Telit Communications S p A LE920NA LE920-NAG User Manual HW User Guide
Telit Communications S.p.A. LE920-NAG HW User Guide
User manual
| Download: |  |
| Mirror Download [FCC.gov] | |
| Document ID | 2094693 |
| Application ID | Z9ODrfw3N1iMmepJhxFdZg== |
| Document Description | User manual |
| Short Term Confidential | No |
| Permanent Confidential | No |
| Supercede | No |
| Document Type | User Manual |
| Display Format | Adobe Acrobat PDF - pdf |
| Filesize | 156.02kB (1950294 bits) |
| Date Submitted | 2013-10-18 00:00:00 |
| Date Available | 2014-04-27 00:00:00 |
| Creation Date | 2013-09-24 11:32:08 |
| Producing Software | Acrobat Distiller 9.3.3 (Windows) |
| Document Lastmod | 2013-09-24 11:32:08 |
| Document Title | HW User Guide Template |
| Document Creator | Acrobat PDFMaker 10.1 for Word |
| Document Author: | federicovi |
LE920
Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-21 (Preliminary)
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
APPLICABILITY TABLE
PRODUCT
LE920-- EU
LE920-- NA
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 2 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE
Notice
While reasonable efforts have been made to assure the accuracy of this document, Telit
assumes no liability resulting from any inaccuracies or omissions in this document, or from
use of the information obtained herein. The information in this document has been carefully
checked and is believed to be entirely reliable. However, no responsibility is assumed for
inaccuracies or omissions. Telit reserves the right to make changes to any products described
herein and reserves the right to revise this document and to make changes from time to time
in content hereof with no obligation to notify any person of revisions or changes. Telit does
not assume any liability arising out of the application or use of any product, software, or
circuit described herein; neither does it convey license under its patent rights or the rights of
others.
It is possible that this publication may contain references to, or information about Telit
products (machines and programs), programming, or services that are not announced in your
country. Such references or information must not be construed to mean that Telit intends to
announce such Telit products, programming, or services in your country.
Copyrights
This instruction manual and the Telit products described in this instruction manual may be,
include or describe copyrighted Telit material, such as computer programs stored in
semiconductor memories or other media. Laws in the Italy and other countries preserve for
Telit and its licensors certain exclusive rights for copyrighted material, including the
exclusive right to copy, reproduce in any form, distribute and make derivative works of the
copyrighted material. Accordingly, any copyrighted material of Telit and its licensors
contained herein or in the Telit products described in this instruction manual may not be
copied, reproduced, distributed, merged or modified in any manner without the express
written permission of Telit. Furthermore, the purchase of Telit products shall not be deemed
to grant either directly or by implication, estoppel, or otherwise, any license under the
copyrights, patents or patent applications of Telit, as arises by operation of law in the sale of a
product.
Computer Software Copyrights
The Telit and 3rd Party supplied Software (SW) products described in this instruction manual
may include copyrighted Telit and other 3rd Party supplied computer programs stored in
semiconductor memories or other media. Laws in the Italy and other countries preserve for
Telit and other 3rd Party supplied SW certain exclusive rights for copyrighted computer
programs, including the exclusive right to copy or reproduce in any form the copyrighted
computer program. Accordingly, any copyrighted Telit or other 3rd Party supplied SW
computer programs contained in the Telit products described in this instruction manual may
not be copied (reverse engineered) or reproduced in any manner without the express written
permission of Telit or the 3rd Party SW supplier. Furthermore, the purchase of Telit products
shall not be deemed to grant either directly or by implication, estoppel, or otherwise, any
license under the copyrights, patents or patent applications of Telit or other 3rd Party supplied
SW, except for the normal non-exclusive, royalty free license to use that arises by operation
of law in the sale of a product.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 3 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
Usage and Disclosure Restrictions
License Agreements
The software described in this document is the property of Telit and its licensors. It is
furnished by express license agreement only and may be used only in accordance with the
terms of such an agreement.
Copyrighted Materials
Software and documentation are copyrighted materials. Making unauthorized copies is
prohibited by law. No part of the software or documentation may be reproduced, transmitted,
transcribed, stored in a retrieval system, or translated into any language or computer language,
in any form or by any means, without prior written permission of Telit
High Risk Materials
Components, units, or third-party products used in the product described herein are NOT
fault-tolerant and are NOT designed, manufactured, or intended for use as on-line control
equipment in the following hazardous environments requiring fail-safe controls: the operation
of Nuclear Facilities, Aircraft Navigation or Aircraft Communication Systems, Air Traffic
Control, Life Support, or Weapons Systems (High Risk Activities"). Telit and its supplier(s)
specifically disclaim any expressed or implied warranty of fitness for such High Risk
Activities.
Trademarks
TELIT and the Stylized T Logo are registered in Trademark Office. All other product or
service names are the property of their respective owners.
Copyright Š Telit Communications S.p.A. 2012.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 4 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
Contents
1.
2.
Introduction ........................................................................................................... 9
1.1.
Scope ............................................................................................................................ 9
1.2.
Audience ....................................................................................................................... 9
1.3.
Contact Information, Support ...................................................................................... 9
1.4.
Document Organization ............................................................................................. 10
1.5.
Text Conventions ........................................................................................................ 11
1.6.
Related Documents ................................................................................................... 11
General Product Description ................................................................................ 12
2.1.
Overview ..................................................................................................................... 12
2.2.
LE920 Mechanical Dimensions .................................................................................. 13
2.3.
Weight ........................................................................................................................ 13
2.4.
Environmental requirements .................................................................................... 14
2.4.1.
Temperature range ........................................................................................................ 14
2.4.2.
RoHS compliance ........................................................................................................... 14
2.5.
3.
Operating Frequency ................................................................................................. 15
2.5.1.1.
WCDMA1700 â B4 .................................................................................................. 15
2.5.1.2.
(LE920-NA only) ...................................................................................................... 15
2.5.1.3.
1710 ~ 1755 .............................................................................................................. 15
2.5.1.4.
2110 ~ 2155 .............................................................................................................. 15
2.5.1.5.
Tx: 1312 ~ 1513 ........................................................................................................ 15
2.5.1.6.
Rx: 9662 ~ 9938 ....................................................................................................... 15
2.5.1.7.
400 MHz .................................................................................................................. 15
LE920 Module Connections .................................................................................. 17
3.1.
PIN-OUT ..................................................................................................................... 17
3.1.1.
4.
LGA Pads Layout ............................................................................................................ 24
Hardware Commands .......................................................................................... 25
4.1.
Turning ON the LE920 ................................................................................................ 25
4.2.
