AX995 Datasheet. Www.s Manuals.com. R1.1 Axelite

User Manual: Datasheets AX995, AX995SA.

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AX995

1.6X Linear Fan Driver with VO Fully On
Control


GENERAL DESCRIPTION
The AX995 is a low dropout linear regulator which is designed to power a DC fan
and delivers up to 600mA output current. The output voltage follows the 1.6 times of
VSET voltage and typical dropout voltage is only 150mV (typical) at 600mA output
current. The VSET voltage must be larger than 1V to guarantee V O 1.6 times of VSET. A

FON pin turns VO output fully on when given low. The features of current limit (with fold
back current) and over temperature protection protect the device against current
over-loads and over temperature. The AX995 is available in a SOP-8 package.




FEATURES
-

Low Dropout Voltage: 150mV@0.6A
VO Follows 1.6 times of VSET

-

FON Pin to Turn VO Fully On
Stable with Low ESR Ceramic Capacitors
Current-Limit and Thermal Shutdown Protection
SOP-8 Pb-Free Package

BLOCK DIAGRAM

VO

VIN
Current Limit and
Short Protection
- +

Error
Amp

Thermal
Shutdown
FON

VO Fully On
Logic

GND
VSET

1/8
Axelite Confidential Materials, do not copy or distribute without written consent.
Rev.1.1 Aug.25, 2010

AX995



PIN ASSIGNMENT

AX995

The package of AX995 is SOP-8L; the pin assignment is given by:
Name
Description
( Top View )
GND GND pin
VIN IC power supply pin
FON 1
8 GND
Output Pin. Its voltage is 1.6 times of
VO
VSET
7 GND
VIN 2
This pin sets the output voltage. Its
6 GND VSET voltage must be larger than 1V to
VO 3
guarantee VO 1.6 times of VSET
5 GND
VSET 4
FON Input. Pulling this pin below 0.4V
FON
turns
the regulator fully on. Internally
SOP-8L
pulled high.


ORDER/MARKING INFORMATION
Order Information

AX995 X X
Package Type
S : SOP-8L



Top Marking

9 9 5
AX
Y Y WW X

Logo

Part number
ID code:internal

Packing

WW: 01~52
Year: 10=2010
11=2011

Blank : Tube
A : Taping

ABSOLUTE MAXIMUM RATINGS (at TA=25°C)
Characteristics

Symbol

Rating

Unit

VIN Supply Voltage

VIN

-0.3 to 6.5

V

FON Input Voltage

VFON

-0.3 to VIN

V

VSET Voltage

VSET

-0.3 to VIN

V

Power Dissipation

PD

Internally limited

W

Storage Temperature Range

TST

-65 to +150

°C

Junction Temperature Range

TJ

-40 to 125

°C

Operating Temperature Range
Thermal Resistance from Junction to case

TOP
θJC

-40 to +85
20

°C
°C/W

Thermal Resistance from Junction to ambient

θJA

60

°C/W

Note: θJA is measured with the PCB copper area approximately 1.5

in2 (Multi-layer)

2/8
Axelite Confidential Materials, do not copy or distribute without written consent.
Rev.1.1 Aug.25, 2010

AX995



ELECTRICAL CHARACTERISTICS
(VSET=2V, VIN=5V, IOUT= 0.5A, CIN=COUT=2.2uF, TA=25°C unless otherwise specified)
Characteristics

Symbol

VIN Supply Voltage Range

VIN

Quiescent Current

ICCQ

Output Voltage/VSET Voltage

VO/VSET

Line Regulation
Load Regulation
Output Resistance

RDS(ON)

Current Limit

ILimt

Short Circuit Current

IShort

Minimum VSET Voltage
VSET Pin Current

FON Pin Logic Threshold Voltage

Conditions
VO=5V, No Load
VIN=5.5V,
VSET=1V~3.2V
VIN=4.5V to 5.5V
IOUT =10mA ~ 0.6A
IOUT=0.6A,
VSET=3.4V

4.5

-

5.5

V

-

70

-

uA

1.552 1.6 1.648 V/V
-

0.2

0.5

%

-

0.2

0.5

%

-

240 320

mΩ

-

1

-

A

-

0.5

-

A

VSET

-

1

-

V

ISET

-

80 200

Vo<0.6V

nA

VFON-H Normal Operating

2.0

-

-

VFON-L Regulator Fully On

-

-

0.8

-

1

5

uA

-

140

-

°C

-

30

-

°C

FON Pin Bias Current

IFON

Thermal shutdown Temp

TSD

FON =0V

Thermal Shutdown Hysteresis


Min Typ Max Units

V

APPLICATION CIRCUIT
U1
VIN=5V

2
VSET
C1

2.2uF

FON

4
1

VIN

VO

Vo=1.6 X VSET

3

VSET
FON

GND

5,6,7,8

C2
2.2uF

FAN

AX995

3/8
Axelite Confidential Materials, do not copy or distribute without written consent.
Rev.1.1 Aug.25, 2010

AX995



FUNCTION DESCRIPTIONS
Output Voltage Regulation
The Output Voltage is set by VSET voltage. VO output voltage follows the 1.6
times of VSET voltage until it reaches VIN voltage.
Fully-On Control
If the FON pin logic level smaller than 0.8V, the output voltage can be
promoted near to VIN voltage. Otherwise, VOUT is normal operating by FON larger
than 2.0V.
Current-Limit
The AX995 monitors the current via the output PMOS and limits the maximum
current to prevent load and AX995 from damages during overload or short circuit
conditions.
Short Current Protection
When the output voltage drops below 0.6V (typical), which is caused by over load
or short circuit, the fold back current limit circuitry limits the output current to 500mA.
The fold back current limit is used to reduce the power dissipation during short circuit
condition.
Thermal Shutdown
A thermal shutdown circuit limits the junction temperature of AX995. When the
junction temperature exceeds +140°C, a thermal sensor turns off the output PMOS,
allowing the device to cool down. The regulator regulates the output again through
initiation of a new soft-start cycle after the junction temperature cools by 30°C, resulting
in a pulsed output during continuous thermal overload conditions.

