microsecond, the actual firing voltage of the gas tube
turns out to be over 500V 5 . This slow response, resulting
from the finite time required for the gas to ionize, means that
a transient will be allowed to get through to the equipment.
Also, when faced with repeated surges, gas tubes tend to
wear out over time.
In applications where there is a normal operating voltage, as
in the AC mains, there is a possibility that the gas tube will
not reset itself once it has fired and suppressed the
transient. This condition is known as follow on current and is
defined by ANSI "as the current that passes through a device
from the connected power source following the passage of
discharge current". FollOW on current will maintain conduction of the ionized gas after the transient has disappeared
and the concern is that the follow on current may not clear
itself at a natural current zero and will result in a permanently
destroyed gas tube. In an AC mains application, it is not
sufficient to rely solely on the crossings of the sinusoidal
voltage to extinguish the follow current. If a gas tube is to be
used in this type of application, then a current limiting device
must be inserted in series between the gas tube and the
source of the follow current.

Silicon Avalanche Diodes
Although rarely used on AC mains application, due to their
very low transient surge capability, silicon avalanche diodes
are an excellent surge suppressor in low voltage DC applications. Avalanche diodes are deSigned with a wider junction
than a standard zener diode. This wide junction gives them a
greater ability than a zener to dissipate energy. Avalanche
diodes offer the tightest clamping voltage of available
devices. When a voltage greater than the device breakdown
is applied, the diode will conduct in the reverse direction.
A peak pulse power rating is usually given on diode
data sheets. Common values are 600W and 1500W. This
peak pulse power is the product of the maximum peak pulse
current, Ip~ and the maximum clamping voltage, Ve, at a
current of Ipp during a 10/1000~s transient duration. Use of
peak power ratings may be confusing when transients of
other than 10/1000~s are to be considered. A maximum
energy rating for non-repetitive, short duration transients,
similar to that supplied with MOVs, may be of more benefit to
design engineers.
The V-I characteristics are the best features of the avalanche
diode. Low voltage devices look extremely good. The
avalanche diodes has an excellent clamping voltage capability, but only over a small range of current (1 decade). The
biggest disadvantage to using the avalanche diode as a
transient suppressor on an AC mains line is its low peak
current handling capability. Due to their being, at most, only
two P-N junctions in a device their is very little material
available for the dissipation of the peak power generated
during high energy pulses.

12-47

Application Note 9310
Metal Oxide Varistor (MOV) 6
A metal oxide varistor (MOV) is a nonlinear device which has
the property of maintaining a relatively small voltage change
across its terminals while a disproportionately large surge
current flows through it. This nonlinear action allows the
MOV to divert the current of a surge when connected in parallel across a line and hold the voltage to a value that
protects the equipment connected to that line. Since the
voltage across the MOV is held at some level higher than the
normal line voltage while surge current flows, there is energy
deposited in the varistor during its surge diversion function.

its original value (Figure 4). To be conservative, peak pulse
limits have been established which, in many cases, have
been exceeded many fold without causing harm to the
device. Field studies and laboratory tests have shown that
the degradation which may result, after a number of pulses
outside the ratings of the device, is safe for the equipment
being protected. This does not mean that the established
limits should be ignored but rather viewed in the perspective
of the definition of a failed device. A failed device shows a ±
10% change in the nominal varistor voltage at the 1mA pOint.
This does not imply a non-protecting device, but rather a
device whose clamping voltage has been slightly altered.

The basic conduction mechanism of a MOV results from
semiconductor junctions (P-N junctions) at the boundaries of
the zinc oxide grains. A MOV is a multi junction device with
millions of grains acting as a series-parallel combination
between the electrical terminals. The voltage drop across a
single grain in nearly constant and is independent of grain
size.
The material of a metal oxide varistor is primarily zinc oxide
with small additions of bismuth, cobalt, manganese and
other metal oxides. The structure of the body consists of a
matrix of conductive zinc oxide grains separated by grain
boundaries, which provide the P-N junction semiconductor
characteristics. When the MOV is exposed to surges, the
zinc oxide exhibits a "bulk action" characteristic permitting it
to conduct large amounts of current without damage. The
bulk action is easily explained by imagining this material to
be made up of an array of semiconducting P-N junctions
arranged electrically in series and parallel so that the surge
is shared among all of the grains. Because of the finite
resistance of the grains, they act as current limiting resistors
and, consequently current flow is distributed throughout the
bulk of the material in a manner which reduces the current
concentration at each junction.
The MOV has many advantages which make it ideal for use
as a suppressor on the low voltage AC power line. The bulk
nature of its construction gives it the required energy
handling capability to handle the secondary level transients
resulting from indirect lightning hits.
MOVs are both cost and size effective, are widely available
and do not have a significant amount of overshoot. The
flexibility available in the manufacturing of these devices
means that different size varistors are available for transient
suppression in all categories of the ANSI/IEEE C62.41
standard. They have no follow on current and their response
time is more than sufficient for the types of transients
encountered in the AC mains environment.
One perceived disadvantage of a MOV is the degradation
which is perceived to be suffered by the varistor under a long
period of repetitive transient overvoltages. A common misconception is that the device is irreversibly damaged every
time it has to suppress a transient. This is not the case!
Under high energy transient conditions in excess of the
device ratings, the V-I characteristics of the varistor are seen
to change. This change is reflected in a decrease in the
nom inal varistor voltage. After applying a second or third
pulse the nominal varistor voltage can be seen to return to

45

«

~

40

"'-, ,

!<

'"
!:i

g

'-

l\.
.\.

~

..l.
\
35

Y

\

30

o

-

"

./

/

3

4

5

6

7

8

9

10

NUMBER OF PULSES

FIGURE 4. REPETITIVE PULSE WiTHSTAND CAPABILITIES

The avoidance of this form of failure mode is extremely
simple. Harris Semiconductor, the leading manufacturer of
varistors in this country, recommends that the way to ensure
the degradation failure mode is avoided is to follow the
simple rule; "Select the correct size of varistor". Time and
again it has been proven that this type of failure mode only
occurs when an incorrect sized/rated device is used.

Device Comparisons
A range of standard varistors, avalanche diodes, gas tube
arresters and filter capacitors were evaluated under a 6kV,
0.5(.ls x 100kHz ring wave. This transient replicates that
called out in location Category A of the ANSI/IEEE C62.41
and is the most benign condition expected in this location. All
of the selected devices are rated for use on a 120V AC line.
The results obtained from this evaluation are per Table 2.
TABLE 2. COMPARATIVE PERFORMANCE DATA8
DEVICE
PART
NUMBER

AVERAGE
PROTECTION
LEVEL (kV)

Metal Oxide
Varistor

V130LAI
V130LA5
V130LA10A

0.51

0/10

0.50

0/10

0.49

0/10

Silicon Avalanche
Diode

1.5KE200C

0.48

2110

Gas Tube Surge
Arrester

CG2-230

0.67

0/10

Filter Capacitor

C280AEA4K7

1.30

0/10

PROTECTION
TECHNOLOGY

12-48

FAILS!
SAMPLE
SIZE

Application Note 9310
The conclusions from this evaluation were: a) the silicon
avalanche diode had the lowest level of performance; b)
since location Category A is the location requiring the smallest sized suppressor, how can a device which does not
survive this testing be considered an adequate suppressor?
Not only does the avalanche diode fail, but it is also very
expensive when compared with an equivalently rated metal
oxide varistor. There are avalanche diodes available, in the
15kW family, which absorb large amounts of energy and it is
assumed that these devices will meet the transient requirements of this test. From a cost comparisons, these devices
are 15 - 20 times more expensive than an equivalent MOV.
This test further verifies that avalanche diodes become less
effective at higher voltages - that is as the voltage rating
increases their current capability decreases. Just the
opposite is true for the metal oxide varistor. To overcome the
avalanche diode's weaknesses, devices are connected in
series. In this situation its best feature - clamping voltage now becomes its downfall. Even with extremely close
matching of the VI characteristics, there can be large
differences in current distribution when the devices are
paralleled. Metal oxide varistors are not generally
recommended for parallel operation, since they must also be
matched, but the matching is to a lesser degree than in
diodes.
One of the primary requirements for a device rated for
suppression of transients on the AC mains is its ability to
handle large amounts of energy. In order for a device to have
a high energy handling capability, it requires a large amount
of bulk material with a high specific heat value in the
immediate vicinity of the P-N junctions. The primary material
in a metal oxide varistor is zinc oxide and the average grain
size for a MOV used in an AC application is 20 microns.
Observations over a range of compOSitional variations and
processing conditions show a fixed voltage drop of between
2V - 3V per grain with boundary junctions evenly distributed
along their edges. In the case of a 14mm varistor, part
number V130LA10A, which is commonly used in protection
of equipment in Category B locations, it would have an
approximate volume of 220mm 3 of material in the immediate
vicinity of the P-N grain junctions. An equivalent silicon
avalanche diode would have approximately 0.106mm 3 in
their Single P-N junction vicinity. Comparing the volume of
the varistor and the diode in the immediate vicinity of the
junction, the varistor has more than 2000 times a larger
mass available. Thus, the peak temperature in the bulk
material of the varistor per energy absorbed is much lower
than that for the single silicon avalanche diode junction. It is
the millions of P-N junctions, which are an integral part of the
MOV structure, that gives it excellent thermal and energy
handling properties.

Device Selection
After evaluating the advantages and disadvantages of the
various suppression technologies available, the device of
choice is clearly the metal oxide varistor. Once the decision
has been made as to which technology to use, it is now
necessary to decide on the actual device to select for a
particular application.
Metal oxide varistors have a wide variety of options available
in each voltage family. These offerings cover the large
number of different applications in the low voltage AC
environment, plus they address the different prevailing trains
of thought on the correct device to use. Device rating is
dependent on device size and within each voltage family are
a number of different rated parts. Common sizes of varistor
are 7, 10, 14, 20, 32, 40 and 60mm, with a number of
different package options also available in each size. This
advantage of the flexibility in the manufacturing of the MOV
also, unfortunately, tends to confuse the user as to how
select the correct device for a particular application.
To select the correct varistor for a specific application,
determine the following information:
1. The maximum system RMS voltage.
2. How is the MOV to be connected?
3. The MOV with a voltage 10% - 25% above system voltage.
4. The worst-case transient energy that will need to be
absorbed by the MOV. (Use the guidelines called out in
ANSI/IEEE C62.41 -1980).
5. The clamping voltage required for system protection (As
device size increases, for a given voltage family, the
clamping voltage gets better).

References
1. "ANSI/IEEE C62.41 -1980 Guide On Surge Voltages In
Low-Voltage AC Power Circuits"
2. "Voltage Transients and Their Suppression", Corbett, M.,
3. "Understanding AC Line Transient Immunity", Dash, G.
and Straus, I.,
4. "Suppression Of Voltage Transients Is An Art Trying To Be
A Science", GE # 660.33
5. "Surge Protection of Electronics", Haskell, Jr., N.H., P.E.
6. "Transient Voltage Suppression Devices", Harris Semiconductor DB450.2
7. "The Propagation and Attenuation of Surge Voltages and
Currents in Low Voltage AC Circuits", Martzloff, F.D., 1984
8. "Protective Level Comparison
Suppressors", Hopkins, D.C.

of

Voltage

Transient

9. "Comparison of Transient Suppressors!", Korn, S.

12-49

Harris Semiconductor
~-

No. AN9311.1

Harris MOVs

August 1993

THE ABCs OF MOVs
Author: Martin Corbett

The ABCs of MOVs
The material in this guide has been arranged in 3 parts for
easy reference; Section A, Section B and Section C.

"A" is for Applications

AC
VOLTAGE
(V)

ENERGY
(J)

This section provides general guidelines on what types of
MOV products are best suited for particular environments.

AC APPLICATIONS

B" is for Basics

130-1000

11-360

This section explains what Metal Oxide Varistors are, and
the basic function they perform.

"C" Is for Common Questions

Applications
To properly match the right MOV with a particular application, it is desirable to know:

3. The worst-case transient energy that will need to be absorbed by
the MOV.

LA Series

"C" III Series

70-250

Shock/Vibration
Environment
Quick Connect
Terminal

PA Series

130-275

11-23

Surface Mount

CH Series

130-750

2701050

High-Energy
Applications
Shock/Vibration
Environment

DASeries
HA Series
NASeries
DB Series

130-880

4503200

Primary Power Line
Protection

BASeries

1100-2800

380010000

Rigid Terminal for
Secure Wire
Contact

BB Series

1. The maximum system RMS or DC voltage.
2. The MOV voltage at 10 - 25% above maximum system voltage.

Through-Hole Board
Mounting
Low/Medium AC
Power Lines

PREFERRED
MOV
FAMILY

130-660

This section helps clarify important information about MOVs
for the design engineer, and answers questions that are
asked most often.
Want to know more? For a copy of the latest Harris MOV
data book, please contact your local Harris sales representative, or call 908-685-6000 and ask for Power/MOV Applications.

PACKAGING &
OTHER
CONSIDERATIONS

DC APPLICATIONS
4-460

0.1-35

Through-Hole Board
Mounting
Automotive Applications

ZA Series

10-115

08-10

Surface Mount

CH Series

9-431

0.06 1.70

Axial Leaded

MASeries

When the above information is available, these charts offer
basic application guidelines:

Copyright © Harris Corporation 1993

12-50

Application Note 9311
APPLICATION

(These include all BNBB, DNDB, LA and PA series
devices as well as ZA devices.) The epoxy encapsulant complies with UL flammability code UL94-VO.
Under UL Standard 497B, all ZA and LA series
devices are UL approved to file number E135010.
Many HarriS MOVs are CSA- approved, including LA
and PA series types. Check the latest copy of the Harris MOV data book for complete, up-te-date approvals.

PREFERRED MOV
FAMILY

TVNCRIWhite Goods

ZA, LA, ·C" III, CH and MA
Series

Motor Control

ZA, LA, ·C"III, PA, HA, NA,
BA, BB, DA and DB Series

Transformer (Primary Protection)

ZA, LA, ·C"III, PA, BA, BB,
DA, DB, HA and NA Series

Automotive Environment

Instrumentation

MA, ZA and CH Series

Q.

Automotive (Primary/Secondary
Protection)

ZA and CH Series

How can a radial MOV meet the automotive requirements for temperature cycle and 125°C operating temperatures?

Noise Suppression

MA, CH, ZA and LA, ·C· III
Series

A.

Power Supply

PA, LA, ·C· III, ZA, HA, NA,
BA, BB, DA and DB Series

On request. Harris MOVs can be coated with a special
phenolic material that withstands these harsh conditions. Special part number designations will be
assigned.

Transient Voltage Suppressor
Strip

LA, ·C"III, HA and NA
Series

Connecting MOVs for Added Protection
Q.

Can MOVs be connected in parallel?

A.

Yes. The paralleling of MOVs provides increased peak
current and energy-handling capabilities for a given
application. The determination of which MOVs to use
is a critical one in order to ensure that uniform current
sharing occurs at high transient levels. It is recommended that Harris performs this screening and selection process.

Q.

Can MOVs be connected in series to provide greater
protection?

A.

Yes. MOVs can be connected in series to provide voltage ratings higher than those normally available, or to
provide ratings between the standard offerings.

Q.

How are MOVs connected for single-phase and threephase protection?

A.

FOR SINGLE-PHASE AC: The optimum protection is
to connect evenly rated MOVs from hot-neutral, hotground and neutral-ground. If this configuration is not
poSSible, connection between hot-neutral and hotground is best.
FOR THREE-PHASE AC: Please refer to the Harris
MOV data book.

Basics
What Is a Harris MOV?
A Harris MOV is a Metal Oxide Varistor. Varistors are voltage
dependent, nonlinear devices which have an electrical behavior
similar to back-te-back zener diodes. The varistor's symmetrical, sharp breakdown characteristics enable it to provide excellent transient suppression performance. When exposed to high
voltage transients, the varistor impedance changes many
orders of magnitude from a near open circuit to a highly conductive level and clamps the transient voltage to a safe level.
The potentially destructive energy of the incoming transient
pulse is absorbed by the varistor, thereby protecting vulnerable
circuit components and preventing potentially costly system
damage.
What Is a Harris MOV Made Of?
The Harris varistor is composed primarily of zinc oxide with
small additions of bismuth, cobalt, manganese and other
metal oxides. The structure of the body consists of a matrix
of conductive zinc oJ(ide grains separated by grain boundaries which provide P-N junction semiconductor characteristics.
What Is the Scope of the Harris MOV Product Line?
Standard Harris varistors are available with AC operating
voltages from 4V to 3200V. Higher voltages are limited only
by packaging ability. Peak current handling exceeds 70,000
amps, and energy capability extends beyond 10,000 joules
for the larger units. Package styles include the tiny tubular
device used in connectors, and progress in size up to the
rugged industrial blocks.

Common Questions

Current, Steering or Directing
Q.

Does an MOV simply steer current?

A.

No. It is incorrect to believe that an MOV device merely
re-directs energy. In fact, the MOV dissipates heat
energy within the device by actually absorbing this
energy. The degree or level to which this absorption
can take place is dependent on the energy rating of
the device.

Date Codes
Q.

Can you explain the date codes on a Harris MOV?

A.

The date code tells you when the device was manufactured. It consists of a letter (which represents the
month) followed by a number (which represents the
year). Here is the code: A January, C February, E
March, G April, J May, L June, N July, P
August, S September, U October, W November,

Approvals
Q.

Are MOVs subject to UL listing or CSA approval?