Initialization and Activation state............................................................................... 25
4.3.
Turning OFF the LE920 .............................................................................................. 27
4.3.1.
Shutdown by Software Command .................................................................................. 28
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 5 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-054.3.2.
Hardware Shutdown ...................................................................................................... 29
4.3.3.
Hardware Unconditional Restart ................................................................................... 30
4.3.4.
Hardware Unconditional Shutdown ............................................................................... 31
4.4.
5.
Summary of Turning ON and OFF the module .......................................................... 32
Power Supply ....................................................................................................... 33
5.1.
Power Supply Requirements ..................................................................................... 33
5.2.
General Design Rules ................................................................................................ 35
5.2.1.
6.
Electrical Design Guidelines .......................................................................................... 35
5.2.1.1.
+ 5V Input Source Power Supply Design Guidelines .............................................. 35
5.2.1.2.
+ 12V Input Source Power Supply Design Guidelines............................................. 36
5.2.1.3.
Battery Source Power Supply Design Guidelines................................................... 38
5.2.2.
Thermal Design Guidelines............................................................................................ 39
5.2.3.
Power Supply PCB Layout Guidelines ........................................................................... 40
Antenna(s) ........................................................................................................... 42
6.1.
GSM/WCDMA/LTE Antenna Requirements ............................................................... 42
6.2.
GSM/WCDMA/LTE Antenna â PCB line Guidelines ................................................... 43
6.3.
GSM/WCDMA/LTE Antenna â Installation Guidelines ............................................... 44
6.4.
Antenna Diversity Requirements............................................................................... 44
6.5.
GPS/GNSS Antenna Requirements ........................................................................... 45
6.5.1.
Combined GPS/GNSS Antenna ...................................................................................... 45
6.5.2.
Linear and Patch GPS/GNSS Antenna ........................................................................... 46
6.5.3.
Front End Design Considerations .................................................................................. 46
6.5.4.
GPS/GNSS Antenna - PCB Line Guidelines ................................................................... 46
6.5.5.
GPS/GNSS Antenna â Installation Guidelines ............................................................... 47
7.
Logic Level Specifications .................................................................................... 48
8.
USB Port .............................................................................................................. 49
9.
Serial Ports .......................................................................................................... 50
9.1.
Modem Serial Port 1 .................................................................................................. 51
9.2.
Modem Serial Port 2 .................................................................................................. 52
9.3.
RS232 Level Translation ............................................................................................ 52
10.
Audio Section Overview ..................................................................................... 54
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 6 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
10.1.
11.
Digital Audio ........................................................................................................... 54
General Purpose I/O.......................................................................................... 56
11.1.
Logic Level Specifications ...................................................................................... 57
11.2.
Using a GPIO Pad as Input ...................................................................................... 57
11.3.
Using a GPIO Pad as Output ................................................................................... 58
11.4.
Using the Temperature Monitor Function ............................................................. 59
11.4.1.
Short Description ........................................................................................................... 59
11.5.
Indication of Network Service Availability.............................................................. 59
11.6.
RTC Bypass Out ...................................................................................................... 60
11.7.
VAUX Power Output ................................................................................................ 60
12.
ADC section ...................................................................................................... 61
12.1.
13.
ADC Converter ........................................................................................................ 61
12.1.1.
Description ..................................................................................................................... 61
12.1.2.
Using ADC Converter ..................................................................................................... 61
Mounting the module on your board .................................................................. 62
13.1.
General ................................................................................................................... 62
13.2.
Finishing & Dimensions ......................................................................................... 62
13.3.
Recommended foot print for the application ......................................................... 63
13.4.
Stencil ..................................................................................................................... 64
13.5.
PCB Pad Design ...................................................................................................... 64
13.6.
Recommendations for PCB Pad Dimensions (mm)............................................... 64
13.7.
Solder Paste ........................................................................................................... 66
13.7.1.
14.
Solder Reflow ................................................................................................................. 66
Application guide .............................................................................................. 68
14.1.
Debug of the LE920 in production .......................................................................... 68
14.2.
Bypass capacitor on Power supplies ..................................................................... 69
14.3.
SIM interface........................................................................................................... 69
14.4.
EMC recommendations (TBD) ................................................................................ 70
14.5.
Download and Debug Port ...................................................................................... 71
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 7 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
15.
Packing system ................................................................................................. 72
15.1.
Tray Drawing........................................................................................................... 73
15.2.
Moisture Sensibility ................................................................................................ 74
16.
Safety Recommendations .................................................................................. 75
17.
Document History ............................................................................................. 76
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 8 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
1.
1.1.
Introduction
Scope
The aim of this document is the description of some hardware solutions useful for developing
a product with the Telit LE920-EU/NA module. All the features and solutions detailed are
applicable to all LE920, whereas âLE920â is intended the modules listed in the applicability
table.
When a specific feature is applicable to a specific product, it will be clearly highlighted.
1.2.
Audience
This document is intended for Telit customers, who are integrators, about to implement their
applications using our LE920 module.
1.3.
Contact Information, Support
For general contact, technical support, to report documentation errors and to order manuals,
contact Telitâs Technical Support Center (TTSC) at:
TS-EMEA@telit.com
TS-NORTHAMERICA@telit.com
TS-LATINAMERICA@telit.com
TS-APAC@telit.com
Alternatively, use:
http://www.telit.com/en/products/technical-support-center/contact.php
For detailed information about where you can buy the Telit modules or for recommendations
on accessories and components visit:
http://www.telit.com
To register for product news and announcements or for product questions contact Telitâs
Technical Support Center (TTSC).
Our aim is to make this guide as helpful as possible. Keep us informed of your comments and
suggestions for improvements.
Telit appreciates feedback from the users of our information.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 9 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
1.4.
Document Organization
This document contains the following chapters:
Chapter 1: âIntroductionâ provides a scope for this document, target audience, contact and
support information, and text conventions.
Chapter 2: âGeneral Product Descriptionâ gives an overview of the features of the product.
Chapter 3: âLE920 Module Connectionsâ deals with the pin out configuration and layout.
Chapter 4: âHardware Commandsâ How to control the module via hardware
Chapter 5: âPower Supplyâ deals on supply and consumption.
Chapter 6: âAntennaâ The antenna connection and board layout design are the most important
parts in the full product design
Chapter 7: âLogic Level specificationsâ Specific values adopted in the implementation of
logic levels for this module.
Chapter 8: âUSB Portâ
Chapter 9: âSerial Portsâ
Chapter 10: âAudio Section Overviewâ
Chapter 11: âGeneral Purpose I/Oâ How the general purpose I/O pads can be configured.