4/8
Axelite Confidential Materials, do not copy or distribute without written consent.
Rev.1.1 Aug.25, 2010

AX995



APPLICATION INFORMATION
Capacitor Selection
Normally, use a 2.2µF capacitor on the input and a 2.2µF capacitor on the output
of the AX995. In order to insure the circuit stability, the proper output capacitor value
should be larger than 1uF. With X5R and X7R dielectrics, 2.2uF is sufficient at all
operating temperatures.
Thermal Considerations
The AX995 series can deliver a current of up to 500mA over the full operating
junction temperature range. However, the maximum output current must be dated at
higher ambient temperature to ensure the junction temperature does not exceed 125°C.
With all possible conditions, the junction temperature must be within the range specified
under operating conditions. Power dissipation can be calculated based on the output
current and the voltage drop across regulator.
PD = (VIN - VO) IO
The final operating junction temperature for any set of conditions can be
estimated by the following thermal equation:
PD (MAX) = (TJ (MAX) - TA) / θJA
Where TJ (MAX) is the maximum junction temperature of the die (125°C) and TA is
the maximum ambient temperature. The junction to ambient thermal resistance (θJA) for
SOP-8L package at recommended minimum footprint is 60°C/W. Visit our website in
which “Recommended Footprints for Soldering Surface Mount Packages” for detail.
PCB Layout
1. Please place the input capacitors close to the V IN
2. Ceramic capacitors for load must be placed near the load as close as possible
3. To place AX995 and output capacitors near the load is good for performance.
4. Large current paths that VIN and Output lines must have wide tracks.
5. GND connect large copper area can reduced IC temperature.

5/8
Axelite Confidential Materials, do not copy or distribute without written consent.
Rev.1.1 Aug.25, 2010

AX995

TYPICAL CHARACTERISTICS



VSET VS ICCQ

ICCQ (uA)

ICCQ (uA)

VIN VS ICCQ
200
180
160
140
120
100
80
60
40
20
0

IOUT=0A

3

3.5

4

4.5
5
VIN (V)

5.5

200
180
160
140
120
100
80
60
40
20
0
0

6

4

VOUT (V)

VOUT (V)

5

3
2
1

IOUT=100A
VIN=5.5

0
1

1.5

2

2.5

1

1.5

3

3.5

4

4

0℃

25℃ 50℃ 75℃ 100℃ 125℃

Temperaute VS FON Voltage

FON Voltage (V)

Output Resistance (m Ω)

3.5

VSET=1V
IOUT=200mA
-40℃ -25℃

Temperaute VS Output Resistance

VIN=5V
VSET=3.5V
IOUT=500mA
25℃ 50℃

3

Temperature(℃)

500
450
400
350
300
250
200
150
100
50
0
0℃

2.5

1.70
1.68
1.66
1.64
1.62
1.60
1.58
1.56
1.54
1.52
1.50

VSET (V)

-40℃ -25℃

2

Temperaute VS VOUT

VSET VS VOUT

0.5

0.5

VSET (V)

6

0

IOUT=0A

75℃ 100℃ 125℃

Temperature(℃)

2
1.8
1.6
1.4
1.2
1
0.8
0.6
0.4
0.2
0

VFON-H

VFON-L

-40℃ -25℃

0℃

25℃

50℃

75℃ 100℃ 125℃

Temperature(℃)

6/8
Axelite Confidential Materials, do not copy or distribute without written consent.
Rev.1.1 Aug.25, 2010

AX995



TYPICAL CHARACTERISTICS (CONTINUOUS)
Power ON

Power ON

Fully-On

Fully-On(VIN Drop)

Load Transient

Load Transient (VIN Drop)

7/8
Axelite Confidential Materials, do not copy or distribute without written consent.
Rev.1.1 Aug.25, 2010

AX995

H

PACKAGE OUTLINES

E



θ
L
DETAIL A

b
D

e

y

A1

C

A

A2

7 (4X)

Dimensions in Millimeters
Min.
Nom.
Max.
A
1.75
A1
0.1
0.25
A2
1.25
C
0.1
0.2
0.25
D
4.7
4.9
5.1
E
3.7
3.9
4.1
H
5.8
6
6.2
L
0.4
1.27
b
0.31
0.41
0.51
e
1.27 BSC
y
0.1
O
θ
0
8O
Mold flash shall not exceed 0.25mm per side
JEDEC outline: MS-012 AA
Symbol

DETAIL A

Dimensions in Inches
Min.
Nom.
Max.
0.069
0.04
0.1
0.049
0.0075
0.008
0.01
0.185
0.193
0.2
0.146
0.154
0.161
0.228
0.236
0.244
0.015
0.05
0.012
0.016
0.02
0.050 BSC
0.004
O
0
8O

8/8
Axelite Confidential Materials, do not copy or distribute without written consent.
Rev.1.1 Aug.25, 2010

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