A.

Yes. All Harris MOVs rated at 1 30VRMS or higher are
UL-listed under file number E75961 andlor E56529.

12-51

=

=
=

=

=

=

=

=

=
=

=

Application Note 9311

=

=

=

=

Y December; 9 1989, 0 = 1990,1 1991,2 1992.
For example: Using this system, a date code of "A1"
tells you the product was manufactured in January
1991.

number indicates either a) the maximum AC(RMS) continuous voltage the device can handle. or b) the nominal DC voltage (measured with almA test current
through the varistor).
Letter .... These two letters (LA, DB, PA, etc.) correspond to a specific product series and package configuration.

Failure of Device and Fuse Selection
Q.

How does an MOV fail?

A.

An MOV is designed to fail as a short circuit. If applied
conditions significantly exceed the energy rating of the
device, the MOV may be completely destroyed. For
this reason, the use of current-limiting fuses is suggested.

Number ... This
energy rating.

number

represents

the

relative

Letter .... This final letter indicates the voltage selection of the device.

Q.

How do you select a fuse to prevent failure of an
MOV?

Q.

Why isn't the entire part number branded on the
device?

A.

Fuses should be chosen to limit current below the level
where damage to the MOV package could occur. Specific guidance is provided in the Harris MOV data
book. Generally, the fuse should be placed in series
with either the varistor or the line.

A.

The small size of some components cannot accommodate the relatively lengthy part number. Consequently,
abbreviated brands are used. The Harris MOV data
book lists these abbreviated brands (along with their
corresponding factory part numbers) in the device ratings and characteristics tables of each series.

Heavy Metals
Q.

A.

Are heavy metals such as cadmium or mercury used
in the manufacture of Harris MOVs?
No. There are no heavy metals used in the manufaclure of Harris MOVs.

Lead Inductance/Lead Forms/Lead Coating

Sensitivity
Q.

Are MOVs sensitive to polarity?

A.

No. MOVs can be used in a bi-directional mode, and
provide equal protection in both directions.

Q.

Are MOVs sensitive to electrostatic discharge?
No. In fact, MOVs are specifically designed to protect
sensitive integrated circuits from ESD spikes.

Q.

Does lead inductance/capacitance affect MOV performance?

A.

A.

Yes. Transient wave forms with steep fronts (:51!lS) and
in excess of several amps produce an increase in voltage across the varistor. This phenomenon, a characteristicof all leaded devices including zeners, is known
as overshoot. Unlike zeners, however. MOVs are available without leads. Our CH and CPV/CS series, for
example, consist of lead less components which do not
exhibit overshoot.

Q.

Generally speaking, are MOVs sensitive to chemicaV
pressure when potted?

A.

No.

Q.

What standard lead forms are available an Harris
radial MOVs?

A.

Radial lead types include outcrimp, undercrimp and
inline configurations. This broad offering helps meet
several criteria for circuit board components (e.g.,
mechanical stability, lead length and solder ability).
Harris radial MOVs are also available in tape-and-reel
packaging to accommodate auto-insertion equipment.

Q.

Are MOV leads coated or tinned?

A.

Yes. All leads are electroplated to provide a uniform
surface. This process ensures that a subsequent solder coat may be evenly applied.

Part Numbering
Q.

What information does an MOV part number provide?

A.

MOV part numbers were created to impart product
data. Each designation follows the pattern:
LETTERlNUMBERlLETTERINUMBERlLETTER.

Speed of Response, Compared to Zeners
Q.

Are zeners significantly faster than MOVs?

A.

No, not to the extent of the claims made by many
zener manufacturers. The intrinsic response time of
MOV material is 500 picoseconds. As the vast majority
of transients have a slower rise time than this, it is of
little or no significance to compare speeds of
response. The response time of a leaded MOV or
zener is affected by circuit configuration and lead
inductance.

Voltage Regulation, Voltage Limits
Q.

Can an MOV be used as a voltage regulator?

A.

No. MOVs function as nonlinear impedance devices.
They are exceptional at dissipating transient voltage
spikes, but they cannot dissipate continuous low level
power.

Q.

Is it possible to get MOVs with voltages other than
those listed in the data book?

A.

Yes. The Harris MOV data book discusses standard
voltages only. Application-specific MOVs with voltages
tailored to customer requirements can be manufactured upon request. Contact your Harris sales representative to discuss your individual needs.

Letter. . . . The prefix "V" stands for Varistor.
Number .. Depending on the product family. this

12-52

Harris Semiconductor

No. AN9312.1

-

Harris MOVs

August 1993

SUPPRESSION OF TRANSIENTS IN AN
AUTOMOTIVE ENVIRONMENT
Author: Martin Corbett

Introduction
Market surveys have shown that, while the automotive market is growing about 2% a year in terms of new cars, the
actual content of electronics in the car is growing much
faster. The initial stage of the introduction of electronics into
the automobile began with discrete power devices and IC
components. These were to be found in the alternator rectifier, the electronic ignition system and the voltage regulator.
This was followed by digital ICs and microprocessors, which
are common in engine controls and trip computers. As semiconductor capability continues to expand, the usage of
smart power devices and massive memories will become
common. The benefits of this smart power will be found in
improved electronic controls and shared visual displays. To
completely benefit from these advances, protection from
transient overvoltages must be supplied.

Transient Environment
As the control circuitry in the automobile continues to
develop, there is a greater need to consider the capability of
new technology in terms of survivability to the commonly
encountered transients in the automotive environment. The
circuit designer must ensure reliable circuit operation in this
severe transient environment. The transients on the automobile power supply range form the severe, high energy,
transients generated by the alternator/regulator system to
the low-level "noise" generated by the ignition system and
various accessories. A standard automotive electrical
system has all of these elements necessary to generate
undesirable transients (Figure 1).

Unlike other transient environments where external
influences have the greatest impact, the transient environment of the automobile is one of the best understood. The
severest transients result from either a load dump condition
or a jump start overvoltage condition. Other transients may
also result from relays and solenoids switching on and off,
and from fuses opening.
Load Dump

The load dump overvoltage is the most formidable transient
encountered in the automotive environment. It is an exponentially decaying positive voltage which occurs in the event
of a battery disconnect while the alternator is still generating
charging current with other loads remaining on the alternator
circuit at the time of battery disconnect. The load dump
amplitude depends on the alternator speed and the level of
the alternator field excitation at the moment of battery
disconnection. A load dump may result from a battery disconnect resulting from cable corrosion, poor connection or
an intentional battery disconnect while the car is still running.
Independent studies by the Society of Automotive Engineers
(SAE) have shown that voltage spikes from 25V to 125V can
easily be generated 1, and they may last anywhere from
40ms to 400ms. The internal resistance of an alternator is
mainly a function of the alternator rotational speed and
excitation current. This resistance is typically between 0.50
and 40 (Figure 2).

v

Vs

Vs = 25 10 125V
VB = 14V
T = 40 10 400ms

REVERSE
BATTERY

FIGURE 1. TYPICAL AUTOMOTIVE TRANSIENTS

T, =510 1Oms
R =0.5 to 4 ohms

FIGURE 2. LOAD DUMP TRANSIENT

Copyright © Harris Corporation 1993

12-53

Application Note 9312
Jump Start
The jump start transient results from the temporary application of an overvoltage in excess of the rated battery voltage.
The circuit power supply may be subjected to a temporary
overvoltage condition due to the voltage regulator failing or it
may be deliberately generated when it becomes necessary
to boost start the car. Unfortunately, under such an
application, the majority of repair vehicles use 24V "battery"
jump to start the car. Automotive specifications call out an
extreme condition of jump start overvoltage application of
up to 5 minutes.
The Society of Automotive Engineers(SAE) has defined the
automotive power supply transients which are present in the
system.
Table 1 shows some sources, amplitudes, polarity, and
energy levels of the generated transients found in the
automotive electrical system 2 .

ENERGY
CAPABILITY
CAUSE

Steady State Failed voltage
regulator

VOLTAGE
AMPLITUDE

.
.

FREQUENCY
OF OCCURRENCE
Infrequent

Jump starts with
24V battery

Infrequent

±24V
200msto
400ms

< 320).ls

200ms

Load dump;
disconnection of
battery while at
high charging
Inductive-load
switching
transient
Alternator field
decay

> lOJ

Infrequent

< 125V
< 1J

As previously mentioned, the maximum load dump energy
available to the central suppressor depends on a combination of the alternator size and the loads that share the surge
current and energy which are thus generated. It must be
remembered that there are many different automotive
electronic configurations which result in a variety of diverse
load dumps.

Often

300Vto +80V
< 1J

Each Turn-Off

-1 OOV to -40V
90ms

1ms

Ignition pulse,
battery disconnected

<0.5J

Mutual coupling
in harness

< 1J

<75V

Multilayer
(AUML)4,5

< 500Hz
Several
Times in
Vehicle Life

Ignition pulse,
normal

< O.OOlJ

Transient

Voltage

Surge

Suppressor

The new automotive multilayer (AUML) transient voltage
suppressor is a voltage dependent, nonlinear device. It has
an electrical behavior similar to that of a back-ta-back zener
diodes and it is inherently bidirectional. It offers protection
from transients in both the forward and reverse directions.
When exposed to high voltage transients, the AUML undergoes a nonlinear impedance chan~e which is many orders of
magnitude, from approximately 10 to 10n

Often

<200V
15J.lS

The sensitive electronics of the automobile need to be
protected from both repetitive and random transients. In an
environment of random transients, the dominating
constraints are energy and clamping voltage vs standby
power dissipation. For repetitive transients, transient power
dissipation places an additional constraint on the choice of
suppression device.

A centrally located suppressor is the principal transient
suppression device used in most automobiles. It is
connected directly across the main power supply line without
any intervening load resistance. It must be capable of
absorbing the entire available load dump energy, and must
also withstand the full jump start voltage. To be cost
effective, it is usually located in the most critical electronic
module. Additional secondary suppression is also employed
at other locations in the system for further suppression and
to control locally generated transients.

+18V
5 minutes

Suppressor Applicationsa

It must also be noted that the worst case transient scenarios,
load dump and jump start, place conflicting constraints on
the automotive suppressor. The high energy content of the
load dump transient must be clamped to a worst case voltage of 40V, while the leakage current/power dissipation
drawn under a jump start condition must also be kept to a
minimum.

TABLE 1. TYPICAL AUTOMOTIVE TRANSIENTS

LENGTH OF
TRANSIENT

The achievement of maximum transient protection involves
many factors. First, consequences of a failure should be
determined. Current limiting impedances and noise immunities need to be considered. The state of the circuit under
transient conditions (on, off, unknown) and the availability of
low cost components capable of withstanding the transients
are other factors. Furthermore, the interaction of other parts
of the automotive electrical system with the circuit under
transient conditions may require definition.

< 500Hz
Continuous

3V
Accessory noise

< 1.5V

50Hz to 10kHz

Transceiver
feedback

~20mV

R.F.

The crystalline structure of the AUML transient voltage
suppressor consists of a matrix of fine, conductive grains
separated by uniform grain boundaries, forming P-N
junctions (Figure 3). These boundaries are responsible for
blocking conduction at low voltages, and are the source of

12-54

Application Note 9312
the nonlinear electrical conduction at higher voltages.
Conduction of the transient energy takes place between the
millions of P-N junctions present in the device. The uniform
crystalline grains act as heat sinks for the energy absorbed
by the device under a transient condition, and ensures an
even distribution of the transient energy (heat) throughout
the device. This even distribution results in enhanced
transient energy capability and long term reliability.

0.100 inches), "1812" (0.180 x 0.120 inches) and "2220"
(0.220 x 0.200 inches). The correct device to use depends
on the location of the suppressor in the overall electronics
system.

Device Ratings and Characteristics
Package Outline
The present size offerings of the AUML series are the industry 2220, 1812 and 1210 standard form factors. Since the
AUML device is inherently bidirectional, symmetrical orientation for placement on a printed circu it board is not a concern.
Its robust construction makes it ideally suitable to endure the
thermal stresses involved in the soldering, assembling and
manufacturing steps involved in surface mount technology.
The AUML device is inherently paSSivated by means of the
fired ceramic material. They will not support combustion and
are thus immune to the risk of flammability which may be
present in the plastiC or epoxy molded diode devices.

FIRED CERAMIC

Load Dump Energy Capability
The most damaging classification of transients an automobile must survive is a load dump discharge occurrence. A
load dump transient occurs when the alternator load in the
automobile is abruptly reduced and the battery clamping
effect is thus removed. The worst case scenario of the load
dump occurs when the battery is disconnected while
operating at full rated load. The resultant load dump energy
handling capability serves as an excellent figure of merit for
the AUML suppressor.

FIGURE 3. AUML TRANSIENT VOLTAGE SUPPRESSOR

The AUML is constructed by forming a combination of alternating electrode layers and semiconducting ceramic layers
into a rectangular block. Each alternate layer of electrode
material, separated by ceramic semiconducting material, is
connected to opposite end terminations of the device.
SEMICONDUCTING
CERAMIC

INN~ER~II~~~~~~~~~

"''''''''~,

END
TERMINATION

FIGURE 4. AUML INNER CONSTRUCTION

The paralleled arrangement of the inner electrode layers
represents significantly more active surface area than the
small outline of the package may suggest (Figure 4). This
increased active surface area, combined with an interdigitated block formation, results in proportionally higher peak
energy capability.
The AUML surge suppressor is a surface mountable device
that is much smaller in size than the components it is
designed to protect. The present size offerings for suppression in the automotive environment are "1210" (0.120 x

Standard load dump specifications require a device capability of 10 pulses at rated energy, across a temperature range
of -40°C to + 125°C. This capability requirement is well within
the ratings of all of the AU ML series.
Due to the assortment of electronic applications in an
automotive circuit, there is a need for a wide range of surge
suppressors. The transient environment can generally be
divided into three distinct sections and there will be a need
for a different type of suppressor within each section. The
2220 size was designed for operation in the primary
transient area, i.e. directly across the alternator. The 1812
size for secondary protection and the 1210 size for tertiary
protection. A typically load dump transient results in an
energy discharge of approximately 100J (depending on the
size of the alternator). The deciding factor in the selection of
the correct size suppressor is the amount of energy which is
dissipated in the series and parallel loads in the circuit. The
higher the impedance between the battery and the system
requiring suppression, the smaller is the suppressor
required.
Random samples of the 1210, 1812 and 2220 devices were
subjected to repetitive load dump pulses at their rated
energy level. This testing was performed across a temperature spectrum from -40°C to +125 0 C. This temperature
range simulates both passenger compartment and under the
hood operation. There was virtually no change in the device
characteristics of any of the units tested (Figure 5).

12-55

z

o

!;i[fl
01-

-0
~z

c..



w

a..
:;
w

I-

The liquids used in this process are relatively expensive and
so, to overcome this a secondary less expensive solvent is
often used. This solvent has a boiling temperature below
50°C. Assemblies are passed through the secondary vapor
and into the primary vapor. The rate of flow through the
vapors is determined by the mass of the substrate. As in the
case of all soldering operations, the time the components sit
at the peak temperature should be kept to a minimum. In the
case of Harris surface mount suppressors a dwell of no more
than 10 seconds at 222"C is recommended.
On emergence from the solder system, cooling to ambient
should be allowed to occur naturally. Natural cooling allows a
gradual relaxation of thermal mismatch stresses in the
solder joints. Forced air cooling should be avoided as it can
induce thermal breakage.

Q 140

'to.

Ie
II:

contact with the CQlder parts of the substrate and then
condenses. In this process all cold areas are heated evenly
and no areas can be heated higher than the boiling point of
the solvent, thus preventing charring of the flux. This method
gives a very rapid and even heating affect. Further
advantages of vapor phase soldering is the excellent control
of temperature and that the soldering operation is performed
in an inert atmosphere.

The recommended temperature profile for the vapor phase
soldering process is as Figure 13 and Table 6.

80
60
40

225

20

200
_

220C

175

U

0
2

. 3

4

5

II:

:::> 125

IeII:

FIGURE 12. TYPICAL TEMPERATURE PROFILE FOR IR REFLOW SOLDER PROCESS

w
a.. 100
::Ii
w

I-

77

TABLE 5. RECOMMENDED TEMPERATURE PROFILE

50

INFRARED REFLOW

25

TEMPERATURE (OC)

TIME (SECONDS)

25-60

60

60-120

60

120-155

30

155-155

60

155-220

60

220-220

10

220-50

NATURAL
COOLING

;- 150

6

TIME (MINUTES)

5

10

15

20 25
30 35
TIME (SECONDS)

40

45

50

FIGURE 13. TYPICAL TEMPERATURE PROFILE FOR VAPOR
PHASE REFLOW SOLDERING
TABLE 6. RECOMMENDED TEMPERATURE PROFILE
INFRARED REFLOW
TEMPERATURE rC)

60

Vapor Phase Reflow
Vapor phase reflow soldering involves exposing the assembly and joints to be soldered to a vapor atmosphere of an
inert heated solvent. The solvent is vaporized by heating
coils or a molten alloy, in the sump or bath. Heat is released
and transferred to the assembly where the vapor comes in

12-60

TIME (SECONDS)

25-90

8

90-150

13

150-222

3

222-222

10

222-80

7

80-25

10

Application Note 9312
Wave Solder

Cleaning Methods and Cleaning Aulds

This technique, while primarily used for soldering thru hole
or leaded devices inserted into printed circuit boards, has
also been successfully adapted to accommodate a hybrid
technology where leaded, inserted components and
adhesive bonded surface mount components populate the
same circuit board.