Chapter 12 âDAC and ADC Sectionâ Deals with these two kind of converters.
Chapter 13: âMounting the module on your boardâ
Chapter 14: âApplication Guidesâ
Chapter 15: âPacking Systemâ
Chapter 16: âConformity Assessmentsâ
Chapter 17: âSafety Recommendationsâ
Chapter 18: âDocument Historyâ
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 10 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
1.5.
Text Conventions
Danger â This information MUST be followed or catastrophic equipment failure or bodily
injury may occur.
Caution or Warning â Alerts the user to important points about integrating the module, if
these points are not followed, the module and end user equipment may fail or malfunction.
Tip or Information â Provides advice and suggestions that may be useful when
integrating the module.
All dates are in ISO 8601 format, i.e. YYYY-MM-DD.
1.6.
Related Documents
LE920-EU/NA Product Description, 80407ST10118A
LE920-EU/NA AT command reference guide, 80407ST10116A
Telit EVK2 User Guide, 1vv0300704
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 11 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
2.
2.1.
General Product Description
Overview
The aim of this document is the description of some hardware solutions useful for developing
a product with the Telit LE920 module.
In this document all the basic functions of a mobile phone will be taken into account; for each
one of them a proper hardware solution will be suggested and eventually the wrong solutions
and common errors to be avoided will be evidenced. Obviously this document cannot
embrace the whole hardware solutions and products that may be designed. The wrong
solutions to be avoided must be considered as mandatory, while the suggested hardware
configurations must not be considered mandatory, instead the information given must be used
as a guide and a starting point for properly developing your product with the Telit LE920
module.
NOTICE:
The integration of the GSM/GPRS/EGPRS/WCDMA/HSPA+/LTE LE920 cellular module
within user application must be done according to the design rules described in this manual.
The information presented in this document is believed to be accurate and reliable. However,
no responsibility is assumed by Telit Communication S.p.A. for its use, such as any
infringement of patents or other rights of third parties which may result from its use. No
license is granted by implication or otherwise under any patent rights of Telit Communication
S.p.A. other than for circuitry embodied in Telit products. This document is subject to change
without notice.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 12 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
2.2.
LE920 Mechanical Dimensions
The Telit LE920 module overall dimensions are:
2.3.
Length:
34 mm
Width:
40 mm
Thickness:
2.9 mm
Weight
The module weight of LE920-EU/NA is about 9.0 gram.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 13 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
2.4.
Environmental requirements
2.4.1.
Temperature range
Note
Operating Temperature
Range
Storage and non-operating
Temperature Range
â20°C ~ +55°C
The module is fully functional (*) in all the
temperature range, and it fully meets the ETSI
specifications.
â40°C ~ +85°C
The module is fully functional (*) in all the
temperature range. Temperatures outside of
the range â20°C á +55°C might slightly
deviate from ETSI specifications.
â40°C ~ +85°C
(*)Functional: the module is able to make and receive voice calls, data calls and SMS.
2.4.2.
RoHS compliance
As a part of Telit corporate policy of environmental protection, the LE920 complies with the
RoHS (Restriction of Hazardous Substances) directive of the European Union (EU directive
2002/95/EG).
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 14 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
2.5.
Operating Frequency
The operating frequencies in GSM850, EGSM900, DCS1800, PCS1900, WCDMA & LTE
modes are conformed to the 3GPP specifications.
Mode
Freq. TX (MHz)
Freq. RX (MHz)
Channels
TX - RX
offset
GSM850
824 ~ 849
869 ~ 894
128 ~ 251
45 MHz
890 ~ 915
935 ~ 960
0 ~ 124
45 MHz
880 ~ 890
925 ~ 935
975 ~ 1023
45 MHz
DCS1800
1710 ~ 1785
1805 ~ 1880
512 ~ 885
95MHz
PCS1900
1850 ~ 1910
1930 ~ 1990
512 ~ 810
80MHz
EGSM900
WCDMA2100 â B1
(LE920 both models)
WCDMA1900 â B2
(LE920-NA only)
WCDMA1800 â B3
Tx: 9612 ~ 9888
1920 ~ 1980
2110 ~ 2170
1850 ~ 1910
1930 ~ 1990
1710 ~ 1785
1805 ~ 1880
(LE920-NA only)
WCDMA850 â B5
(LE920-NA only)
WCDMA800 â B6
(LE920-NA only)
WCDMA900 â B8
(LE920-EU only)
LTE2100 â B1
(LE920 both models)
190MHz
Tx: 9262 ~ 9538
Rx: 9662 ~ 9938
Tx: 937 ~ 1288
80MHz
95MHz
Rx: 1162 ~ 1513
(LE920-EU only)
WCDMA1700 â B4
Rx: 10562 ~ 10838
1710 ~ 1755
2110 ~ 2155
824 ~ 849
869 ~ 894
830 ~ 840
875 ~ 885
880 ~ 915
925 ~ 960
1920 ~ 1980
2110 ~ 2170
Tx: 1312 ~ 1513
Rx: 9662 ~ 9938
400 MHz
Tx: 4132 ~ 4233
Rx: 4357 ~ 4458
45MHz
Tx: 4162 ~ 4188
Rx: 4387 ~ 4413
Tx: 2712 ~ 2863
Rx: 2937 ~ 3088
Tx: 18000 ~ 18599
Rx: 0 ~ 599
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
45MHz
45MHz
190MHz
Page 15 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05LTE1900 â B2
(LE920-NA only)
LTE1800 â B3
1850 ~ 1910
1930 ~ 1990
1710 ~ 1785
1805 ~ 1880
(LE920-EU only)
LTE1700 â B4
(LE920-NA only)
LTE850 â B5
(LE920-NA only)
LTE2600 â B7
(LE920-EU only)
LTE900 â B8
(LE920-EU only)
LTE700 â B17
(LE920-NA only)
LTE800 â B20
(LE920-EU only)
Tx: 18600 ~ 19199
Rx: 600 ~ 1199
Tx: 19200 ~ 19949
80MHz
95MHz
Rx: 1200 ~ 1949
1710~ 1755
2110 ~ 2155
824 ~ 849
869 ~ 894
2500 ~ 2570
2620 ~ 2690
880 ~ 915
925 ~ 960
704 ~ 716
734 ~ 746
832 ~ 862
791 ~ 821
Tx: 19950 ~ 20399
Rx: 1950 ~ 2399
Tx: 20400 ~ 20649
Rx: 2400 ~ 2649
Tx: 20750 ~ 21449
Rx: 2750 ~ 3449
Tx: 21450 ~ 21799
Rx: 3450 ~ 3799
Tx: 23730 ~ 23849
Rx: 5730 ~ 5849
Tx: 24150 ~ 24449
Rx: 6150 ~ 6449
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
400MHz
45MHz
120MHz
45MHz
30MHz
-41MHz
Page 16 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
3.