The objective of the cleaning process is to remove any
contamination, from the board, which may affect the
chemical, physical or electrical performance of the circuit in
its working environment.

The components to be soldered are first bonded to the
substrate by means of a temporary adhesive. The board is
then fluxed, preheated and dipped or dragged through two
waves of solder. The preheating stage serves many
functions. It evaporates most of the flux solvent, increases
the activity of the flux and accelerates the solder wetting. It
also reduces the magnitude of the temperature change
experienced by the substrate and components.
The first wave in the solder process is a high velocity turbulent wave that deposits large quantities of solder on all
wettable surfaces it contacts. This turbulent wave is aimed at
solving one of the two problems inherent in wave soldering
surface mount components, a defect called voiding (i.e.
skipped areas). One disadvantage of the high velocity turbulent wave is that it gives rise to a second defect known as
bridging, where the excess solder thrown at the board by the
turbulent wave spans between adjacent pads or circuit
elements thus creating unwanted interconnects and shorts.
The second, smooth wave accomplishes a clean up
operation, melting and removing any bridges created by the
turbulent wave. The smooth wave also subjects all previous
soldered and wetted surfaces to a sufficiently high temperature to ensure good solder bonding to the circuit and
component metallizations. In wave soldering, it is important
that the solder have low surface tension to improve its
surface wetting characteristics. Therefore, the molten solder
bath is maintained at temperatures above its liquid pOint.
On emergence from the solder wave, cooling to ambient
should be allowed to occur naturally. Natural cooling allows a
gradual relaxation of thermal mismatch stresses in the
solder jOints. Forced air cooling should be avoided as it can
induce thermal breakage.
The recommended temperature profile for the wave soldering process is as Table 7.
TABLE 7. RECOMMENDED TEMPERATURE PROFILE
WAVE SOLDER
TEMPERATURE (GC)

TIME (SECONDS)

25-125

60

125-180

60

180-260

60

260-260

5

260-180

60

180-80

60

80-25

60

There are a wide variety of cleaning processes which can be
used, including aqueous based, solvent based or a mixture
of both, tailored to meet specific applications. After the soldering of surface mount components there is less residue to
remove than in conventional through hole soldering. The
cleaning process selected must be capable of removing any
contaminants from beneath the surface mount assemblies.
Optimum cleaning is achieved by avoiding undue delays
between the cleaning and soldering operations; by a
minimum substrate to component clearance of O.15mm and
by avoiding the high temperatures at which oxidation occurs.
Harris recommends 1,1,1 trichloroethane solvent in an
ultrasonic bath, with a cleaning time of between two and five
minutes. Other solvents which may be better suited to a
particular application and can also be used may include
those outlined in Table 8.
TABLE 8. CLEANING FLUIDS
Water

Acetone

Isopropyl Alcohol

Fluorocarbon 113

Fluorocarbon 113 Alcohol

N-Butyl

1,1,1, Trichloroethane

Trichloroethane

Toluene

Methane

Comparison to Other Device
Technologies
There are many design considerations involved when
selecting the correct transient suppressor for an automotive
application. One obvious consideration is cost. Other factors
such as load dump energy capability, clamping voltage,
temperature dependance, and size must also be weighed.
Each of these factors will now be discussed.
Energy Capability
The large active electrode area available to the AUML
suppressor ensures that load dump energy handling capability is one of it's best features. By virtue of its interdigitated
construction, the AUML suppressor is capable of dissipating
significant amounts of energy over a very small volume of
material. The interdigitated construction also ensures that
the very high temperatures resulting from a load dump
transient will be evenly dissipated through millions of P-N
junctions.
Silicon surge suppressors may also be used for the suppression of transients in an automotive environment. In the case
of a silicon suppressor, only one P-N junction is available to
handle the energy of the load transient. It should be noted
that many different materials, with varying thermal coefficients of expansion, are employed in the construction of a

12-61

Application Note 9312
silicon suppressor. This may result in extreme thermal
stresses being created in the body of the suppressor during
a load dump condition. In an attempt to overcome this
weakness, a number of silicon die are placed in series in a
sandwich construction, with a metal header to act as a heat
sink and solder pellets for bonding (Figure 14).

~ SOLDER

~ HEADER

t3I

PELLET

I

Clamping Voltage
In the majority of automotive applications, the maximum
clamping voltage requirement for the primary surge suppressor is 40V at 40A (8/20~s current waveform). Both the AUML
and silicon suppressors easily meet this requirement.
The V-I characteristic for a silicon diode is defined over a
small current range (1 decade). The AUML current range is
extended over a few more decades, which illustrates it's
large peak current and energy handling capability.

SIUCON
DIE

Temperature Effects
Both the AUML and the silicon diode have a temperature
dependance with respect to off state leakage current - leakage current increases as temperature increases. However,
beyond the breakdown point, the clamping voltage of the
AUML will remain constant between +25 0 C and +125 0 C
while the clamping voltage for the zener diode at +125 0 C i~
higher than that specified at +25 0 C.
FIGURE 14. TYPICAL INTERNAL CONSTRUCTION OF A
SILICON SUPPRESSOR

Size

This construction is designed to distribute the transient
energy through more than one P-N junction, and somewhat
helps to alleviate the steep temperature build up during the
transient. Even with this metal sandwich, the silicon suppressor is not completely effective in handling transient pulses.
This is because of the thermal time constant involved in
transporting the energy (heat) from where it is generated
(the silicon die) to the metal heat sink.

Up to now, the only surface mounted surge suppressors
available are leaded gull-wing and j-bend silicon diodes or a
relatively large surface mount metal oxide varistor. In both of
these cases a large area of the PC board is needed for
mount down. As previously mentioned, electrically equivalent AUML suppressors are as much as three to four times
as small than their silicon counterparts, resulting in significant surface mount PC board area savings (Figure 16).

Even though high energy load dump transients are much
less frequent than low energy ones, it takes only one such
transient to completely damage the transient suppressor and
hence the component or circuit being protected.
Comparing the typical peak current, energy and power
derating curves of the Harris multilayer to an equivalent
silicon suppressor at +125 0 C, the AUML has 100% of rated
value while the zener diode has only 35% (Figure 15).

TOSHIBA DIODE 1.5A5A21
or

~

L2.09~+

MOTOROLA DIODE MR25251

tt

0.241

1

T-:;;---.i
0.563Mo.113

..:JrI-O.660-j"1"
0.118
HARRIS AUML2220

100+-_--.....,

U)

HARRIS
MULTI-LAYER

75

CI

z

~

SIUCON
SUPPRESSOR

a: 50

,.

IL

0

25

o

50

100
150
200
TEMPERATURE ("C)

FIGURE 16. SIZE COMPARISONS OF AUTOMOTIVE SURGE
SUPPRESSORS
The compact size of the AUML suppressor is obtained by the
paralleled stacking manufacturing process. This results in a
high density energy absorber where the device volume is not
taken up by lead frames, headers, external leads, and epoxy.
Additional board area savings are also realized with the
smaller solder mounting area required by the AUML.

250

FIGURE 15. AUML AND SILICON SUPPRESSORS CURRENT,
ENERGY AND POWER DERATING CURVE

12-62

Application Note 9312
Description of AUML Ratings and
Characteristics
Maximum Continuous DC Working Voltage (VM(DC): This
is the maximum continuous dc voltage which may be
applied, up to the maximum operating temperature
(+125'C), to the AUML suppressor. This voltage is used as
the reference test point for leakage current and is always
less than the breakdown voltage of the device.
Load Dump Energy Rating (Wid): A load dump occurs
when the alternator load is suddenly reduced. The worst
case load dump is caused by disconnecting a discharged
battery when the alternator is running at full load. The load
dump energy discharge occurs with the rated battery voltage
also applied and must not cause device failure. This pulse
can be applied to the AUML suppressor in either polarity.
Maximum Clamping Voltage (Vel: This is the peak voltage
appearing across the AUML suppressor when measured
with an 8120I1S pulse current (Figure 17).

Nominal Voltage (VN(DC»: This is the voltage at which the
AUML enters its conduction state and begins to suppress
transients. In the automotive environment this voltage is
defined at the 10 milliamp point and has a minimum and
maximum voltage specified.

References
(1) Electromagnetic Susceptibility Measurement Procedures for Vehicle Components - SAE J1113 Aug 1987.
(2) Harris Semiconductor Application Note AN9002.
(3) Transient Voltage Suppression Devices, Harris Semiconductor DB450.2 .

...

~

Leakage Current (Ill: This is the amount of current drawn
by the AUML suppressor in its non-operational mode, i.e.
when the voltage applied across the AUML does not exceed
the rated VM(DC) voltage of the device.

100

1---1:-...

(4) "Transient Suppression in the Automotive Environment",
Corbett, M. and McCambridge, P., Automotive Electronic
Design 10/91.

~ 90
(.)

~

W

A.

~

50

I--H-+--~

(5) Harris Semiconductor Application Note AN9108.
(6) CANE SMT 2588, Syfer Technology Limited, UK.

!Zw
(.)

II:

-+________-=::==~

~ 10L-~~~____

01'" - T1 - FRONT TIME
- U TIME TO HALF VALUE

20~s

z
o
~ffi
Of-

-0
~z
Q.

c:(

12-63

13
HIGH RELIABILITY SERIES MECHANICAL AND
ENVIRONMENTAL TESTING FOR AEROSPACE, MILITARY, AND
HIGH RELIABILITY APPLICATIONS
The high-reliability Harris varistor is the latest step in increased product performance, and is available for applications requiring
quality and reliability assurance levels consistent with military or other standards. (Mil-Std-19500, Mil-S-750, Method 202)
This series of high-reliability varistors involves five categories:
13.1

DESC Qualified Parts List (QPL) Mil-R-83536.
4 types pre senti y available.

13.2

DESC Source Control Drawings based on Mil-R-83530.
83 types presently available:
ZA Series - Drawing #87063
DB Series - Drawing #90065
PA Series - Drawing #88063

13.3

Harris high reliability series offers TX equivalents.
29 types presently available.

13.4

Custom types processed to customer-specific requirements - (SCD) or to standard military flow.

13.5

Radiation hardened varistors.

Credentials
Harris varistors and quality management systems are:
-

DESC approved
QPLlisted
CECC approved
ISO approved
UL approved
CSA approved.

13-1

13.1 DESC QUALIFIED PARTS LIST (QPL) MIL-R-83530
Table 13.1. MIL-R-835301l Ratings and Characteristics
VOLTAGE
RATING
(V)
NOMINAL
PART
VARISTOR
ENERGY
NUMBER VOLTAGE TOLERANCE
RATING
M8J53QI
(V)
(%)
(RMS) (DC)
(J)

CLAMPING
VOLTAGE
ATlOOA
(V)

CAPACITANCE
ATIMHz
(pF)

CLAMPING
VOLTAGE
AT PEAK
CURRENT
RATING
(V)

ITM
(A)

NEAREST
COMMERCIAL
EQUIVALENT

1-2000B

200

tl0

130

175

50

325

3800

570

6000 V130LA20B

1-22000

220

+10, -5

150

200

55

360

3200

650

6000 V150LA20B

14300E

430

+5, -to

275

369

100

680

1800

1200

6000 V275LA40B

1-5100E

5tO

+5, -10

320

420

120

810

1500

1450

6000 V320LA40B

This series of varistors are screened and conditioned in accordance with MIL-R-S3530 as outlined in Table 13.2. Manufactur-

Table 13.2. MIL-R-83530 Group A, B, and C Inspections
Group A Inspection
INSPECTION

Group B Inspection

AQL (pERCENT DEFECTIVE)

INSPECTION

SUBGROUP 1

SUBGROUP I

High Temperature Life
(stabilization bake)

Dielectric Withstanding Voltage

Thennal Shock

Solderability

SUBGROUP II
100%

Power Bum-In

Resistance to Solvents

Clamping Voltage

SUBGRoupm

Nominal Varistor Voltage

Terminal Strength (lead fatigue)
MAJOR

SUBGROUP 2

Moisture Resistance

MINOR

Peak Current

Visual and Mechanical
Examination

Energy

-

Body Dimensions
Diameter and Length of

1.0%AQL

Leads

7.6%LQ

Marking
Woriananship

25%AQL
13.0%LQ

Group C Inspection
INSPECTION

NUMBER OF
SAMPLE UNITS

FAILURES
ALLOWED

EVERY 3 MONTIIS
High Temperature Storage

10

0

Operating Life
(steady state)

10

0

Pulse Life

10

0

Shock

10

0

Vibration

10

0

Constant Acceleration

10

0

Energy

to

0

13-2

13.2 DESC SOURCE CONTROLLED DRAWING # 87063
Based on MIL-R-83530 ZA Package Series

Table 13.3 Ratings and Characteristics
MAXIMUM RATINGS (+8S"C)
CONTINUOUS

87063
DASH
NO.
001
002
003

004
005
006
007
008

009
010
011
012
013
014
015
016
017
018
019
020
021
022
023
024
025
026
027
028
029
030
031
032
033
034
035
036
037
038
039
040
041
042
043
044
045

046
047
048
049

OSO
051
052

NEAREST
COMM.
NO.
V2'1ZA05
V2'1ZA1
V2'1ZA2
V2'1ZA3
V24ZASO
V27ZA05
V27ZAI
V27ZA2
V27ZA4
V27ZA60
V33ZA05
V33ZA1
V33ZA2
V33ZAS
V33ZA70
V36ZA80
V39ZA05
V39ZAI
V39ZA3
V39ZA6
V47ZA05
V47ZAI
V47ZA3
V47ZA7
V56ZA05
V56ZA2
V56ZA3
V56ZA8
V68ZA05
V68ZA2
V68ZA3
V68ZAIO
V8'1ZA05
V8'1ZA2
V8'1ZA4
V8'1ZA12
VlOOZA05
V100ZA3
VlOOZA4
V100zA15
VI20ZA05
V12OZA1
VI20ZA4
V120ZA6
V15OZA05
V150ZA1
VI5OZA4
V150ZA8
V18OZA05
V1SOZAI
V1SOZAS
VI80ZAIO

RMS

DC

VMfAC1 VMfDC1

PEAK
CURRENT

lOOO~)

(8120j1s)

W TM

ITM
(A)

MIN
(V)

VNfDC1
(V)

MAX
(V)

Vc
(V)

35
150
350

18.7
18.7
18.7
18.7
19.2
23
23
23
23
23
29.5
29.5
29.5
29.5
29.5
32
35
35
35
35
42
42
42
42

22
22
22
22
24t
27
27
27
27
27t
33
33
33
33
33t
36t
39
39
39
39
47
47
47
47
56
56
56
56
68
68
68
68
82
82
82
82
100
100
100
100
120
120
120
120
150
ISO

26
26
26
26
26
31.1
31.1
31.1
31.1
31.1
38
36.5
36.5
36.5
36.5
40
46
43
43
43
55
52
52
52
66
62
62
62
80
75
75
75
97
91
91
91
117
110
110
110
138
132
132
132
173
165
165
165
207
198
198
198

51
47
43
43
43
59
57
53
53
50
67
68
64
64
58
63
79
79
76
76
90
92
89
89
108
107
103
103
127
127
123
123
145
135
135
145
175
165
165
175
205
205
200
210
240
250
250
255
290
295
300

(V)

(V)

(J)

1
2
3
4
5
I
2
3
4
5
I
2
3
4
5
5
1
2
3
4
I
2
3
4
I
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4

14
14
14
14
14
17
17
17
17
17
20
20
20
20
21
23
25
25
25
25
30
30
30
30
35
35
35
35
40
40
40
40
50
50
50
50
60
60

18
18
18
18
18
22
22
22
22
22
26
26
26
26
27
31
31
31
31
31
38
38
38
38
45
45
45
45
56
56
56
56
66
66
66
66
81
81
81
81
102
102
102
102
127
127
127
127
153
153
153
153

0.2
0.9
2.0
4.0
6.5
0.25
1.0
2.5
5.0
8.0
0.3
1.2
3.0
6.0
9.0
10.0
0.35
1.5
3.5
7.2
0.4
1.8
4.5
8.8
0.5
2.3
5.5
10.0
0.6
3.0
6.5
13.0
1.2
3.5
7.3
13.0
1.5
4.3
8.9
16.0
1.8
5.3
11.0
19.0
2.3
6.5
13.0
23.0
2.7
7.7
16.0
27.0

75
75
75
75
92
95
95
95
1I0
ll5
115
ll5

• SIze 1-5mm, 2-7mm, 3-10mrn, 4-14mm, 5-2Omm

7SO
1500
35
ISO
350
750
1500
35
150
350

7SO
1500
1500
35
150

3SO
750
35
ISO

3SO
750
35

ISO
350
750
35

ISO
350

7SO
70
300
750
1500
70
300

7SO
1500
100
400
1000
2000
100
400
1000
2000

ISO
500
1500

3000

t

VARISTOR VOLTAGE
@lmADC
TEST CURRENT

MAXIMUM
CLAMPING
VOLTAGE
Vc@TEST
CURRENT

ENERGY
(1111

SIZE"

60
60

CHARACTERISTICS (+2S"C)

TRANSIENT

SO
SO
SO
SO
61
61
61
61
73
73
73
73
90
90
90
90
108
108
108
108
135
135
135
135
162
162
162
162

ISO
150
180
180
180
180

Denotes 10mA DC test current.

13-3

(8120~)

300

TYPICAL
CAPACITANCE

Ie

C=lMHz

(A)

(pF)

2
5
5
10
20
2
5
5
10
20
2
5
5
10
20
20
2
5
5
10
2
5
5
10
2
5
5
10
2
5
5
10
2
10
25
50
2
10
25
50
2

400
1600
4000

10
25
50
2
10
25
50
2
10
25
50

9000
18000
300
1300
3000
7000
15000
250
1100
2700
6000
13000
12000
220
900
2200
5000
200
800
2000
4500
180
700
1800
3900
150
600
1500
3300
120
500
1100
2500
90
400
900
2000
70
300
750
1700

60
250
600
1400
50
200
500
1100

13.2 DESC STANDARD MILITARY DRAWING # 90065
Based on MIL-R-83530 DB Package Series
fible 13.4 Ratings and Characterlsdcs
MAX CLAMPING
VOLTAGE AT
TEST CURRENT

90065
DASH
NO.

VOLTAGE
RATING
MAX.
(RMS)

ENERGY
MAX
(J)

PEAK
CURRENT
(A)

NOMINAL
VARISTOR
VOLTAGE
(V)

(V)

(I)

TYPICAL
CAPACITANCE
(PF)

012

130

170

22500

200

+28, -16

345

200

10000

013

150

200

22500

240

±28

405

200

8000

014

250

270

22500

390

+39, -36

650

200

5000

015

275

300

22500

430

±43

730

200

4500

016

320

350

22500

510

+29,48

830

200

3800

017

420

460

28800

6SO

+68, -70

1130

200

3000

018

4SO

510

28800

750

+74, -so

1240

200

2700

019

510

550

28800

820

+91, -85

1350

200

2500

020

575

600

28800

910

+95, -105

14SO

200

2200

021

660

690

28800

1050

±110

1720

200

2000

022

750

810

28800

1200

±l20

2000

200

1800

13.2 DESC STANDARD MILITARY DRAWING # 88063
Based on MIL-R-83530 PA Package Series
fible 13.5 Ratings and Characterlsdcs
VOLTAGE
RATING
MAX.

NOMINAL
VARISTOR
VOLTAGE
(V)

MAX CLAMPING
VOLTAGE AT
TEST CURRENT

DASH
NO.

(RMS)

(DC)

ENERGY
MAX
(J)

(V)

(I)

001

130

175

70

6500

200

+43, -16

360

100

1900

002

130

175

70

6500

200

+20, -16

325

100

1900
1600

80063

PEAK
CURRENT
(A)

TYPICAL
CAPACITANCE
(pF)

003

150

200

80

6500

240

+44, -28

420

100

004

150

200

so

6500

240

+3, -28

360

100

1600

005

250

330

130

6500

390

+63,-36

675

100

1000

006

250

330

130

6500

390

+23, -36

620

100

1000

007

275

369

140

6500

430

+64,41

740

100

900

008

275

369

140

6500

430

+23,41

6SO

100

900

009

320

420

160

6500

510

+55,48

850

100

750

010

320

420

160

6500

510

+30,48

800

100

750

011

420

560

160

6500

6SO

+110, -70

1160

100

600

012

420

560

160

6500

6SO

+10, -70

1050

100

600

013

4SO

640

ISO

6500

750

+110, -80

12SO

100

550

014

4SO

640

ISO

6500

750

+40, -SO

1160

100

550

015

510

675

190

6500

820

+143, -85

1410

100

500

016

510

675

190

6500

820

+40,-85

12SO

100

500
450

017

575

730

220

6500

910

+140, -105

1560

100

018

575

730

220

6500

910

+50, -105

1410

100

450

019

660

850

250

6500

1050

+160, -110

1820

100

400

020

660

850

250

6500

1050

+50, -110

1650

100

400

13-4

13.3 HARRIS IDGH RELIABILITY SERIES TX EQUIVALENTS
Table 13.6. Available TX Model Types
NEAREST
COMMERCIAL
EQUIVALENT

NEAREST
COMMERCIAL
EQUIVALENT

MODEL
SIZE

DEVICE
MARK

VSZTXl

7mm

8TXl

V8ZAI

VI30LTX2

7mm

l30TX

VSZTX2

IOmm

8TX2

V8ZA2

VI30LTXI0A

14mm

13OTXlO

VI2ZTXl

7mm

12TXl

VI2ZAI

VI3OLTX20B

20mm

130TX20

VI2ZTX2

IOmm

12TX2

VI2ZA2

VISOLTX2

7mm

150TX

V22ZTXl

7mm

22TXl

V22ZAI

VISOLTXI0A

14mm

15OTXlO

VI50LAI0A

V22ZTX3

14mm

22TX3

V22ZA3

VI50LTX20B

20mm

15OTX20

VISOLA20B

V24ZTX50

20mm

24TX50

V24ZASO

V2SOLTX4

7mm

250TX

V33ZTXl

7mm

33TXl

V33ZAI

V2SOLTX2OA

I4mm

2S0TX20

V250LA20A

V33ZTX5

14mm

33TX5

V33ZAS

V2SOLTX40B

20mm

2SOTX40

V2SOLA40B

V33ZTX70

20mm

33TX70

V33ZA70

V420LTX20A

14mm

42OTX20

V420LA20A

TXMODEL

TXMODEL

MODEL
SIZE

DEVICE
MARK

VI30LA2
V130LAI0A
VI30LA20A
V150LA2

V250LA4

V68ZTX2

7mm

68TX2

V68ZA2

V420LTX40B

20mm

42OTX40

V420LA40B

V68ZTXlO

14mm

68TXI0

V68ZAI0

V48OLTX40A

14mm

48OTX40

V4SOLA40A

V82ZTX2

7mm

82TX2

V82ZA2

V48OLTXSOB

20mm

48OTXSO

V480LASOB

V82ZTX12

14mm

82TX12

V82ZA12

V510LTX40A

14mm

SIOTX40

V51OLA40A

V510LTXSOB

20mm

51OTXSO

V51OLASOB

This series of varistors are 100% screened and conditioned in accordance with MIL-STD-750. Tests are as outlined in
Table 13.7.
INSPECTION LOTS
FORMED AFTER i---I
ASSEMBLY

LOTS PROPOSED
FOR TX TVPES

r-

100% SCREENING

I---'

REVIEW OF DATA
TX PREPARATION 1""-""1
FOR DELIVERY

QA ACCEPTANCE
SAMPLE PER
APPLICABLE DEVICE
SPECIFICATION

Table 13.7. TX Equivalents Series 100% Screening
SCREEN

MIL-8TD-7SO
METHOD

CONDITION

TX
REQUIREMENTS

High Temperature Life
(stabilization bake)

1032

24 hours min. at max. rated storage temperature.

100%

Tbennal Shock
(temperature cycling)

1051

No dwell is required at 2S"C. Test condition AI,S cycles SS" C to +12S"C (extremes). > 10 minutes

100%

Humidity Life

85"C, 85% R.H., 168 hours.

Interim Electrical VN(DC) VC
(Note 1)

As specified, but including delta parameter as a
minimum.

Power Burn-In

1038

Final Electrical +V N(DC) VC
(Note 1)
External Visual Examination

Condition B, 8S"C, Rated VM(AC)' 72 hours nunln

As speclfled - All parameter measurements must be completed within 96 hours after removal from burn-in conditions.
2071

To be performed after complete marking.

NOTE:
1. Delta Parameter - VN(DC)
Maximum allowable shift ±10% Max.
Applicable lot PDA - 10% Max.
Peak current and energy ratings are derated by 10% and 30%, respectively, from standard parts.

13-5

100%
100% Screen

100%
100% Screen

100%

13.3 HARRIS IDGH RELIABILITY SERIES TX EQUIVALENTS (Continued)
Table 13.8. Quality Assurance Acceptance Test
MIL-S'fD.I05
LEVEL

AQL

Electrical (Bi-directional)
VN(DC)' V C (per characteristics table)

II

0.1

Dielectric Withstand Voltage
MlL-STD-202, Method 301, 2500V min. at 1.0llAdc

-

-

15

-

-

15

Solderability
MlL-STD-202, Method 208, no aging, non-activated

LTPD

13.4 CUSTOM TYPES
In addition to our comprehensive high-reliability series as referenced above, Harris can screen and condition to customer-specific requirements.
Additional mechanical and environmental capabilities are defined in Table 13.9.
Table 13.9. Mechanical and Environmental Capabilities (Typical Conditions)
TEST NAME

TESTMEmOD

DESCRIPTION

Tenninal Strength

MlL-SID-750-2036

3 bends, 90" arc, 16 oz. weight

Drop Shock

MlL-SID-750-2016

1500 g's, O.5ms, 5 pulses, XI' V I' ZI

Variable Frequency Vibration

MIL-STD-7 50-2056

20 g's, IOO-2000Hz, XI' VI' Zi

Constant Acceleration

MIL-STD-750-2006

V2' 20,000 g's min

Salt Armosphere

MIL-SID-750-1041

35° C, 24 hrs, 10-50 g1rr1 day

Soldering HeatlSolderahility

MlL-STD-750-203112026

260" C, lOs, 3 cycles, test marking

Resistance to Solvents

MIL-STD-202-215

pennanence, 3 solvents

Flammability

MIL-STD-202-111

15s torching, lOs to flameout

Flammability

UL1414

Cyclical Moisture Resistance

MIL-STD-202-106

3 x 15s torching
10 days

Steady-State Moisture Resistance

85/85 96 hrs.

Biased Moisture Resistance

Not recommended fOl" high-voltage types

Temperature Cycle

MlL-STD-202-107

-55 to +125"C, 5 cycles

High-Temperature Life (Nonoperating)

MIL-SID-750-1032

1250 C, 24 hrs.

Bum-In

MIL-SID-750-1038

Rated temperature and V RMS

Hermetic Seal

MIL-SID-7 50-1 071

ConditionD

13-6

13.5 RADIATION HARDNESS
For space applications, an extremely important property of a protection device is its response to imposed radiation effects.
Electron Irradiation

A Harris MaV and a silicon transient suppression diode were exposed to electron irradiation. The V-I Curves, before and after
test, are shown in Figure 13.1.

v
200

1

100
80

-/

HARRISMOV

~

.'
.... '...'.'

.. ..
'

SlUCON TRANSIENT SUPPRESSION DIODE

,

••..
.

60

40
-

PRETEST

. , , ' ' ' ' ' ' 10· RADS, 18MeV ELECTRONS

I

I

104
CURRENT (AMPERES)

Figure 13.1. Radiation Sensitivity of Harris VI30LAI and Silicon Transient Suppression Diode

It is apparent that the Harris MaV was virtually unaffected, even at the extremely high dose of 108 rads, while the silicon transient suppression diode showed a dramatic increase in leakage current.
Neutron Effects

A second MaV-Zener comparison was made in response to neutron fluence. The selected devices were equal in area.
Figure 13.2 shows the clamping voltage response of the MaV and the zener to neutron irradiation to as high as 1015 N/cm2. It
is apparent that in contrast to the large change in the zener, the MaV is unaltered. At higher currents where the MaV's clamping voltage is again unchanged, the zener device clamping voltage increases by as much as 36%.
Counterclockwise rotation of the V-I characteristics is observed in silicon devices at high neutron irradiation levels; in other
words, increasing leakage at low current levels and increasing clamping voltage at higher current levels.
The solid and open circles for a given fluence represent the high and low breakdown currents for the sample of devices tested.
Note that there is a marked decrease in current (or energy) handling capability with increased neutron fluence.
Failure threshold of silicon semiconductor junctions is further reduced when high or rapidly increasing currents are applied.
Junctions develop hot spots, which enlarge until a short occurs if current is not limited or quickly removed.

13-7

300

200

II IIIII""

1.~K ~IILI~~L

II
:::

VARISTOR V130A2
INITIAL AT 10IS

..

/""

/~

/1

LI

100

,

80
80

1.5K200
AT 1012

so

I

40
30

1.5K2~

20

10
10

10

IIHi
106

I
1.J200

I

II
II

1.5K200
AT1015

[in II
107

10'

105

103

AMPERES

Figure 13.2. V-I Characteristic Response to Neutron Irradiation for MOV and Zener Diode Devices
The characteristic voltage current relationship of a PN-Iunction is shown in Figure 13.3.
SATURATION
CURRENT

REOUCTIONIN
FAILURE STI~ESiSHIOLC
BY RADIAL

REVERSE
BIAS

Figure 13.3. V-I Characteristic ofPN-Junction
At low reverse voltage, the device will conduct very little current (the saturation current). At higher reverse voltage VBO
(breakdown voltage), the current increases rapidly as the electrons are either pulled by the electric field (Zener effect) or
knocked out by other electrons (avalanching). A further increase in voltage causes the device to exhibit a negative resistance
characteristic leading to secondary breakdown.
This manifests itself through the fonnation of hotspots, and irreversible damage occurs. This failure threshold decreases under
neutron irradiation for zeners, but not for Zinc Oxide Varistors.

Gamma Radiation
Radiation damage studies were performed on type V-I 30LA2 varistors. Emission spectra and V-I characteristics were
collected before and after irradiation with 106 rads CoOO gamma radiation.
Both show no change, within experimental error, after irradiation.

13-8

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SG103

CMOS LOGIC SELECTION GUIDE (1994: 2BBpp) This product selection guide contains technical Information on Harris
Semiconductor High Speed 54/74 CMOS Logic Integrated Circuits for commercial, Industrial and military applications. It
covers Harris' High Speed CMOS Logic HCIHCT Series, AC/ACT Series, 6iCMOS Interface Logic FCT Series and CMOS
Logic CD40006 Series.

PSG201.21

PRODUCT SELECTION GUIDE (NEW 1994: 616pp) Key product Information on all Harris Semiconductor devices.
Sectioned (Linear, Data Acquisition, Oigltal Signal Processing, Telecom, Intelligent Power, Discrete Power, Oigital
Microprocessors and Hi-ReVMllitary and Rad Hard) for easy use and Includes cross references and alphanumeric part
number index.

DB500B

LINEAR AND TELECOM ICs (1993: l,312pp) Product specifications for. op amps, comparators, s/H amps, differential
amps, arrays, special analog circuits, telecom ICs, and power processing circuits.

OB301B

DATA ACQUISITION (1994: l,104pp) Product specifications on AlO converters (display, integrating, successive
approximation, flash); D/A converters, switches, multiplexers, and other products.

063026

DIGITAL SIGNAL PROCESSING (1994: 52Bpp) Product specifications on one-dimensional and two-dimensional filters,
signal synthesizers, multipliers, special function devices (such as address sequencers, binary correlators, histogrammer).

OB304.1

INTELLIGENT POWER ICs (1994: 946pp) This data book includes a complete set of data sheets for product specifications,
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OB450C

TRANSIENT VOLTAGE SUPPRESSION DEVICES (1994: 400pp) Product specifications of Harris varistors and surgectors.
Also, general informational chapters such as: "Voltage Transients - An Overview," "Transient Suppression - Devices and
Principles," 'Suppression - Automotive Transients."

OB223B

POWER MOSFETs (1994: l,328pp) This data book contains detailed technical information including standard power
MOSFETs (the popular RF-series types, the IRF-series of industry replacement types, and JEDEC types), MegaFETs, logiclevel power MOSFETs (L2 FETs), ruggedized power MOSFETs, advanced discrete, high-reliability and radiation-hardened
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OB220.1

BIPOLAR POWER TRANSISTORS (1992: 592pp) Technical information on over 750 power transistors for use in a wide
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OB235B

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ACTS logic families, SRAMs, PROMs, op amps, analog multiplexers, the 80C85/80C86 microprocessor family, analog
switches, gate arrays, standard celis and custom devices.

DB260.2

CDP6805 CMOS MICROCONTROLLERS & PERIPHERALS (1995: 436pp) This data book represents the full line of Harris
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under the Harris, GE, RCA or Intersll names.

DB303

MICROPROCESSOR PRODUCTS (1992: l,156pp) For commerCial and military applications. Product specifications on
CMOS microprocessors, peripherals, data communications, and memory ICs.