3.1.
LE920 Module Connections
PIN-OUT
PAD
Signal
I/O
Function
USB HS 2.0 Communication Port
I/O USB differential Data(+)
D19 USB_D+
USB_DI/O USB differential Data(+)
F19
AI Power sense for the internal USB transceiver
A18 USB_VBUS
Asynchronous UART â Prog. / data +HW Flow Control
Serial data input (TXD) from DTE
AH19 C103/TXD
O Serial data output to DTE
AF19 C104/RXD
Input for Data terminal ready signal (DTR) from DTE
AC18 C108/DTR
Input for Request to send signal (RTS) from DTE
AA18 C105/RTS
O Output for Clear to send signal (CTS) to DTE
AK19 C106/CTS
O Output for Data carrier detect signal (DCD) to DTE
AE18 C109/DCD
O Output for Data set ready signal (DSR) to DTE
AG18 C107/DSR
O Output for Ring indicator signal (RI) to DTE
AJ18 C125/RING
Asynchronous Auxiliary UART
O Auxillary UART (TX Data to DTE)
AB19 TXD_AUX
Auxillary UART (RX Data from DTE)
AD19 RXD_AUX
SIM Card Interface 1
O External SIM signal â Clock
A10 SIMCLK1
O External SIM signal â Reset
B11 SIMRST1
SIMIO1
I/O External SIM signal - Data I/O
B9
SIMIN1
External SIM signal - Presence (active low)
B7
SIMVCC1
External SIM signal â Power supply for the SIM
A8
Audio
EAR1_MT+
AO Earphone signal output1, phase +
B5
EAR1_MTAO Earphone signal output1, phase A4
MIC1_MT+
AI Mic signal input1, phase +
B3
MIC1_MTAI Mic signal input1, phase A2
EAR2_MT+
AO Earphone signal output2, phase +
E2
EAR2_MTAO Earphone signal output2, phase D1
MIC2_MT+
AI Mic signal input2, phase +
C2
MIC2_MTAI Mic signal input2, phase B1
Digital Voice interface (DVI)
O Digital Voice interface (WA0 master output)
D11 DVI_WA0
DVI_RX
Digital Voice interface (RX)
C8
DVI_TX
O Digital Voice interface (TX)
D9
Type
COMMENT
Power
1.8V
1.8V
1.8V
1.8V
1.8V
1.8V
1.8V
1.8V
1.8V
1.8V
1.8/2.85V
1.8/2.85V
1.8/2.85V
1.8V
1.8/2.85V
Audio
Audio
Audio
Audio
Audio
Audio
Audio
Audio
1.8V
1.8V
1.8V
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 17 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05PAD
Signal
C10 DVI_CLK
Digital I/O
GPIO_01
F9
E10 GPIO_02
GPIO_03
F11
E12 GPIO_04
GPIO_05
F13
E14 GPIO_06
R18 GPIO_07
GPIO_08
S19
U19 GPIO_09
W19 GPIO_10
RF Section
AD1 Antenna
AU9 ANT_DIV
GPS Section
ANT_GPS
S1
Miscellaneous Function
AP1 RESET#
AS1 ON_OFF#
AN12 SHDN_N
I/O
Function
O Digital Voice interface (CLK master output)
Type
1.8V
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
1.8V
1.8V
1.8V
1.8V
1.8V
1.8V
1.8V
1.8V
1.8V
1.8V
I/O GSM/EDGE/UMTS/LTE Antenna (50 Ohm)
UMTS/LTE Antenna Diversity Input (50 Ohm)
RF
RF
GPS Antenna (50 Ohm)
RF
Reset Input
Input Command for Power ON
Unconditional Shut down Input
F17
VRTC
P17
VAUX/PWRMON O
ADC_IN1
D5
ADC_IN2
E6
ADC_IN3
F7
AU3 STAT_LED
AN10 SW_RDY
Power Supply
AP17 VBATT
AP19 VBATT
AR18 VBATT
AS17 VBATT_PA
AS19 VBATT_PA
AT18 VBATT_PA
AU17 VBATT_PA
AU19 VBATT_PA
GND
A6
GPIO_01
GPIO_02
GPIO_03
GPIO_04
GPIO_05
GPIO_06
GPIO_07
GPIO_08
GPIO_09
GPIO_10
AI VRTC Backup Capacitor
Power
COMMENT
Active Low
Active Low
Active Low
To be used to
back up the
RTC section
Supply Output for External Accessories / Power ON
1.8V
Monitor
AI Analog/Digital Converter Input 1
Analog
AI Analog/Digital Converter Input 2
Analog
AI Analog/Digital Converter Input 3
Analog
O Status Indicator LED
1.8V
O Indicates that the boot sequence completed successfully 1.8V
Main Power Supply (Digital Section)
Main Power Supply (Digital Section)
Main Power Supply (Digital Section)
Main Power Supply (RF Transmit Power Section)
Main Power Supply (RF Transmit Power Section)
Main Power Supply (RF Transmit Power Section)
Main Power Supply (RF Transmit Power Section)
Main Power Supply (RF Transmit Power Section)
Ground
Power
Power
Power
Power
Power
Power
Power
Power
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 18 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05PAD
A12
B13
B15
B17
C4
C6
D3
D7
E18
F1
G18
H19
M1
N2
P1
P3
R2
T2
T18
U1
V18
W1
X2
X18
Y1
Y19
AA2
AB1
AC2
AE2
AF1
AG2
AH1
AJ2
AK1
AK17
AL18
AM17
AM19
AN16
AN18
Signal
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
GND
I/O
Function
Type
COMMENT
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 19 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05PAD
Signal
AP3 GND
AP5 GND
AP7 GND
AP9 GND
AP11 GND
AP13 GND
AP15 GND
AR2 GND
AR4 GND
AR6 GND
AR8 GND
AR10 GND
AR12 GND
AR14 GND
AR16 GND
AS5 GND
AS7 GND
AS9 GND
AS11 GND
AS13 GND
AS15 GND
AT4 GND
AT6 GND
AT8 GND
AT10 GND
AT12 GND
AT14 GND
AT16 GND
AU1 GND
AU5 GND
AU7 GND
AU11 GND
AU15 GND
Reserved
C12 Reserved
A14 Reserved
A16 Reserved
M17 Reserved
AN6 Reserved
Reserved
V2
C14 Reserved
I/O
Function
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Type
COMMENT
Page 20 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05PAD
D13
C16
D17
E16
C18
D15
F15
E4
E8
F3
F5
G2
H1
H3
H17
J2
J18
K1
K3
K17
K19
L2
L18
M3
M19
N18
P19
S3
S17
U3
U17
W3
W17
Y3
Y17
AB3
AB17
AD3
AD17
AF3
AF17
Signal
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reseved
I/O
Function
Type
COMMENT
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 21 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05PAD
AH3
AH17
AK3
AL2
AM1
AM3
AN2
AN4
AN8
AN14
AS3
AT2
B19
AU13
Signal
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
I/O
Function
Type
COMMENT
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
Reserved
NOTE:
When the UART signals are used as the communication port between the Host to the Modem:
DTR pin must be connected in order to enter LE920âs power saving mode.