DB309

MCTnGBTIDIODES (1994: 528pp) This data book fully describes Harris Semiconductor's line of MOS Controlled Thyristors,
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Analog
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ANALOG MILITARY (1989: l,264pp) This data book describes Harris' military line of Linear, Data Acquisition, and
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DB312

ANALOG MILITARY DATA BOOK SUPPLEMENT (1994: 432pp) The 1994 Military Data Book Supplement, combined with
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Application Note Listing
AnswerFAX
DOCUMENT
NUMBER

PART
NUMBER

9001

ANOO1

Glossary of Data Conversion Terms
(6 pages)

9002

ANOO2

9004

AnswerFAX
DOCUMENT
NUMBER

PART
NUMBER

9054

AN054

Principles of Data Acquisition and Conversion (20 pages)

Display Driver Family Combines Convenience of Use with Microprocessor
Interfaceability (18 pages)

9108

AN108

AN004

The IH5009 Analog Switch Series
(9 pages)

82C52 Programmable UART
(12 pages)

9109

AN109

9007

AN007

Using the 804818049 Log/Antilog Amplifier (6 pages)

82C59A Priority Interrupt Controller
(14 pages)

9111

AN111

9009

AN009

Pick Sample-Holds by Accuracy and
Speed and Keep Hold Capacitors in
Mind (7 pages)

Harris 80C286 Performance Advantages Over the 80386 (12 pages)

9112

AN112

DESCRIPTION

9013

AN013

Everything You Always Wanted to
Know About the ICL8038 (4 pages)

DESCRIPTION

80C286/80386 Hardware Comparison
(4 pages)

9113

AN113

Some Applications of Digital Signal Processing Techniques to Digital Video
(5 pages)

9114

AN114

Real-Time Two-Dimensional Spatial Filtering with the Harris Digital Filter Family (43 pages)
Digital Filter (OF) Family Overview
(6 pages)

9016

AN016

Selecting NO Converters (7 pages)

9017

AN017

The Integrating NO Converter
(5 pages)

9018

AN018

Do's and Don'ts of Applying NO Converters (4 pages)

9115

AN115

9023

AN023

Low Cost Digital Panel Meter Designs
(5 pages)

9116

AN116

Extended OF Configurations (10 pages)

9120

AN120

Interfacing the 80C286-16 With the
80287-10 (2 pages)

9121

AN121

Harris 80C286 Performance Advantages Over the 80386SX (14 pages)

9400

AN400

Using the HS-3282 ARINC Bus Interface Circuit (6 pages)

9509

AN509

A Simple Comparator Using the
HA-2620 (1 page)

9514

AN514

The HA-2400 PRAM Four Channel Operational Amplifier (7 pages)

9027

AN027

Power Supply Design Using the
ICL8211 and 8212 (8 pages)

9028

AN028

Build an Auto-Ranging DMM with the
ICL7103N8052A NO Converter Pair
(6 pages)

9030

AN030

ICL7104: A Binary Output NO Converter for Microprocessors (16 pages)

9032

AN032

Understanding the Auto-Zero and
Common Mode Performance of the
ICL7106n107n109 Family (8 pages)

9040

AN040

Using the ICL8013 Four Quadrant Analog Multiplier (6 pages)

9515

AN515

Operational Amplifier Stability: Input
Capacitance Considerations (2 pages)

9042

AN042

Interpretation of Data Converter Accuracy Specifications (11 pages)

9517

AN517

Applications of Monolithic Sample and
Hold Amplifier (5 pages)

9046

AN046

Building a Battery Operated Auto Ranging DVM with the ICL7106 (5 pages)

9519

ANS19

Operational Amplifier Noise Prediction
(4 pages)

9520

ANS20

CMOS Analog Miltiplexers and Switches; Applications Considerations
(9 pages)

9048

AN048

Know Your Converter Codes (5 pages)

9049

AN049

Applying the 7109 NO Converter
(5 pages)

9051

AN051

Principles and Applications of the
ICL7660 CMOS Voltage Converter
(9 pages)

9522

AN522

Digital to Analog Converter Terminology (3 pages)

9524

ANS24

9052

AN052

Tips for Using Single Chip 3.5 Digit NO
Converters (9 pages)

Digital to Analog Converter High Speed
ADC Applications (3 pages)

9525

ANS25

9053

AN053

The ICL7650 A New Era in Glitch-Free
Chopper Stabilized Amplifiers
(19 pages)

HA-S190/5195 Fast Settling Operational Amplifier (4 pages)

9526

ANS26

Video Applications for the HA-S1901
5195 (S pages)

9531

ANS31

Analog Switch Applications in NO Data
Conversion Systems (4 pages)

14-4

AnswerFAX Technical Support
Application Note Listing (Continued)
AnswerFAX
DOCUMENT
NUMBER

PART
NUMBER

9532

AN532

9534

AnswerFAX
DOCUMENT
NUMBER

PART
NUMBER

Common Questions Concerning CMOS
Analog Switches (4 pages)

9607

AN607

Delta Modulation for Voice Transmission (5 pages)

AN534

Additional Information on the HI-300
Series Switch (5 pages)

95290

AN5290

Integrated Circuit Operational Amplifiers (20 pages)

9535

AN535

Design Considerations for A Data Acquisition System (DAS) (7 pages)

96048

AN6048

Some Applications of A Programmable
Power Switch/Amp (12 pages)
•

9538

AN538

Monolithic SampleIHold Combines
Speed and Precision (6 pages)

96077

AN6077

9539

AN539

A Monolithic 16-Bit D/A Converter
(5 pages)

An IC Operational-TransconductanceAmplifier (OTA) With Power Capability
(12 pages)

96157

AN6157

9540

AN540

HA-5170 Precision Low Noise JFET Input Operation Amplifier (4 pages)

Applications of the CA3085 Series
Monolithic IC Voltage Regulators
(11 pages)

9541

AN541

Using HA-2539 or HA-2540 Very High
Slew Rate. Wideband Operational Amplifier (4 pages)

96182

AN6182

Features and Applications of Integrated
Circuit Zero-Voltage Switches
(CA3058. CA3059 and CA3079)
(31 pages)

9543

AN543

New High Speed Switch Offers Sub50ns Switching Times (7 pages)

96386

AN6386

9544

AN544

Micropower Op Amp Family (6 pages)

Understanding and Using the CA3130.
CA3130A and CA3130B30Al30B
BiMOS Operation Amplifiers (5 pages)

9546

AN546

A Method of Calculating HA-2625 Gain
Bandwidth Product vs. Temperature
(4 pages)

96459

AN6459

Why Use the CMOS Operational Amplifiers and How to Use it (4 pages)

96869

AN6669

9548

AN548

A Designers Guide for the HA-5033 Video Buffer (12 pages)

FET-Bipolar Monolithic Op Amps Mate
Directly to Sensitive Sources (3 pages)

96915

AN6915

9549

AN549

The HC-550X Telephone Subscriber
Line Interface Circuits (SLlC)
(19 pages)

Application of CA 1524 Series PulseWidth Modulator ICs (18 pages)

96970

AN6970

Understanding and Using the CDP1 855
MultiplylDivide Unit (11 pages)

97063

AN7063

Understanding the CDP1851 Programmable I/O (7 pages)

97174

AN7174

The CA 1524E Pulse-Width ModulatorDriver for an Electronic Scale (2 pages)

DESCRIPTION

DESCRIPTION

9550

AN550

Using the HA-2541 (6 pages)

9551

AN551

Recommended Test Procedures for
Operational Amplifiers (6 pages)

9552

AN552

Using the HA-2542 (5 pages)

9553

AN553

HA-5147/37/27. Ultra Low Noise Amplifiers (8 pages)

97244

AN7244

Understanding Power MOSFETs
(4 pages)

9554

AN554

Low Noise Family HA-5101/02/04/11/
12/14 (7 pages)

97254

AN7254

9556

AN556

Thermal Safe-Operating-Areas for High
Current Op Amps (5 pages)

Switching Waveforms of the L2FET:
A 5 Volt Gate-Drive Power MOSFET
(8 pages)

97260

AN7260

Power MOSFET Switching Waveforms:
A New Insight (7 pages)

9557

AN557

Recommended Test Procedures for Analog Switches (6 pages)

97326

AN7326

9558

AN558

Using the HV-1205 AC to DC Converter
(2 pages)

Applications of the CA3228E Speed
Control System (16 pages)

97332

AN7332

9559

AN559

HI-222 VideolHF Switch Optimizes Key
Parameters (7 pages)

The Application of Conductivity-Modulated Field-Effect Transistors (5 pages)

98602

AN8602

The IGBTs - A New High Conductance
MaS-Gated Device (3 pages)

98603

AN8603

Improved IGBTs with Fast Switching
Speed and High-Current Capability
(4 pages)

9571

AN571

Using Ring Sync with HC-5502A and
HC-5504 SLiCs (2 pages)

9573

AN573

The HC-5560 Digital Line Transcoder
(6 pages)

9574

AN574

Understanding PCM Coding (3 pages)

9576

AN576

HC-5512 PCM Filter Cleans Up CVSD
Codec Signals (2 pages)

98610

14-5

AN8610

Spicing-Up Spice II Software for Power
MOSFET Modeling (8 pages)

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15
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P.O. Box 591
Somerville, NJ 08876
TEL: (908) 685-6150
FAX: 908 685-6140
Tritek Sales, Inc.
One Mall Dr., Suite 41 0
Cherry Hill, NJ 08002
TEL: (609) 667-0200
FAX: 609 6678741
NEW MEXICO
Compass Mktg. & Sales, Inc.
4100 Osuna Rd., NE, Suite 109
Albuquerque, NM 87109
TEL: (505) 344-9990
FAX: 505 345 4848

Advanced Tech Sales, Inc.
348 Park Street, Suite 102
Park Place West
N. Reading, MA 01864
TEL: (508) 664-0888
FAX: 508 664 5503

NEW YORK
Harris Semiconductor
Hampton Business Center
1611 At. 9, Surre U3
Wappingers Falls, NY 12590
TEL: (914) 298-0413
FAX: 914 298 0425

MICHIGAN
Harris Semiconductor
• 27777 Franklin Rd., Suite 460
Southfield, MI 48034
TEL: (810) 746-0800
FAX: 810 7460516
Glestlng & Associates
34441 Eight Mile Ad., Suite 113
Livonia, MI 48152
TEL: (810) 478-8106
FAX: 810 477 6908

Harris Semiconductor
• 490 Wheeler Ad, Suite 165B
Hauppauge, NY 11788-4365
TEL: (516) 342-0219
FAX: 516 342 0295

• Field Application Assistance Available

15-2

Foster & Wager, Inc.
300 Main Street
Vestal, NY 13850
TEL: (607) 748-5963
FAX: 6077485965

North American Sales Offices and Representatives (Continued)
Foster & Wager, Inc.
2511 Browncroft Blvd.
Rochester, NY 14625
TEL: (716) 385-7744
FAX: 7165861359
Foster & Wager, Inc.
7696 Mountain Ash
Liverpool, NY 13090
TEL: (315) 457-7954
FAX: 315 457 7076
Trlonlc Associates, Inc.
320 Northern Blvd.
Great Neck, NY 11021
TEL: (516) 466-2300
FAX: 516 466 2319
NORTH CAROLINA
Harris Semiconductor
4020 Stirrup Creek Dr.
BUilding 2A, MS/2T08
Durham, NC 27703
TEL: (919) 405-3600
FAX: 919 405 3660

OHIO
Glestlng & Associates
P.O. Box 39398
2854 Blue Rock Rd.
Cincinnati, OH 45239
TEL: (513) 385-1105
FAX: 513 385 5069
6324 Tamworth CI.
Columbus, OH 43017
TEL: (614) 752-5900
6200 SOM Center Rd.
SUite 0-20
Solon, OH 44139
TEL: (216) 498-4644
FAX: 216 498 4554
OKLAHOMA
Nova Marketing
8421 East 61st Street, SUite P
Tulsa, OK 74133-1928
TEL: (800) 826-8557
TEL: (918) 660-5105
FAX: 918 3571091

OREGO'N
Northwest Marketing Assoc.
6975 SW Sandburg Rd.
Suite 330
Portland, OR 97223
TEL: (503) 620-0441
FAX: 503 684 2541
PENNSYLVANIA
Glesting & Associates
471 Walnut Street
Pittsburgh, PA 15238
TEL: (412) 828-3553
FAX: 412 828 6160
TEXAS
Harris Semiconductor
• 17000 DaUas Parkway, Suite 205
Dallas, TX 75248
TEL: (214) 733-0800
FAX: 214 733 0819
Nova Marketing
8310 Capitol of Texas Hwy.
Suite 180
Austin, TX 78731
TEL: (512) 343-2321
FAX: 512 343-2487

New Era Sales
1215 Jones Franklin Road
Suite 201
Raleigh, NC 27606
TEL: (919) 859-4400
FAX: 919 859 6167

February 24, 1995
8350 Meadow Rd., Suite 174
Dallas, TX 75231
TEL: (214) 265-4600
FAX: 214 265 4668
Corporate Atrium II, Suite 140
10701 Corporate Dr.
Stafford, TX 77477
TEL: (713) 240-6082
FAX: 7132406094
UTAH
Compass Mktg. & Sales, Inc.
5 Triad Center, Suite 320
Salt Lake City, UT 84180
TEL: (801) 322-0391
FAX: 801 322-0392
WASHINGTON
Northwest Marketing Assoc.
12835 Bel-Red Road
Suile330N
Bellevue, WA 98005
TEL: (206) 455-5846
FAX: 206 4511130
WISCONSIN
Oasis Sales
1305 N. Barker Rd.
Brookfield, WI 53005
TEL: (414) 782-6660
FAX: 4147827921

North American Authorized Distributors and Corporate Offices
Hamilton Hallmark and Zeus are the only authorized North American distributors for stocking and sale of Harris Red Hard Space products.
Alliance Electronics
7550 E. Redfield Rd.
Scottsdale, PIZ. 85260
TEL: (602) 483-9400
FAX: (602) 443 3898
Arrow/Schweber
Electronics Group
25 Hub Dr.
Melville, NY 11747
TEL: (516) 391-1300
FAX: 5163911644
Electronics Marketing
Corporation (EMC)
1150 WestThird Avenue
Columbus, OH 43212
TEL: (614) 299-4161
FAX: 6142994121

Farnell Electronic Services
300 North Rivermede Rd.
Concord, OntariO
Canada L4K 3N6
TEL: (416) 798-4884
FAX: 4167984689

Hamilton Hallmark
10950 W. Washington Blvd.
Culver City, CA 90230
TEL: (310) 558-2000
FAX: 310 558 2809 (Mil)
FAX: 214 343 5988(Com)

Gerber Electronics
128 Carnegie Row
Norwood, MA 02062
TEL: (617) 769-6000, x156
FAX: 617 762 8931

Newark Electronics
4801 N. Ravenswood
Chicago, IL 60640
TEL: (312) 784-5100
FAX: 312 275-9596
Wyle Electronics
(Commercial Products)
3000 Bowers Avenue
Santa Clara, CA 95051
TEL: (408) 727-2500
FAX: 408 988-2747

Zeus Electronics,
An Arrow Company
100 Midland Avenue
PI. Chester, NY 10573
TEL: (914) 937-7400
TEL: (800) 52-HI-REL
FAX: 914 937-2553

Obsolete Products:
Rochester Electronic
10 Malcom Hoyt Drive
NeWburyport, MA 01950
TEL: (508) 462-9332
FAX: 508 462 9512

North American Authorized Distributors
ALABAMA
Arrow/schweber
Huntsville
TEL: (205) 837-6955
Hamilton Hallmark
Huntsville
TEL: (205) 837-8700
Wyle Electronics
Huntsville
TEL: 205) 830-1119
Zeus, An Arrow Company
Huntsville
TEL: (407) 333-3055
TEL: (800) 52-HI-REL

Zeus, An Arrow Company
Tempe
TEL: (408) 629-4789
TEL: (800) 52-HI-REL

ARIZONA
Alliance Electronics, Inc.
Gilbert
TEL: (802) 813-0233
Scottsdale
TEL: (602) 483-9400
Arrow/schweber
Tempe
TEL: (602) 431-0030

CALIFORNIA
Alliance Electronics, Inc.
Santa Clarita
TEL: (805) 297-6204
Arrow/schweber
Calabasas
TEL: (818) 880-9686

Hamilton Hallmark
Phoenix
TEL: (602) 437-1200
Wyle Electronics
Phoenix
TEL: (602) 437-2088

• Field Application Assistance Available
15-3

San Diego
TEL: (619) 565-4800
San Jose
TEL: (408) 441-9700
Hamilton Hallmark
Costa Mesa
TEL: (714) 641-4100
Los Angeles
TEL: (818) 594-0404

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Sacramento
TEL: (916) 624-9781

LL

Fremont
TEL: (408) 432-7171

San Diego
TEL: (619) 571-7540

Irvine
TEL: (714) 587-0404

San Jose
TEL: (408) 435-3500

u:::

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North American Authorized Distributors (Continued)
Wyle Electronics
Calabasas
TEL: (818) 880-9000
Irvine
TEL: (714) 863-9953
Rancho Cordova
TEl: (916) 638-5282

CONNECTICUT
Alliance Electronics, Inc.
Shelton
TEL: (203).926-0087

San Diego
TEL: (619) 565-9171

ArrowlSchweber
Wallingford
TEL: (203) 265-7741
Hamilton Hallmark
Danbury
TEL: (203) 271·2844

Santa Clara
TEL: (408) 727-2500
Zeus, An Arrow Company .
San Jose
TEL: (408) 629·4789
TEL: (800) 52-HI·REl
Irvine
TEL: (714) 921-9000
TEL: (800) 52-HI-REl
CANADA
ArrowlSchweber
Burnaby, British Columbia
TEL: (804) 421·2333

Zeus, An Arrow Company
TEL: (914) 937-7400
TEL: (800) 52-HI-REl
FLORIDA
ArrowlSchweber
Deerfield Beach
TEL: (305) 429-8200
Lake Mary
TEL: (407) 333·9300

Dorval, Quebec
TEL: (514) 421-7411

Hamilton Hallmark
Miami
TEL: (305) 484-5482

Nepan, Ontario
TEL: (613) 226-6903

largo
TEL: (813) 541-7440
Wyle Electronics
Fort Lauderdale
TEL: (305) 420·0500
St. Petersburg
TEL: (813) 576-3004

Calgary, Alberta
TEL: (403) 273-2780
Concord, Ontario
TEL: (416) 798-4884

Zeus, An Arrow Company
lake Mary
TEL: (407) 333-3055
TEL: (800) 52-HI-REL

V. St. Laurent, Quebec
TEL: (514) 335-7697

Hamilton Hallmark
Mississagua, Ontario
TEL: (905) 564·6060

GEORGIA
ArrowlSchweber
Duluth
TEL: (404) 497-1300
Hamilton Hallmark
Atlanta
TEL: (404) 623-5475

Montreal
TEL: (514) 335·1000
Ottawa
TEL: (613) 226-1700

Wyle Electronics
Duluth
TEL: (404) 441-9045

Vancouver, B.C.
TEL: (804) 420-4101

Zaus, An Arrow Company
TEL: (407) 333·3055
TEL: (800) 52-HI-REL

Toronto
TEL: (905) 564·6060
COLORADO
Arrow/schweber
Englewood
TEL: (303) 799-0258

INDIANA
ArrowlSchweber
Indianapolis
TEL: (317) 299-2071
Hamilton Hallmark
Indianapolis
TEL: (317) 872-8875
Zeus, An Arrow Company
TEL: (708) 250-0500
TEL: (800) 52-HI-REl
IOWA
ArrowlSchweber
Cedar Rapids
TEL: (319) 395-7230
Hamilton Hallmark
Cedar Rapids
TEL: (319) 362-4757
Zeus, An Arrow Company
TEL: (214) 380-4330
TEL: (800) 52·HI·REl

Orlando
TEL: (407) 657-3300

Mississagua, OntariO
TEL: (905) 670-7769
Farnell Electronic Services
Burnaby, British Columbia
TEL: (604) 291-8866

Nepean, OntariO
TEL: (613) 596·6980
Winnipeg, Manitoba
TEL: (204) 786-2589

Wyle Electronics
Addison
TEL: (708) 620-0969
Zeus, An Arrow Company
Itasca
TEL: (706) 250·0500
TEL: (800) 52-HI·REL

Zeus, An A"ow Company
TEL: (408) 629-4789
TEL: (800) 52-HI-REL

ILLINOIS
Alliance Electronics, Inc.
Vernon Hills
TEL: (708) 949-9890

Hamilton Hallmark
Denver
TEL: (303) 790-1662
Coiorado Springs
TEL: (719) 637·0055
Wyle Electronics
Thornton
TEL: (303) 457·9953

Arrow/Schweber
Itasca
TEL: (708) 250·0500
Hamilton Hallmark
Chicago
TEL: (708) 860-7760
Newark Electronics, Inc.
Chicago
TEL: (312) 907-5436

KANSAS
ArrowlSchweber
Lenexa
TEL: (913) 541·9542
Hamilton Hallmark
Kansas City
TEL: (913) 888-4747
Zeus, An Arrow Company
TEL: (214) 380-4330
TEL: (800) 52·HI-REL
MARYLAND
ArrowlSchweber
Columbia
TEL: (301) 596·7800
Hamilton Hallmark
Baltimore
TEL: (410) 988·9800
Wyle Electronics
Columbia
TEL: (410) 312-4844
Zeus, An Arrow Company
TEL: (914) 937·7400
TEL: (800) 52-HI·REL
MASSACHUSETTS
Alliance Electronics, Inc.
Winchester
TEL: (617) 756·1910
Arrow/schweber
Wilmington
TEL: (508) 658-0900
Gerber
Norwood
TEL: (617) 769-6000
Hamilton Hallmark
Peabody
TEL: (508) 532·9893
Wyle Electronics
Burlington
(611) 272-7300

• Fieid Application Assistance Available

15-4

February 24, 1995
Zeus, An Arrow Company
Wilmington, MA
TEL: (508) 658-4776
TEL: (800) HI-REL
MICHIGAN
ArrowlSchweber
Livonia
TEL: (313) 462·2290
Hamilton Hallmark
Detroit
TEL: (313) 347-4271
Zeus, An Arrow Company
TEL: (708) 250-0500
TEL: (800) 52·Hi-REL
MINNESOTA
Arrow/schweber
Eden Prarie
TEL: (612) 941-5280
Hamilton Hallmark
MinneapoliS
TEL: (612) 881-2600
Wyle Electronics
Minneapolis
TEL: (612) 853-2280
Zeus, An Arrow Company
TEL: (214) 380-4330
TEL: (800) 52-Hi-REL
MISSOURI
Arrow/schweber
St.Louis
TEL: (314) 567-6888
Hamilton Hallmark
St. Louis
TEL: (314) 291-5350
Zeus, An Arrow Company
TEL: (214) 380-4330
TEL: (800) 52·HI-REL
NEW JERSEY
Arrow/schweber
Marlton
TEL: (609) 596-6000
Pinebrook
TEL: (201) 227-7680
Hamilton Hallmark
Cherry Hill
TEL: (609) 424-0110
Parsippany
TEL: (201) 515-1641
Wyte Electronics
Mt. Laurel
TEL: (609) 439·9110
Pine Brook
TEL: (201) 882-8358
Zeus, An Arrow Company
TEL: (914) 937-7400
TEL: (800) 52-HI·REL
NEW MEXICO
Hamilton Hallmark
Albuquerque
TEL: (505) 828-1058
Zeus, An Arrow Company
TEL: (408) 629-4789
TEL: (800) 52·Hi-REL

North American Authorized Distributors (Continued)
NEW YORK
Alliance Electronics, Inc.
Binghamlon
TEL: (607) 648-8833
Huntington
TEL: (516) 673-1930
Arrow/schwebar
Farmingdale
TEL: (516) 293·6363
Hauppauge
TEL: (516) 231·1000
Melville
TEL: (516) 391·1276
TEL: (516) 391-1300
TEL: (516) 391-1633
Rochester
TEL: (716) 427-0300
Hamilton Hallmark
Long Island
TEL: (516) 434-7400
Rochester
TEL: (716) 475-9130
Ronkonkoma
TEL: (516) 737-0600
Zeus, An Arrow Company
PI. Chester
TEL: (914) 937-7400
TEL: (800) 52·HI·REL
NORTH CAROLINA
Arrow/schweber
Raleigh
TEL: (919) 876-3132
EMC
Charlotte
TEL: (704) 394-6195
Hamilton Hallmark
Raleigh
TEL: (919) 872-0712
Zeus, An Arrow Company
TEL: (407) 333-3055
TEL: (800) 52-HI·REL
OHIO
Alliance Electronics, Inc.
Dayton
TEL: (513) 433-7700
Arrow/schweber
Solon
TEL: (216) 248-3990
Centerville
TEL: (513) 435-5563
EMC
Columbus
TEL: (614) 299-4161

Hamilton Hallmark
Cleveland
TEL: (216) 498-11 00

ArrowJSchweber
Austin
TEL: (512) 835-4180

Colurrilus
TEL: (614) 888-3313

Dallas
TEL: (214) 380-6464
Houston
TEL: (713) 647-6868

Dayton
TEL: (513) 439-6735

Hamilton Hallmark
Austin
TEL: (512) 258-8848
Dallas
TEL: (214) 553-4300

Toledo
TEL: (419) 242-6610
Zeus, An Arrow Company
TEL: (708) 595-9730
TEL: (BOO) 52-HI·REL

Houston
TEL: (713) 781-6100
Wyle Electronics
Austin
TEL: (512) 345-8853

OKLAHOMA
Arrow/schweber
Tulsa
TEL: (918) 252·7537
Hamilton Hallmark
Tulsa
TEL: (918) 254-6110
Zaus, An Arrow Company
TEL: (214) 380-4330
TEL: (800) 52-HI·REL

Houston
TEL: (713) 879-9953
Richardson
TEL: (214) 235-9953
Zeus, An Arrow Company
Carrollton
TEL: (214) 380-4330
TEL: (800) 52·HI·REL

OREGON
AlmaclArrow
Beaverton
TEL: (503) 629-8090

UTAH
ArrowJSchweber
Salt Lake City
TEL: (801) 973-6913

Hamilton Hallmark
Portland
TEL: (503) 526-6200
Wyle Electronics
Beaverton
TEL: (503) 643-7900

Hamilton Hallmark
Salt Lake City
TEL: (801) 266-2022
Wyle Electronics
West Valley City
TEL: (801) 974-9953

Zeus, An Arrow Company
TEL: (408) 629-4789
TEL: (800) 52-HI·REL

Zeus, An Arrow Company
TEL: (408) 629-4789
TEL: (800) 52-HI·REL

PENNSYLVANIA
Arrow/Schweber
Pittsburgh
TEL: (412) 856-9490
Hamilton Hallmark
Pittsburgh
TEL: (BOO) 332-8638
Zeus, An Arrow Company
TEL: (914) 937-7400
TEL: (800) 52-HI·REL

WASHINGTON
AlmaclArrow
Bellevue
TEL: (206) 643-9992
Hamilton Hallmark
Seattle
TEL: (206) 881-6697
Wyle Electronics
Redmond
TEL: (206) 881-1150
Zeus, An Arrow Company
TEL: (408) 629-4789
TEL: (800) 52-HI·REL

TEXAS
Alliance Electronics, Inc.
Carrollton
TEL: (214) 492-6700
Allied Electronics, Inc.
FI. Worth
TEL: (BOO) 433-5700

February 24, 1995
WISCONSIN
Arrow/schweber
Brookfield
TEL: (414) 792-0150
Hamilton Hallmark
Milwaukee
TEL: (414) 780-7200
Wyle Electronics
Waukesha
TEL: (414) 521-9333
Zeus, An Arrow Company
TEL: (708) 250-0500
TEL: (BOO) 52-HI·REL

Harris Semiconductor
Chip Distributors
Chip Supply, Inc.
7725 N. Orange Blossom Trail
Orlando, FL 32810-2696
TEL: (407) 298-7100
FAX: (407) 290-0164
Elmo Semiconductor Corp.
7590 North Glenoaks Blvd.
Burbank, CA 91504-1052
TEL: (818) 768-7400
FAX: (818) 767·7038
Minco Technology Labs, Inc.
1805 Rutherford Lane
Austin, TX 78754
TEL: (512) 834-2022
FAX: (512) 837-6285

Puerto Rican
Authorized Distributor
Hamilton Hallmark
TEL: (809) 731-1110

South American
Authorized Distributor
Graftec Electronic Sales Inc.
One Boca Place, Suite 305 East
2255 Glades Road
Boca Raton, Florida 33431
TEL: (407) 994-0933
FAX: 407 994-5518
BRASIL
Graftec Brasil Llda.
Rua baroneza De ITU 336 • 5
01231-000- Sao Paulo· SP
Brasil
TEL: 55-11-826-5407
FAX: 55-11-826-6526

European Sales Offices and Representatives
European Sales Headquarters
HarrisS.A.
Mercure Center
Rue de la Fusee 100
B-113O Brussels, Belgium
TEL: 32 272421 11
FAX: 32 2 724 2205/ ...09

AUSTRIA
Eurodls Electronics GmbH
Lamezanstrasse 10
A • 1232 Vienna
TEL: 43 1 61062-0
FAX: 43 1 610625

DENMARK
Delco AS
TItangade 15
OK • 2200 Copenhagen N
TEL: 4535821200
FAX: 45 35 8212 05

FINLAND
J. Havullnna " Son
Reinikkalan Kartano
SF· 51200 Kangasnieml
TEL: 358 59 432031
FAX: 358 59 432367

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• Field Application Assistance Available

15-5

European Sales Offices and Representatives (Continued)
Erwin W. Hildebrandt
Nieresch 32
o - 48301 Nottuln-Oarup
TEL: 49 2502 60 65
FAX: 492502 18 89

FRANCE
Hanis Semlconducteurs SARL
• 2-4, Avenue de l'Europe
F - 78941 Velizy Cedex
TEL: 33 1 34 65 40 80 (OISI)
TEL: 33 1 34 65 40 27 (Sales)
FAX: 33 1 39 46 40 54

FINK Handelsvertretung
Laurlnweg,1
85521 Ottobrunn
TEL: 49 89 6 09 70 04
FAX: 49 89 6 09 81 70

o-

GERMANY
Harris Semiconductor GmbH
• Putzbrunnerslrasse 69
0-81739 MOnchen
TEL: 49 89 63813-0
FAX: 49 89 6377891
Harris Semiconductor GmbH
Kieler Strasse 55-59
0-25451 Ouickborn
TEL: 49 4106 50 02-04
FAX: 494106688 50
Harris Semiconductor GmbH
Wegener Strasse, 511
71063 Sindelfingen
TEL: 49 7031 8 69 40
FAX: 49 7031 873849

o-

Hartmut Welte
Hepbacher Sirasse 11 A
o - 88677 Markdorf
TEL: 49 7544 7 25 55
FAX: 49 7544 7 25 55
ISRAEL
Aviv Electronics Ltd
Hayetzira Street, 4 Ind. Zone
IS - 43651 Ra'anana
PO Box 2433
IS - 43100 Ra'anana
TEL: 972 9 983232
FAX: 972 9 916510

Ecker Mlchelstadt GmbH
In den Oorfwiesen 2A
Postfach 33 44
o ·64720Michelstadl
TEL: 49 6061 22 33
FAX: 4960615039

ITALY
Harris SRL
• Viale Fulvlo Tesli, 126
1-20092 Cinlsello Balsamo,
(Milan)
TEL: 39 2 262 07 61
(OiStl & OEM ROSE)
TEL: 39 2 240 95 01
(Oisli & OEM Italy)
FAX: 39 2 262 22 158 (ROSE)
NETHERLANDS
Harris Semiconductor SA
Benelux OEM Sales Office
Kouterslraal 6
NL - 5345 LX Oss
TEL: 31412038561
FAX: 31 412034419
SPAIN
Elcos S. L.
C/Avda. Europa, 30 1 B·A
Spain 28224 Pozuelo de Alarcon
Madrid
TEL: 34 1 352 3052
FAX: 3413521147
TURKEY
EMPA
Besyol Londra Aslal!i
TK - 34630 Selakoy/ Istanbul
TEL: 90 1 599 3050
FAX: 90 1 599 3059

February 24, 1995
UNITED KINGDOM
Harris Semiconductor Ltd
• Riverside Way
Camberley
Surrey GU15 3VO
TEL: 44 276 886 886
FAX: 44 276 662 323
Laser Electronics
Ballynamoney
Greenore
Co. Louth, Ireland
TEL: 353 4273165
FAX: 353 4273518
Complementary
Technologies Ltd
Redgale Road
South Lancashire,lnd. Estate
Ashton·ln-Makerfleld
Wigan, Lancs WN4 80T
TEL: 44 942 274 731
FAX: 44942274732
Stuart Electronics Ltd.
Phoenix House
Bothwell Road
Castlehill, Carluke
Lanarkshire ML8 5UF
TEL: 44 555751566
FAX: 44555751562

European Authorized Distributors
AUSTRIA
Avnet E2000 GmbH
Waidhausenstrasse 19
A -1140Wien
TEL: 43 1 9112847
FAX: 43 1 9113853
EBV Elektronlk
• Oielenbachgasse 35/6
A- 1150 Wien
TEL: 43·222-8941774
FAX: 43-22·8941775
Eurodls Electronics GmbH
Lamezanstrasse 10
A- 1232 Wien
TEL: 43 1 610620
FAX: 43 1 610625
Spoerle Electronic
Heiligenstadter Str. 52
A- 1190 Wien
TEL: 43 1 31872700
FAX: 43 1 3692273
BELGIUM
Diode Spoerle
• Keiberg"
Minervastraat, 14/B2
B·1930 Zaventem
TEL: 32 2 725 46 60
FAX: 32 2 725 45 11

Eurodis Texlm Electronics
• Avenue des Croix de
Guerre 116
B - 1120 Brussels
TEL: 32 2 247 49 69
FAX: 32 2 21581 02
DENMARK
Avnet Nortec
Translormervej, 17
OK - 2730 Herlev
TEL: 45 42 84 2000
FAX: 45 44921552
Ditz Schweitzer
Vallensbaekvej 41
Postboks5
OK - 2605 Brondby
TEL: 45 42 45 30 44
FAX: 45 42 45 92 06
FINLAND
Avnet Nortec
ltalahdenkatu, 1B
SF - 00210 Helsinki
TEL: 358 061 318250
FAX: 358 069 22326

EBV Elektronlk
• Excelsiorlaan 35
B· 1930 Zaventem
TEL: 32 2 716 0010
FAX: 32 2 720 81 52

FRANCE
3D
ZI des Glaises
6/8 rue Ambroise Croizat
F - 91127 Palaiseau
TEL: 33 1 64 47 29 29
FAX: 33 1 64 47 00 84
Arrow Electronlque
73 - 79, Rue des Solets
Silic 585
F - 94663 Rungis Cedex
TEL: 33 1 49 78 49 78
FAX: 33 1 4978 05 96
Avnet EMG France
• 79, Rue Pierre Semard·P.B. 90
F-92320 Chatillon Sous Bagneux
TEL: 33 1 49 65 25 00
FAX: 33 1 49 65 25 39
cel Electronlque
• 12, Allee de la Vierge
Silic577
F - 94653 Rungis
TEL: 33 1 41 80 70 00
FAX: 33 1 46 75 32 07
EBV Elektronlk
Pare Club de la Haute Maison
16, Rue Galilee
Cite Descartes
F • 77420 Champs-sur·Marne
TEL: 33 1 64 88 86 09
FAX: 33 1 64 68 27 67

Bexab
Sinimaenlie 10C
P.O. Box 51
SF • 02630 ESPOO
TEL: 358.0.50 23 200
FAX: 358.0.50 23 294