RI pin must be connected in order to wake up the host when a call is coming in sleep
mode of host.
RTS must be connected to the GND (on the module side) if flow control is not used
In case UART port isnât used, all UART signals may be left disconnected
NOTE:
RESERVED pins must not be connected
NOTE:
If not used, almost all pins must be left disconnected. The only exceptions are the following:
PAD
AP17,AP19,AR18,AS17,AS19,AT18,AU17,AU19
A6,A12,B13,B15,B17,C4,C6,D3,D7,E18,F1,G18,H19,
M1,N2,P1,P3,R2,T2,T18,U1,V18,W1,X2,X18,Y1,Y19,
AA2,AB1,AC2,AE2,AF1,AG2,AH1,AJ2,AK1,AK17,
AL18,AM17,AM19,AN16,AN18,AP3,AP5,AP7,AP9,
AP11,AP13,AP15,AR2,AR4AR6,AR8,AR10,AR12,
AR14,AR16,AS5,AS7,AS9,AS11,AS13,AS15,AT4,
AT6,AT8,AT10,AT12,AT14,AT16,AU1,AU5,AU7,
Signal
VBATT & VBATT_PA
GND
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 22 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05AU11,AU15
AS1
ON/OFF*
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 23 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
3.1.1.
LGA Pads Layout
NOTE:
The pin defined as RES has to be considered RESERVED and not connected on any
pin in the application. The related area on the application has to be kept empty.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 24 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
4.
4.1.
Hardware Commands
Turning ON the LE920
To turn on LE920, the pad ON# must be tied low for at least 1 second and then released.
The maximum current that can be drained from the ON# pad is 0.1 mA.
A simple circuit to power on the module is illustrated below:
4.2.
Initialization and Activation state
Upon turning on LE920 module, The LE920 is not activated yet because the boot sequence of
LE920 is still going on internally. It takes about 10 seconds to complete the initializing the
module internally.
For this reason, it would be useless to try to access LE920 during the Initialization state as
below. To get the desirable stability, The LE920 needs at least 15 seconds after the
PWRMON goes High to become operational by reaching the activation state.
During the Initialization state, any kind of AT-command is not available. DTE must be
waiting for the Activation state to communicate with LE920.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 25 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05NOTE:
To check if the LE920 has powered on, the hardware line PWRMON must be monitored.
When PWRMON goes high, the module has powered on.
NOTE:
Do not use any pull up resistor on the ON# line, it is internally pulled up. Using pull up
resistor may bring to latch up problems on the LE920 power regulator and improper power
on/off of the module. The line ON# must be connected only in open collector configuration.
NOTE:
In this document all the lines are inverted. Active low signals are labeled with a name that
ends with "#" or with a bar over the name.
NOTE:
In order to avoid a back powering effect it is recommended to avoid having any HIGH logic
level signal applied to the digital pins of the module when is powered OFF or during an
ON/OFF transition.
For example:
1- Let us assume you need to drive the ON# pad with a totem pole output of a +1.8/5 V
microcontroller (uP_OUT1):
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 26 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
4.3.
Turning OFF the LE920
Turning off the device can be done in three ways:
by Software command
by Hardware shutdown
by Hardware Unconditional Restart
by Hardware Unconditional shutdown
When the device is shut down by software command or by hardware shutdown, it issues to
the network a detach request that informs the network that the device will not be reachable
any more.
TIP:
To check if the device has powered off, hardware line PWRMON must be monitored. When
PWRMON goes low it can be considered the device has powered off.
NOTE:
In order to avoid a back powering effect it is recommended to avoid having any HIGH logic
level signal applied to the digital pins of the module when is powered OFF or during an
ON/OFF transition.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 27 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
4.3.1.
Shutdown by Software Command
LE920 can be shut down by a software command.
When a shut down command is sent, LE920 goes into the finalization state and finally will
shut down PWRMON at the end of this state.
The period of the finalization state can differ according to the situation in which the LE920 is
so it cannot be fixed definitely.
Normally it will be above 10 seconds later from sending a shut down command and DTE
should monitor the status of PWRMON to see the actual power off.
TIP:
To check if the device has powered off, hardware line PWRMON must be monitored. When
PWRMON goes low, the device has powered off.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 28 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
4.3.2.
Hardware Shutdown
To turn OFF LE920 the pad ON/OFF# must be tied low for at least 2 seconds and then
released. Same circuitry and timing for the power on must be used.
When the hold time of ON/OFF# is above 2 seconds, LE920 goes into the finalization state
and finally will shut down PWRMON at the end of this state.
The period of the finalization state can differ according to the situation in which the LE920 is
so it cannot be fixed definitely.
Normally it will be above 10 seconds later from releasing ON/OFF# and DTE should monitor
the status of PWRMON to see the actual power off.
TIP:
To check if the device has powered off, hardware line PWRMON must be monitored. When
PWRMON goes low, the device has powered off.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 29 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
4.3.3.
Hardware Unconditional Restart
To unconditionally restart LE920, the pad RESET# must be tied low for at least 200
milliseconds and then released.
A simple circuit to do it is:
RESET#
Unconditional Restart
impulse
GND
NOTE:
Do not use any pull up resistor on the RESET# line or any totem pole digital output. Using
pull up resistor may bring to latch up problems on the LE920 power regulator and improper
functioning of the module. The line RESET# must be connected only in open collector
configuration.
TIP:
The unconditional hardware Restart must always be implemented on the boards and the
software must use it as an emergency exit procedure, and not as a normal power-off operation
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 30 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05For example:
1- Let us assume you need to drive the RESET# pad with a totem pole output of a +1.8/5 V
microcontroller (uP_OUT2):
SHDN_N
Unconditional Shutdown
impulse
GND
4.3.4.