• Field Application Assistance Available
15-6

Harris Semiconductor
Chip Distributors
Edgetek/RoodTech
Zai De Courtaboeul
Avenue Des Andes
91952 Les Ulis Cedex
TEL: 33 1 64 46 06 50
FAX: 33 1 69 28 43 96
TWX: 600333
Elmo
Z. A. De La Tullerie
B. P. 1077
78204 Mantes-La.Jolie
TEL: 331 3477 16 16
FAX: 33 1 34 77 95 79
TWX: 699737
Hybritech CM (HCM)
7, Avenue Juliot Curie
F - 17027 LA Rochelle Cedex
TEL: 33 46 451270
FAX: 33 46 45 04 44
TWX: 793034
EASTERN COUNTRIES
HEVGmbH
Alexanderplatz 6
0·10178 Berlin
Postfach 90
0- 10173 Berlin
TEL: 4930 243 34 00
FAX: 49 30 243 34 24

February 24, 1995

European Authorized Distributors (Continued)
GERMANY
AvnetlE2000
Stahlgruberring, 12
D - 81829 MOnchen
TEL: 49 89 4511001
FAX: 49 89 45110129
EBV Elektronlk GmbH
• Hans-Pinsel-Strasse 4
o - 85540 Haar-bel-MOnchen
TEL: 49 89 45610-0
FAX: 4989464488
Eurodls Enatschnlk
Electronics GmbH
Pascalkehre, 1
D - 25451 Quickborn
P.B.1240
o - 25443 Quickborn
TEL: 49 4106 701-0
FAX: 49 4106 701268
Indeg Industrle Elektronlk
Emil Kommerling Strasse 5
o - 66954 Pirmasens
Postfach 1563
D - 66924 Pirmasens
TEL: 496331 94065
FAX: 49 633194064
Sasco Semiconductor
GmbH
Hermann-Oberth Strasse 16
o - 85640 Pulzbrunn-beiMOnchen
TEL: 49 89 4611-0
FAX: 49 89 4611-270
Spoerle Electronic
Max-Planck Strasse 1-3
D- 63303 Oreieich-bei-Frankfurt
TEL: 49 6103 304-8
FAX: 49 6106 3 04-201
GREECE
Semicon Co.
104 Aeolou Street
GR - 10564 Athens
TEL: 30 1 32 53 626
FAX: 3013216083
ISRAEL
Aviv Electronics
Hayelzira Street 4, Ind. Zone
IS - 43651 Ra'anana
PO Box 2433
IS - 43100 Ra'anana
TEL: 972 9 983232
FAX: 972 9916510
ITALY
EBV Elektronik
• Via C. Frova, 34
I - 20092 Cinisello Balsamo (MI)
TEL: 39 2 660 17111
FAX: 39 2 66017020
Eureletlronlca
Via Enrico Fermi, 8
1- 20090 Assago (MI)
TEL: 39 2457841
FAX: 39 2 488 02 75
Lasl Elettronlca

Viale Fulvio Testi 280
1- 20126 Milano
TEL: 39 266101370
FAX: 39 266101385

Sliverstar

Viale Fulvio Testi 280
I - 20126 Milano
TEL: 39 266 1251
FAX: 39 2 6610 13 59
NETHERLANDS
• Aurlema Nederland BV
Beatrix de Rijkweg, 8
NL - 5657 EG Eindhoven
TEL: 31 40502602
FAX: 31 40510255
• Diode Spoerle
Collbaan 17
NL - 3439 NG Nieuwegein
TEL: 31 340291234
FAX: 31 340235924
Diode Spoerle
Poslbus 7139
NL - 5605 JC Eindhoven
TEL: 31 40545430
FAX: 31 40535540
EBV Elektronlk
• Planetenbaan, 2
NL - 3606 AK Maarssenbroek
TEL: 31 3465 623 53
FAX: 31 3465642 77
NORWAY
Avnet Nortec
Smedsvingen 4B
Box 123
N - 1364 Hvalstad
TEL: 47 66 84 6210
FAX: 47 66 84 65 45
PORTUGAL
Amitron-Arrow
Quinta Grande, Lote 20
Alfragide
P - 2700 Amadora
TEL: 351.1.4714806
FAX: 351.1.471 0802

SWITZERLAND
Avnet E2000 AG
Boehlralnstrasse 11
CH - 8801 Thalwil
TEL: 41 1 7221330
FAX: 41 1 7221340
Baslx Fur Elaktronlk
Hardturmstrasse 181
CH - 8010 ZOrich
TEL:4112761111
FAX: 41 1 2761234
EBV Elektronlk
• Vorstadtstrasse 37
CH - 8953 Olellkon
TEL: 411 745610
FAX: 41 1 7415110
Eurodls Electronic AG
Bahnstrasse 58160
CH - 8105 Regensdorf
TEL: 41184 33 111
FAX: 41 1 8433910
Fabrlmex Spoerle
Cherstr.4
CH - 8152 Opfikon-Glattbrugg
TEL: 4118746262
FAX: 41 1 8746200
TURKEY
EMPA
Besyol Londra Asfalti
TK - 34630 Sefakoyl Istanbul
TEL: 902125993050
FAX: 90 212 599 3059
UNITED KINGDOM
Arrow-Jermyn Electronic
Vestry Industrial Estate
Sevenoaks
KentTN145EU
TEL: 44 732 743743
FAX: 44 732 451251
AvnetEmg
Jubilee House, Jubilee Road
Letchworth
Hertfordshire SG6 lQH
TEL: 44 482 488500
FAX: 44 482 488567

SPAIN
Amltron-Arrow S.A.
Albasanz, 75
SP - 28037 Madrid
TEL: 34 1 30430 40
FAX:34 1 3272472
EBV Elektronlk
• Calle Maria Tubau, 6
SP - 28049 Madrid
TEL: 34 1 358 86 08
FAX: 34 1 358 85 60

Farnell Electronic
Components
Armley Road, Leeds
West Yorkshire LS12 2QQ
TEL: 44 532790101
FAX: 44 532 833404
Farnell Electronic
Services
Edinburgh Way.
Harlow
Essex CM20 20E
TEL: 44 279 826777
FAX: 44 279 441687

SWEDEN
Avnet Nortec
Englundavagen 7
P.O. Box 1830
S - 171 27 Solna
TEL: 46 8 629 1400
FAX: 46 8 627 0280

Mlcromark Electronics
Boyn Valley Road
Maidenhead
Berkshire SL6 40T
TEL: 44628 76176
FAX: 44 828 783799

Bexab Sweden AB
P.O. Box 523
Kemistvagen, lOA
S - 183 25 Taby
TEL: 46 8 630 88 00
FAX: 46 8 732 70 58

Thame Components
Thame Park Rd.
Thame, Oxfordshire OX9 3UQ
TEL: 44 844 261188
FAX: 44 844 261681

• Field Application Assistance Available
15-7

Harris Semiconductor
Chip Distributors
Ole Technology Ltd.
Corbrook Rd., Chadderton
Lancashire OL9 9S0
TEL: 44 61 626 3827
FAX: 44 61 827 4321
TWX: 668570
Rood Technology
Test House Mill Lane, Alton
Hampshire GU34 2QG
TEL: 44 420 88022
FAX: 44 420 87259
TWX: 21137

South African
Authorized Distributor
TRANSVAAL
Allied Electronic Components
10, Skietlood Street
Isando, Ext. 3, 1600
P.O. Box 69
lsando, 1600
TEL: 27 11 392 3804/• .. 19
FAX: 27 11 9749625
FAX: 27 11 9749683

Asian Pacific
Sales Offices and
Representatives
NORTH ASIA
Sales Headquarters
JAPAN
Harris K.K.
Kojimachi-Nakata Bldg. 4F
5-3-5 Kojimachi
Chiyoda-ku, Tokyo, 102 Japan
TEL: (81) 3-3265-7571
TEL: (81) 3-3265-7572 (Sales)
FAX: (81) 3-3265-7575
SOUTH ASIA
Sales Head~arters
HONGKON

HarTis SemIconductor H.K. Ltd.
13/F Fourseas Building
208-212 Nathan Road
TSimshatsui, Kowloon
TEL: (852) 723-6339
FAX: (852) 739-8946
TLX:78043645
AUSTRALIA
VSI Electronics Ply, Ltd.
Unit C 6-8 Lyon Park Road
North Ryde NSW 2113
TEL: (612) 878-1299
FAX: (612) 878-1266
INDIA
Intersll Private Limited
Plot 54, SEEPZ
MarOllndustrial Area
Andheri (E) Bombay 400 096
TEL: (91) 22-832-3097
FAX: (91) 22-836-6682

I

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February 24, 1995

European Authorized Distributors (Continued)
KOREA
Harris Semiconductor YH
RM #419-1
Korea Air Terminal Bldg.
159-6, Sam Sung-Dong,
Kang Nam-ku, Seoul
135-728, Korea
TEL: 82-2-551-0931/4
FAX: 82-2-551-0930
Inhwa Company, LId.
Room #305
Daegyo Bldg., 56-4,
Wonhyoro - 2GA,
Young San-Ku,
Seoul 140-113, Korea
TEL: 822-703-7231
FAX: 822-703-8711

PHILIPPINES
Intergral Silicon Solution, Inc.
6th Floor Peakson Bldg
1505 Princeton Street
Cor. Shaw Bldg.
Mandauyong
TEL: 632-786652
FAX: 632-786731
SINGAPORE
Harris Semiconductor PIe Lid.
105 Boon Keng Road
#01-18119 Singapore 1233
TEL: (65) 291-0203
FAX: (65) 293-4301
TLX: RS36460 RCASIN

TAIWAN
Harris Semiconductor
Room 1101, No. 142, Sec. 3
Ming Chuan East Road
Taipei, Taiwan
TEL: (886) 2-716-9310
FAX: 886-2-715-3029
TLX: 78525174
Acer Serlek Inc.
3F, No. 135, Sec. 2
Chien Kuo N. Road
Taipei, Taiwan
TEL: (866) 2-501-0055
FAX: (886) 2-501-2521

TECO Enterprise Co., LId.
10FL., No. 292
Min-Sheng W. Rd.
Taipei, Taiwan
TEL: (886) 2-555-9676
FAX: (886) 2-558-6006

Applied Component Tech.
Corp.
8F No. 233-1
Pao-Chia Road
Hsin Tien City, Taipei Hsien,
Taiwan, R.O.C.
TEL: (866) 2 9170858
FAX: 886 29171895

GS Technology PIe, LId.
Block 5073 #02-1656
Ang Mo Kio I ndustrlal Park 2
Singapore 2056
TEL: (65) 483-2920
FAX: (65) 483-2930

KumOh Electric Co., LId.
203-1, Jangsa-Dong,
Chongro-ku, Seoul
TEL: 822-279-3614
FAX: 822-272-6496

Galaxy Far East Corporation
8F-6, No. 390, Sec. 1
Fu Hsing South Road
Taipei, Taiwan
TEL: (886) 2-705-7266
FAX: 886-2-708-7901

Asian Pacific Authorized Distributors
AUSTRALIA
VSI Electronics Ply, LId.
Unit C 6-8 Lyon Park Road
North Ryde NSW 2113
TEL: (612) 878-1299
FAX: (612) 878-1266

JAPAN
Hakuto Co., LId.
1-1-13 Shinjuku Shinjuku-ku
Tokyo 160
TEL: 81-3-3355-7615
FAX: 81-3-3355-7680

CHINA
Means Come LId.
Room 1007, Harbour Centre
8 Hok Cheung Street
Hung Hom, Kowloon
TEL: (852) 334-8188
FAX: (852) 334-8649
Sunnlce Electronics Co., LId.
Flat F, 51F, Everest Ind. Ctr.
396 Kwun Tong Road
Kowloon,
TEL: (852) 790-8073
FAX: (852) 783-5477
HONG KONG
Array Electronics Limited
241F., Wyler Centre
Phase 2
200 Tai Lin Pai Road
Kwai Chung
New Territories, H.K.
TEL: (852) 418-3700
FAX: (852) 481-5872
Inchcape Industrial
1OfF, Tower 2, Metroplaza
223 Hing Fong Road
Kwai Fong
New Territories
TEL: (852) 410-6555
FAX: (852) 401-2497
Kingly International Co., LId.
Flat 03, 16/F, Block A,
Hi-Tech Ind. Centre
5-12 Pak Tin Par St.,
TsuenWan
New Territories, H.K.
TEL: (852) 499-3109
FAX: (852) 417-0961

KOREA
KumOh Electric Co., LId.
203-1, Jangsa-Dong,
Chongro-ku, SeOUl
TEL: 822-279-3614
FAX: 822-272-6496

Jepico Corp.
Shinjuku Daiichi Seimei Bidg.
2-7-1, Nishi-Shinjuku
Shinjuku-ku, Tokyo 163
TEL: 03-3348-0611
FAX: 03-3348-0623
Macnica Inc.
Hakusan High Tech Park
1-22-2, Hakusan
Midori-ku, Yokohama-shi,
Kanagawa 226
TEL: 045-939-6116
FAX: 045-939-6117
Micron, Inc.
DJK Kouenji Bldg. 5F
4-26-16, Kouenji-Minami
Suginami-Ku, Tokyo 166
TEL: 03-3317-9911
FAX: 03-3317-9917
Okura Electronics Co., Ltd.
Okura Shoji Bldg.
2-3-6, Ginza Chuo-ku,
Tokyo 104
TEL: 03-3564-6871
FAX: 03-3564-6870
Takachlho Kohekl Co., LId.
1-2-8, Yotsuya
Shinjuku-ku, Tokyo 160
TEL: 03-3355-6696
FAX: 03-3357-5034

Inhwa Company, LId.
Room #305
Daegyo Bldg., 56-4,
Wonhyoro - 2GA,
Young San-Ku,
Seoul 140-113, Korea
TEL: 822-703-7231
FAX: 822-703-8711
NEW ZEALAND
Components and
Instrumentstlon NZ, Lid.
19 Pretoria Street
Lower Hull
P.O. Box 38-099
Wellington
TEL: (64) 4-566-3222
FAX: (64) 4-566-2111
PHILIPPINES
Intergral Silicon Solution, Inc.
6th Floor Peakson Bldg
1505 Princeton Street
Cor. Shaw Bldg.
Mandauyong
TEL: 632-786652
FAX: 632-786731

Device Electronics PIe, LId.
605B MacPherson Road
04-12 Citimac Ind. Complex
Singapore 1336
TEL: (65) 288-6455
FAX: (65) 287-9197
Willas - Array PIe, LId.
40 Jalan Pemimpin
#04-03B Tat Ann Building
Singapore 2057
TEL: (65) 353-3655
FAX: (65) 353-6153
TAIWAN
Acer Sertek Inc.
3F, No. 135, Sec. 2
Chien Kuo N. Road
Taipei, Taiwan
TEL: (886) 2-501-0055
FAX: (886) 2-501-2521
Applied Component
Technology Corp.
8F No. 233-1 Pao-Chial Road
Hsin Tien City, Taipei Hsein,
Taiwan, R.O.C.
TEL: (02) 9170858
FAX: (02) 9171895
Galaxy Far East Corporation
8F-6, No. 390, Sec. 1
Fu Hsing South Road
Taipei, Taiwan
TEL: (886) 2-705-7266
FAX: 886-2-708-7901

mHARRIS
W

SINGAPORE
B.B.S Electronics Pte, Ltd.
1 Genllng Link
#05-03 Perfect Indust. Bldg.
Singapore 1334
TEL: (65) 748-8400
FAX: (65) 748-8466

SEMICONDUCTOR

• Field Application Assistance Available
15-8

TECO Enterprise Co., LId.