Hardware Unconditional Shutdown
To unconditionally Shutdown LE920, the pad SHDN_N must be tied low for at least 200
milliseconds and then released.
A simple circuit to do it is:
SHDN_N
Unconditional Shutdown
impulse
GND
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 31 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05NOTE:
Do not use any pull up resistor on the SHDN_N line or any totem pole digital output. Using
pull up resistor may bring to latch up problems on the LE920 power regulator and improper
functioning of the module. The line SHDN_N must be connected only in open collector
configuration.
Note:
The unconditional hardware SHDN_N must always be implemented on the boards and the
software must use it as an emergency exit procedure, and not as a normal power-off operation
4.4.
Summary of Turning ON and OFF the module
Below chart describes the overall sequences for Turning ON and OFF.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 32 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
5.
Power Supply
The power supply circuitry and board layout are a very important part in the full product
design and they strongly reflect on the product overall performances. Read carefully the
requirements and the guidelines that will follow for a proper design.
5.1.
Power Supply Requirements
The LE920 power requirements are:
Power Supply
Nominal Supply Voltage
Max Supply Voltage
Supply Voltage Range
Mode
SWITCHED OFF
Switched Off
IDLE mode
WCDMA
AT+CFUN=1
GSM
LTE
LE920 current consumption
Average(mA)
Mode Description
AT+CFUN=4
AT+CFUN=5
3.8V
4.2V
3.3Vâ 4.2V
40 uA
Standby mode; no call in progress
16
16
16
Normal mode; full functionality of the module
10
Disabled TX and RX; modules is not registered on the
network
WCDMA
1.7
GSM
1.9
LTE (0dBm)
LTE (22dBm)
WCDMA Voice
WCDMA HSDPA (0dBm)
WCDMA HSDPA (22dBm)
Module supplied but switched Off
DRx9
Operative mode (LTE)
203
LTE data call channel BW 5MHz,RB=1, TX = 0dBm)
540
LTE data call (channel BW 5MHz,RB=1, TX = 22dBm)
Operative mode (WCDMA)
185
WCDMA voice call (TX = 10dBm)
100
WCDMA data call (RMC, TX = 0dBm)
390
WCDMA data call (RMC, TX = 22dBm)
Operative mode (GSM)
GSM TX and RX mode
GSM900 PL5
DCS1800 PL0
GPRS 4TX + 1RX
290
170
GSM900 PL5
410
DCS1800 PL0
EDGE 4TX + 1RX
320
GSM Voice Call
GPRS Sending data mode
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 33 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05GSM900 PL5
DCS1800 PL0
255
240
EDGE Sending data mode
* Worst/best case depends on network configuration and is not under module control.
TIP:
The electrical design for the Power supply must be made ensuring that it will be capable of a
peak current output of at least 2A.
In GSM/GPRS mode, RF transmission is not continuous and it is packed into bursts at a base
frequency of about 216 Hz, and the relative current peaks can be as high as about 2A.
Therefore the power supply has to be designed in order to withstand these current peaks
without big voltage drops; this means that both the electrical design and the board layout must
be designed for this current flow. If the layout of the PCB is not well designed, a strong noise
floor is generated on the ground; this will reflect on all the audio paths producing an audible
annoying noise at 216 Hz; if the voltage drops during the peak, current absorption is too
much. The device may even shut down as a consequence of the supply voltage drop.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 34 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
5.2.
General Design Rules
The principal guidelines for the Power Supply Design embrace three different design steps:
5.2.1.
the electrical design
the thermal design
the PCB layout
Electrical Design Guidelines
The electrical design of the power supply depends strongly on the power source where this
power is drained. We will distinguish them into three categories:
5.2.1.1.
+5V input (typically PC internal regulator output)
+12V input (typically automotive)
battery
+ 5V Input Source Power Supply Design Guidelines
The desired output for the power supply is 3.8V, hence there is not a big
difference between the input source and the desired output and a linear regulator
can be used. A switching power supply will not be suited because of the low
drop-out requirements.
When using a linear regulator, a proper heat sink must be provided in order to
dissipate the power generated.
A Bypass low ESR capacitor of adequate capacity must be provided in order to
cut the current absorption peaks close to LE920
usually suited.
Make sure the low ESR capacitor on the power supply output (usually a tantalum
one) is rated at least 10V.
A protection diode must be inserted close to the power input, in order to save
LE920 from power polarity inversion.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 35 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05An example of linear regulator with 5V input is:
5.2.1.2.
+ 12V Input Source Power Supply Design Guidelines
The desired output for the power supply is 3.8V, hence due to the big difference
between the input source and the desired output, a linear regulator is not suited
and must not be used. A switching power supply will be preferable because of its
better efficiency especially with the 2A peak current load represented by LE920.
When using a switching regulator, a 500kHz or more switching frequency
regulator is preferable because of its smaller inductor size and its faster transient
response. This allows the regulator to respond quickly to the current peaks
absorption.
In any case, the frequency and Switching design selection is related to the
application to be developed due to the fact the switching frequency could also
generate EMC interferences.
For car PB battery the input voltage can rise up to 15.8V and this must be kept in
mind when choosing components: all components in the power supply must
withstand this voltage.
A Bypass low ESR capacitor of adequate capacity must be provided in order to
s usually suited for
this.
Make sure the low ESR capacitor on the power supply output (usually a tantalum
one) is rated at least 10V.
For Car applications a spike protection diode must be inserted close to the power
input, in order to clean the supply from spikes.
A protection diode must be inserted close to the power input, in order to save
LE920 from power polarity inversion. This can be the same diode as for spike
protection.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 36 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05An example of switching regulator with 12V input is in the below schematic (it is split in 2
parts):
Switching regulator
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 37 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-055.2.1.3.
Battery Source Power Supply Design Guidelines
The desired nominal output for the power supply is 3.8V and the maximum
allowed voltage is 4.2V, hence a single 3.7V Li-Ion cell battery type is suited for
supplying the power to the Telit LE920 module. The three cells Ni/Cd or Ni/MH
3.6 V Nom. battery types or 4V PB types must not be used directly since their
maximum voltage can rise over the absolute maximum voltage for LE920 and
damage it.
NOTE:
Do not use any Ni-Cd, Ni-MH, and Pb battery types directly connected with LE920. Their use
can lead to overvoltage on LE920 and damage it. Use only Li-Ion battery types.
A Bypass low ESR capacitor of adequate capacity must be provided in order to
cut the current
Make sure the low ESR capacitor (usually a tantalum one) is rated at least 10V.
A protection diode must be inserted close to the power input, in order to save
LE920 from power polarity inversion. Otherwise the battery connector must be
done in a way to avoid polarity inversions when connecting the battery.
The battery capacity must be at least 500mAh in order to withstand the current
peaks of 2A; the suggested capacity is from 500mAh to 1000mAh.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 38 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
5.2.2.
Thermal Design Guidelines
The thermal design for the power supply heat sink must be done with the following
specifications:
Average current consumption during HSPA transmission @PWR level max in
LE920: 640mA (TBD)
Average current consumption during class12 GPRS transmission @PWR level
max: 680mA (TBD)
Average GPS current during GPS ON (Power Saving disabled) : 65mA (TBD)
NOTE:
The average consumption during transmissions depends on the power level at which the
device is requested to transmit via the network. The average current consumption hence varies
significantly.
NOTE:
The thermal design for the Power supply must be made keeping an average consumption at
the max transmitting level during calls of 640mA(HSPA)/680mA(GPRS) rms plus 65mA rms
for GPS in tracking mode.
Considering the very low current during idle, especially if Power Saving function is enabled,
it is possible to consider from the thermal point of view that the device absorbs current
significantly only during calls.
If we assume that the device stays in transmission for short periods of time (let us say few
minutes) and then remains for quite a long time in idle (let us say one hour), then the power
supply has always the time to cool down between the calls and the heat sink could be smaller
than the calculated for 640mA (HSPA)/680mA (GPRS) maximum RMS current. There could
even be a simple chip package (no heat sink).
Moreover in average network conditions the device is requested to transmit at a lower power
level than the maximum and hence the current consumption will be less than 640mA (HSPA)
/680mA (GPRS) (being usually around 250mA).
For these reasons the thermal design is rarely a concern and the simple ground plane where
the power supply chip is placed can be enough to ensure a good thermal condition and avoid
overheating.
For the heat generated by the LE920, you can consider it to be during transmission 2W max
during class12 GPRS upload. This generated heat will be mostly conducted to the ground
plane under the LE920; you must ensure that your application can dissipate heat.
In the WCDMA/HSPA mode, since LE920 emits RF signals continuously during
transmission, you must pay special attention how to dissipate the heat generated.
The current consumption will be up to about 640mA in HSPA (630mA in WCDMA)
continuously at the maximum TX output power (23dBm). Thus, you must arrange the PCB
area as large as possible under LE920 which you will mount. You must mount LE920 on the
large ground area of your application board and make many ground vias to dissipate the heat.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 39 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05The peak current consumption in the GSM mode is higher than that in WCDMA. However,
considering the heat sink is more important in case of WCDMA.
As mentioned before, a GSM signal is bursty, thus, the temperature drift is more insensible
than WCDMA. Consequently, if you prescribe the heat dissipation in the WCDMA mode,
you donât need to think more about the GSM mode.
5.2.3.
Power Supply PCB Layout Guidelines
As seen in the electrical design guidelines, the power supply must have a low ESR capacitor
on the output to cut the current peaks and a protection diode on the input to protect the supply
from spikes and polarity inversion. The placement of these components is crucial for the
correct working of the circuitry. A misplaced component can be useless or can even decrease
the power supply performances.
The Bypass low ESR capacitor must be placed close to the Telit LE920 power
input pads, or in the case the power supply is a switching type, it can be placed
close to the inductor to cut the ripple if the PCB trace from the capacitor to
LE920 is wide enough to ensure a drop-less connection even during the 2A
current peaks.
The protection diode must be placed close to the input connector where the power
source is drained.
The PCB traces from the input connector to the power regulator. IC must be wide
enough to ensure no voltage drops to occur when the 2A current peaks are
absorbed. Note that this is not made in order to save power loss but especially to
avoid the voltage drops on the power line at the current peaks frequency of 216
Hz that will reflect on all the components connected to that supply (also
introducing the noise floor at the burst base frequency.) For this reason while a
voltage drop of 300-400 mV may be acceptable from the power loss point of
view, the same voltage drop may not be acceptable from the noise point of view.
If your application does not have audio interface but only uses the data feature of
the Telit LE920, then this noise is not so disturbing and power supply layout
design can be more forgiving.
The PCB traces to LE920 and the Bypass capacitor must be wide enough to
ensure no significant voltage drops to occur when the 2A current peaks are
absorbed. This is a must for the same above-mentioned reasons. Try to keep this
trace as short as possible.
The PCB traces connecting the Switching output to the inductor and the
switching diode must be kept as short as possible by placing the inductor and the
diode very close to the power switching IC (only for switching power supply).
This is done in order to reduce the radiated field (noise) at the switching
frequency (usually 100-500 kHz).
The use of a good common ground plane is suggested.
The placement of the power supply on the board must be done in a way to
guarantee that the high current return paths in the ground plane are not
overlapped to any noise sensitive circuitry as the microphone amplifier/buffer or
earphone amplifier.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 40 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05x
The power supply input cables must be kept separately from noise sensitive lines
such as microphone/earphone cables.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 41 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
6.
Antenna(s)
The antenna connection and board layout design are the most important parts in the full
product design and they strongly reflect on the productâs overall performances. Read carefully
and follow the requirements and the guidelines for a proper design.
6.1.
GSM/WCDMA/LTE Antenna Requirements
The antenna for a Telit LE920 device must fulfill the following requirements:
GSM / WCDMA/ LTE Antenna Requirements
Frequency
range
Bandwidth
Gain
Impedance
Input power
Depending by frequency band(s) provided by the network operator, the
customer must use the most suitable antenna for that/those band(s)
LE920-EU
LE920-NA
GSM850 : 70 MHz
GSM850 : 70 MHz
GSM900 : 80 MHz
GSM900 : 80 MHz
GSM1800(DCS) : 170 MHz
GSM1800(DCS) : 170 MHz
GSM1900(PCS) : 140 MHz
GSM1900(PCS) : 140 MHz
WCDMA band I(2100) : 250 MHz
WCDMA band I(2100) : 250 MHz
WCDMA band II(1900) : 140 MHz
WCDMA band III(1800) : 170 MHz WCDMA band IV(1700) : 445 MHz
WCDMA band VIII(900) : 80 MHz
WCDMA band V(850) : 70 MHz
LTE Band I(2100) : 250 MHz
WDCMA band VI(800): 70MHz
LTE band III(1800) : 170 MHz
LTE Band I(2100) : 250 MHz
LTE Band VII(2600) : 190 MHz
LTE Band II(1900) : 140 MHz
LTE Band VIII(900) : 80 MHz
LTE Band IV(1700) : 445 MHz
LTE Band XX(800) : 71 MHz
LTE Band V (850) : 70 MHz
LTE Band XVII(700) : 42 MHz
Gain < 3dBi
50 Ohm
> 33dBm(2 W) peak power in GSM
> 24dBm Average power in WCDMA & LTE
<= 10:1
VSWR
absolute max
<= 2:1
VSWR
recommended
When using the Telit LE920, since thereâs no antenna connector on the module, the antenna
must be connected to the LE920 antenna pad (AD1) by means of a transmission line
implemented in the PCB.