1OFL., No. 292, Mirt-Sheng W. Rd.
Taipei, Taiwan
TEL: (886) 2-555-9676
FAX: (886) 2-558-6006

16
INDEX
AC Bias Reliability ............................. 8-12
AC-DC Difference .............................. 7-4
Across-The-Line Components .................•.. 7-12
Accelerated Humidity Life ....................... 8-19
Accelerated Storage Life ........................ 8-19
Accelerated Testing .................... 8-11 thru 8-14
AC Power Lines, Transients ...................... 1-5

Capacitance, Varistor. ................... 2-11, 3-4, 3-9
Carbon Blocks ................................. 5-5
Central Office .................................. 5-7
Ceramic Structure ....................... 3-1 thru 3-3
Characteristic Measurement ..................... 7-12
Characteristics, Electrical ................. 3-8 thru 3-10
Characteristics Table ............................ 4-1
Circuit Models, Varistors ..................... 3-8, 3-9

Activation Energy .............................. 8-11
Aging ....................................... 2-10
Alpha .................................... 2-5,3-10
Alternator Field Decay ........................ 1-7,6-2
ANSI. ....................................... 7-15
ANSI Standard .............. 1-11,1-16, 4-26, 7-15, 7-16
AnswerFAX .................................. 14-1

Clamp Ratio ................................... 4-6
Clamp Voltage Measurements ..................... 7-5
Clamping ..................................... 2-1
Clamping Voltage ............................... 4-6
Clearing Time ................................. 4-12
CMOS Protection ............................. 11-16
Comparison of Suppressors ....................... 2-5

Applications, Automotive .................... 6-1, 12-54
Applications, Crowbar .......................... 4-25
Application Examples......... 4-12 thru 4-26, 5-4 thru 5-7
............. 6-1 thru 6-6, 10-5 thru 10-8, 12-3 thru 12-54
Applications, Motor Control ...................... 4-13
Applications, Motor Protection ............ 4-21 thru 4-25
Applications, Nois~ Reduction .................... 4-18

Connector Pin Varistor .................... 2-14,12-32
Conservation, Power ............................ 1-9
Construction, Varistor ............................ 3-5
Contacts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8
Contact Arcing ........................ 4-16 thru 4-18
Contact Bounce . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
Contact Bouncing .............................. 4-17

Applications Telecom ........................... 5-11
Applications, Power Supply ................. .4-12, 4-13
Applications, Relays. . . . . . . . .. . . . . . . . . .. 4-16 thru 4-18
Arcing, Contact ............................... 4-16
Arcing, Switch ................................. 1-3
Array Protection .......................... 11-6. 11-11
Arrhenius Models .............................. 8-13

Contact Welding ................................ 1-8
Continuous Power Dissipation .................... 7-11
Continuous Ratings ............................. 7-9
Creepage Specifications ......................... 1-8
Crowbar, Power Supply ......................... 4-25
Crowbar Type Suppressors ................... 2-1, 2-4
Current, Derating ............................... 4-5
Current, Peak Rating ............................ 4-4

Assurance Tests ............................... 7-9
Asymmetrical Polarity ........................... 7-4
Automotive Central Suppressor .................... 6-3
Automotive Electrical System ..................... 6-1
Automotive Ignition ............................. 6-5
Automotive Test Waveforms ...................... 6-3
Automotive Transients ........................ 1-7,6-1
Avalanche Diodes .............................. 2-4

Date Codes ................................. 12-52
DC Bias ..................................... 8-14
DC Power Life ....•........................... 8-15
DC Standby Current. ............................ 7-7
Degradation, Semiconductor ...................... 1-7
D.E.S.C. Approved Parts ................ 13-2 thru 13-4
Detection of Transients .................... 1-10,7-12

Branch Circuits................................ 1-15
Break-In Stabilization ............................ 7-4
Building Locations ............................. 1-15
Buried Cable ...............................5-1, 5-2

Detector, R.F. Noise ............................ 4-18
Delay Time, Gas Tube ........................... 2-4
Derating Curves ................................ 4-5
Dielectric Breakdown ............................ 1-8
Disc Diameter .................................. 3-5
Disc Thickness ................................. 3-3
Dissipation Factor............................... 7-8
DOX ..................................... 8-4, 8-8
Dynamic Resistance ...................... , 3-10,3-11

Cable Plant ................................... 5-1
Cable Shield .................................. 5-1
Cable, Suspended .............................. 5-2
Cable Transients ............................... 5-2
Capacitor Clamping ........................... 4-17
Capacitance, Stray ............................. 1-3

16-1

Electromechanical Contacts ................•.. 1-2, 1-3
Electromechanical Switching ................. '" .• 1-8
Electronic Ignition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-5
Energy Conservation. . . . • . . • • . . . . . . . . . . . • . . . . . .. 1-9
Energy Calculations............................• 4-3
Energy Inductive ............................... 1-1
Energy, Pulse ................................. 8-16

Induced Transients ............................. 5-4
Inductance, Leads. . . . . . . . . . . . . . . . . .. 3-11,7-5, 12-52
Induction Motor, Stored Energy ............... 4-22, 4-23
Inductive Load Switching. . • . . . . . . . • . . . . . . . .. 1-8, 4-16
Inductive Loads, Transistor Switching .............. 4-20
Inductive Switching ...•................... ; .... 4-16
Inrush Current ........................... "...... 1-1

Energy Pulse Testing ......•.....•............. 7-10
Energy Rating ....•.......•........ 4-3, 7-9, 7-10, 8-18
Energy, Stored...............•........ 1-2, 4"22, 4-23
Energy Waveshape Constants ...............•.... 4-3
Energy Withstand .. . . . . . . . . . . . . . . . . . . . . . . . . . .. 8-18
Energy, 60Hz Surge Capability .......••.......... 8-18
Encapsulation ....................•.•.......... 3-5

Instrumentation, Transient Detection .......... 7-12,7-13
Insulation ..................................... 1-8
ISO 9000 .....•........................... 8-2, 8-8
121 •••••••••••••••••••••••••.•.••••••••••••••• 4-9

Engine Shutdown ...............•..•........... 1-7
Engineering Evaluation .......................... 7-1
Environmental Testing .......................... 8-19
Environmental Reliability. . . . . . . . . . . . . . . . . • . . . . .. 8-20
Epoxy........................................ 3-5
Equipment, Test .............................. 7-13
Equivalent Circuit. ...............•...... 3-9 thru 3-11
Failure Definition .........................•.... 8-14
Failure, Insulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-8
Failure Modes ........................ 2-11, 4-8, 8-18
Failure, Semiconductor ........................•. 1-8
Fault Conditions. . . . . • . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
FCC Standard ............. : ............. 7-15,7-16
F.M.E.A.•..•.................................. 8-8
Field Decay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-3
Field Failures ................................. 8-10
Field Maintenance .............................. 7-2
Field Testing .................................. 7-2
Filters ....•................................... 2-2
Fire Retardant . . . . . . . . . . . . . . . . . . . . . . . . . .. 7-12, 8-18
Flame Test .............................. 7-12,8-19
Flashover. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-8
Follow Current. ..................••............ 2-4
Fuse Clearing ................... , ............ 4-10
Fuse Selection ................................. 4-8
Fusing, Varistor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8
Gas Tubes .............................. 2-4, 12-46
Grain Structure . • . . . . . . . . . . . . . . . . . . . . • . . . .. 3-1, 3-2
Ground Currents ........... " .................. 5-1
Ground Potential Rise ..•........................ 5-4
Harris Varistor Properties . . . . . . . . . . . . . . . .. 3-1 thru 3-3
Heavy Metals .......................•.....•... 12-52
High Reliability Testing ......................... 13-1
Humidity Ufe ........................•........ 8-20
Hybrid Protection .........................•... 2-11
Idle Power ...••........................•...... 2-7
IEEE Standard ..................... " .... 3-13,7-15
IEC Standard. . . . . . . . . . . . . . . . . . . . • . . . . . . .. 1-9, 1-11
Ignition, Electronic ...........................••. 6-5
Impedance, Source .•............... " .... 7-16,7-17
Impulse Generators ............................ 7-12
Incoming Inspection........................ ; ; .•. 7-'J,

16-2

Jump Starts ............................... 1-7,6-1
Junction, Grain Boundry ..................... 3-2, 3-3
Kettering Ignition ............................... 6-5
Lead Length •.................................. 7-6
Leakage Current ...........................•... 3-8
Leakage Region .•................•........ 3-9,3-10
Ufe, DC Power ................................ 8-15
Ufe, Humidity ..............................•.. 8-20
Ufe, Storage .................................. 8-20
Ufe Testing .........................•. 7-9 thru 7-11
Ufetime Current Rating ......................... 4-45
Ughtning ............................ 4-9,5-8,10-2
Ughtning Strikes ........................ , ...... 5-1
Lightning Transients .........•................... 5-4
Load Dump. . . . . . . . . . • . . . . . . . . . . . .. 1-7,6-1 thru 6-4
Load Une .......................... 4-4, 4-6, 4-13
Location Categories .........•.................. 1-15
Loop Area ................•................... 7-6
Low Profile Varistor ...•........................ 2-18
MA Outline .............•....•..............•.. 3-7
Magnetizing Currents ....•... " ...............•. 4-15
Manufacturing Sequence .•....................•.. 3-5
Matching for Paralleling ......................... 4-12
Measurement, Capacitance ....................... 7-8
Measurement, Clamp Voltage ..................... 7-5
Measurement of Characteristics •...............•.. 7-2
Mechanical Reliability and Integrity ................. 8-19
Mechanical Shock .•........•.................. 8-19
Mechanical and Environmental Testing ............. 8-19
Measuring Transients ..................... 7-12,7-14
Metal Oxide Properties ..•..•..... . . . . . . . 2-5, 3-2, 3-3
Military QPL ......................... 13-2 thru 13-4
Model, Equivalent Circuit Varistors ......... 3-9 thru 3-11
Model Number ..•........•..................... 4-2
Motor Protection ..............•..............•. 4-21
Mutual Coupling ............................... 4-16
Noise Contacts .........•....................... 1-9
Noise Generation ............•.................. 1-9
Noise Suppression .....................•....... 4-18
Non-Linear Resistors .•.......................•.. 2-5
Operation, Theory ..•........................... 3-3
Overshoot Effect .............•..... 3-12, 7-5 thru 7-7
Package Identification . . . • . . . . . . . . . . . . . . . . .. 3-6, 10-2
Package Material Expulsion ...................... 8-19
Package Rupture ............................•. 8-19

Paralleling Varistors ............................ 4-11
Peak Current Rating . . . . . . . . . . . . . . . . . . . . . . .. 4-4, 7-9
PFAST ................................. 8-5 thru 8-7
Phase Connections. . . . . . . . . . . . . . . . . . . . . . . .. 9-8, 9-9
PN Junction ................................ 3-1, 3-3
Power Circuits (AC) ............................ 1-12
Power Contact. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-4
Power Cross . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Derating Curve ..........................
Power Dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power, Follow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Induction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Line (AC) Transients ......................
Power Savings.................................

5-4
4-5
4-5
2-4
5-4
1-5
1-9

Power Supply Crowbar. . . . . . . . . . . . . . . . . . . . . . . . . 4-25
Power Supply Protection ........................ 4-12
Power, Standby ................................ 2-7
Product Series, Varistor................. 9-11 thru 9-105
Product Series, SURGECTOR ........... 10-3 thru 10-20
Primary Protection ............................. 5-5
Product Family Guide ........................... 4-7
Product Ratings and Characteristics ....... 9-11 thru 9-105
Product Qualification. . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-1
Proof Tests .................................. 2-12
Pulse Current Testing ........................... 7-5
Pulse Current Waveform .................... 3-14, 3-15
Pulse Energy .......................... 8-16 thru 8-18
Pulse Rating ......................... 4-4, 4-20, 4-21
Pulse Rating Curves ................... 9-11 thru 9-105
Pulse Test Stability ............................ 8-17
Pulse Withstand. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-10
Punch-Through . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-16
Quality Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1
Questions, First Order. . . . . . . . . . . . . . . . . . . . . . . .. 12-50
RA Series Varistors ............................ 9-87
Radiation Hardness ................... 8-21, 13-7, 13-8
Random Transients ............................. 1-4
Rate Effect. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-11
Rate of Rise ................................... 1-9
Rating, Assurance .............................. 7-9
Ratings, Current vs. Temperature .................. 4-4
Rating, Energy ............................. 4-3, 8-18
Rating, Peak Current. ........................... 4-4
Rating, Power Dissipation ........................ 7-9
Rating Table .................................. 4-1
RC Network .................................. 4-17
RC Network, Snubber ........................... 2-2
REA Standard ................................ 7-15
Relay ........................................ 1-3
Relay Switching .............................. 4-16
Reliability. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-1
Reliability, AC Bias ............................ 8-12
Reliability, DC Bias . . . . . . . . . . . . . . . . . . . . . . . . . . .. 8-14
Reliability, DC Power Tests ...................... 8-14
Reliability, Environmental ....................... 8-20

16-3

Reliability, Mechanical .......................... 8-19
Reliability Model, DC Power Life .................. 8-16
Reliability Prediction ............................ 8-12
Resistance, Dynamic ........................... 3-11
Resistance, Static ............................. 3-11
Response Time ............................2-9, 3-11
Restrike ...................................... 1-3
RFI Filter .................................... 4-13
SAE Test Circuits ............................... 6-3
Secondary Protection ........................... 5-6
Selection Guide ............................ 4-7, 4-26
Selenium Suppressors ........................... 2-4
Semiconductor Degradation ...................... 1-7
Semiconductors, Transient Effects ................. 1-7
Seriesing Varistors ............................. 4-11
Service Entrance .............................. 1-15
Shielding, Physical. ............................ 8-14
Shock Testing ................................ 8-19
Short Circuit, Device ........................... 8-16
Signal Line Protection .......................... 11-6
Silicon Carbide ................................ 2-5
Solderability ....................... 12-3, 12-15, 13-6
Solderability, Reliability ......................... 8-19
Source Impedance ..................... 2-2,7-16,7-17
Spark Gaps ............................ 2-4, 2-6, 2-8
SPC ......................................8-8, 8-9
Speed of Response ................... 2-9,3-12, 12-52
SP720/SP721 Tech Brief. ...................... 11-16
Stability, Long-Term ............................ 8-16
Stability, Pulse Test ............................ 8-16
Standards, Transients .......................... 1-11
Standby Power ................................ 2-7
Starting Currents .............................. 4-24
Static Resistance, Varistor. ...................... 3-11
Storage Life . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-13
Storage Oscilloscope .......................... 7-14
Storage Reliability ............................. 8-19
Stored Energy. . . . . . . . . . . . . . . . . . . . . . . . .. 1-1 thru 1-4
Stored Energy, Motor .......................... 4-23
Stress Levels ................................ 8-16
Suppression Devices ............................ 2-1
Suppressors, Avalanche Diodes ................... 2-4
Suppressors Comparison ........................ 2-6
Suppressor, Selenium ........................... 2-4
Suppressor, Zener ............................. 2-4
Surface Mount Varistors ................... 2-17,12-5
Surge Energy (60Hz) Capability .................. 8-18
Surge Impedances .............................. 5-2
Surge Testing ................................. 7-10
Surge Withstand Capability (SWC) ................. 1-6
Surge Withstand Capability Standard .............. 7-16
SURGECTOR Applications .............. 5-11 thru 5-14
SURGECTOR Nomenclature, Packages,
and Shipping ............................... 5-10
SURGECTOR Operation ......................... 5-8
SURGECTOR Performance Characteristics .......... 5-9
SURGECTOR Specifications .................... 10-2
SURGECTOR Directory......................... 10-1

><
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o
~

Suspended Cable .............................. 5-2
Switch Arcing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
Switching, Contacts ............................ 4-16
Switching, Inductive loads ...................... 4-16
Symbols, Varistor ............................. 3-13
Telecommunications ............................ 5-1
Telecommunication Line Transients ............... , 1-7
Telephone Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-7
Telephone Protection .......................... 5-12
Temperature Coefficient . . . . . . . . . . . . . . . . . . . . . . . . 3-10
Temperature Dependence........................ 7-7
Temperature Derating ........................... 4-4
Temperature Effects ............................ 3-9
Terminal Strength ............................. 8-19
Terminology ........... , ...................... 3-13
Test Equipment ............................. 7-13,14
Testing ......... " .... , ...................... 2-12
Testing, Clamp Voltage .......................... 7-5
Testing, Current Surge ......................... 7-12
Testing,
Testing,
Testing,
Testing,
Testing,
Testing,
Testing,

DC Standby Current ................ " ... 7-7
Environmental ......................... 8-19
Field .... " ............................ 7-2
Mechanical............................ 13-6
Pulse Energy .......................... 7-10
Transient Power........................ 7-11
Transients . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1-11

Testing, Varistors .............................. 7-1
Test Objectives ................................ 7-1
Test Waves .............................. " .. 7-14
Test Waveform ............................... 3-15
Thermal Runaway ............... " ............ 4-5,8
Thermal Shock ............................... 8-19
Thevein Equivalent Circuit. ........... " .......... 4-4
Tip and Ring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-6
Training ...................................... 8-8
Transient Control level (TCl) .................. 1-6,7-1
Transmission Lines ............................. 5-1
Transformer ............................... 1-2,4-14
Transformer, Magnetizing Current ................. 1-2
Transients, AC Power Lines . . . . . . . . . . . . . . . . . . . . .. 1-5
Transients, Automobile .......................... 1-7
Transients, Cable .............................. 5-1
Transient Detection ........................... 1-10
Transient Effects ............................... 1-7
Transient Environment .................. 1-12 thru 1-15
Transient Measurements ........................ 7-12
Transient Power .............................. 7-10

16-4

Transient Standards ............................ 1-11
Transient Testing .............................. 1-11
Transients, Random .......................... " . 1-4
Transients, Repeatable .......................... 1-1
Transients, Telecommunication .................... 1-7
Tubular Varistor .............................. 2-14
TV Receiver ................................. 4-13
Ul Flamability ................................. 9-4
Ul Recognition ...................... 5-11, 7-12,8-19
Ul Standards .............................7-12, 8-19
Uptum Region ................................. 3-8
Varistor....................................... 2-4
Varistor Capacitance .........................3-4, 3-9
Varistor Circuit Model. ........................... 3-9
Varistor Construction ............................ 3-7
Varistor Failure Mode ........................... 2-11
Varistor Fusing ................................. 4-8
Varistor Matching .............................. 4-11
Varistors, Metal Oxide ........................2-5, 3-1
Varistor Rating ................................. 7-9
Varistor Reliability .............................. 8-1
Varistor Selection ............. 4-1, 4-7, 4-14, 4-18, 4-26
Varistor Sheilding .............................. 8-14
Varistor Specifications ................. 9-11 thru 9,105
Varistor Stability .............................. 8-16
Varistor Symbols ........................... 3-13, 15
Varistor Terminology ........................... 3-13
Varistor Terms ................................ 3-13
Varistor Test System ........................... 7-13
Varistor Testing ................................ 7-1
Varistor Voltage Measurement .................... 7-2
Varistor Voltage Ratings ........................ 4-24
Vibration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-19
Vibration Fatigue .............................. 13-6
Vibration, Variable ............................. 13-6
Volt-Ampere Characteristics ...................2-1,2-5
Voltage Clamping ............................... 4-6
Voltage Dependent Device ...................... 3-11
Voltage Rating Table ............................ 4-1
Waveform, Test ............................... 3-15
Zener Suppressors ........................2-4, 12-44
Zinc Oxide ................................... 3-11

.. .

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