In the case that the antenna is not directly connected at the antenna pad of the LE920, then a
PCB line is required in order to connect with it or with its connector.
This transmission line shall fulfill the following requirements:
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 42 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05Antenna Line on PCB Requirements
Characteristic Impedance
50Ohm
Max Attenuation
0.3dB
Coupling with other signals shall be avoided
Cold End (Ground Plane) of antenna shall be equipotential to the LE920 ground pads
Furthermore if the device is developed for the US and/or Canada market, it must comply to
the FCC and/or IC approval requirements:
This device is to be used only for mobile and fixed application. The antenna(s) used for this
transmitter must be installed to provide a separation distance of at least 20 cm from all
persons and must not be co-located or operating in conjunction with any other antenna or
transmitter. End-Users must be provided with transmitter operation conditions for satisfying
RF exposure compliance. OEM integrators must ensure that the end user has no manual
instructions to remove or install the LE920 module. Antennas used for this OEM module must
not exceed 3dBi gain for mobile and fixed operating configurations.
6.2.
GSM/WCDMA/LTE Antenna â PCB line Guidelines
Make sure that the transmission lineâs characteristic impedance is 50ohm.
Keep line on the PCB as short as possible since the antenna line loss shall be less than
around 0.3dB.
Line geometry should have uniform characteristics, constant cross section, avoid
meanders and abrupt curves.
Any kind of suitable geometry/structure can be used for implementing the printed
transmission line afferent the antenna.
If a Ground plane is required in line geometry, that plane has to be continuous and
sufficiently extended so the geometry can be as similar as possible to the related
canonical model.
Keep, if possible, at least one layer of the PCB used only for the Ground plane; If
possible, use this layer as reference Ground plane for the transmission line.
It is wise to surround (on both sides) of the PCB transmission line with Ground. Avoid
having other signal tracks facing directly the antenna line track.
Avoid crossing any un-shielded transmission line footprint with other tracks on
different layers.
The Ground surrounding the antenna line on PCB has to be strictly connected to the
main Ground plane by means of via holes (once per 2mm at least) placed close to the
ground edges facing line track.
Place EM noisy devices as far as possible from LE920 antenna line.
Keep the antenna line far away from the LE920 power supply lines.
If EM noisy devices are present on the PCB hosting the LE920, such as fast switching
ICs, take care of shielding them with a metal frame cover.
If EM noisy devices are not present around the line use of geometries like Micro strip
or Grounded Coplanar Waveguide are preferred since they typically ensure less
attenuation when compared to a Strip line having same length.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 43 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
6.3.
6.4.
GSM/WCDMA/LTE Antenna â Installation Guidelines
Install the antenna in a place covered by the GSM/WCDMA signal.
The Antenna must be installed to provide a separation distance of at least 20 cm
from all persons and must not be co-located or operating in conjunction with any
other antenna or transmitter;
Antenna must not be installed inside metal cases;
Antenna must be installed also according Antenna manufacturer instructions.
Antenna Diversity Requirements
This product is including an input for a second RX antenna to improve the radio sensitivity.
The function is called Antenna Diversity.
ANTENNA REQUIREMENTS
Frequency range
Bandwidth
Depending by frequency band(s) provided by the network operator, the
customer shall use the most suitable antenna for that/those band(s)
LE920-EU
LE920-NA
WCDMA band I(2100) : 250 MHz
WCDMA band II(1900) : 140 MHz
WCDMA band I(2100) : 250 MHz
WCDMA band IV(AWS) : 445 MHz
WCDMA band III(1800) : 170 MHz
WCDMA band IV(850) : 445 MHz
WCDMA band VIII(900) : 80 MHz
WCDMA band V(850) : 70 MHz
LTE Band I(2100) : 250 MHz
WDCMA band VI(800): 55MHzLTE
LTE band III(1800) : 170 MHz
Band I(2100) : 250 MHz
LTE Band VII(2600) : 190 MHz
LTE Band II(1900) : 140 MHz
LTE Band VIII(900) : 80 MHz
LTE Band IV(1700) : 445 MHz
LTE Band XX(800) : 71 MHz
LTE Band V (850) : 70 MHz
Band XVII(700) : 42 MHz
Impedance
VSWR recommended !$
When using the Telit LE920, since thereâs no antenna connector on the module, the antenna
must be connected to the LE920 antenna pad (AU9) by means of a transmission line
implemented on the PCB.
In the case that the antenna is not directly connected at the antenna pad of the LE920, then a
PCB line is required in order to connect with it or with its connector.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 44 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05The second Rx antenna should not be located in the close vicinity of main antenna. In order to
improve Diversity Gain, Isolation and reduce mutual interaction, the two antennas should be
located at the maximum reciprocal distance possible, taking into consideration the available
space into the application.
6.5.
GPS/GNSS Antenna Requirements
LE920 supports only passive antenna and includes an internal LNA inside (13.5dB gain typ.).
It is recommended to use antennas as follow:
An external passive antenna (GPS only)
An external passive antenna, GNSS pre-Filter
NOTE:
The external GNSS pre-Filter shall be required for GLONASS application.
GNSS pre-Filter requirement shall fulfill the following requirements.
z Source and Load Impedance = 50Ohm
z Insertion Loss (1575.42 â 1576.42MHz) = 1.4dB (Max)
z Insertion Loss (1565.42 â 1585.42MHz) = 1.4dB (Max)
z Insertion Loss (1597.5515 â 1605.886MHZ) = 2.0dB (Max)
WARNING:
The LE920 software is implemented differently depending on the configurations of an
external device. Please refer to the AT command User Guide in detail.
6.5.1.
Combined GPS/GNSS Antenna
The use of combined RF/GPS/GNSS antenna is NOT recommended. This solution could
generate extremely poor GPS/GNSS reception and also the combined antenna requires
additional diplexer and adds a loss in the RF route.
In addition, the combination of antennas requires an additional diplexer, which adds
significant power losses in the RF path.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 45 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
6.5.2.
Linear and Patch GPS/GNSS Antenna
Using this type of antenna introduces at least 3dB of loss if compared to a circularly polarized
(CP) antenna. Having a spherical gain response instead of a hemispherical gain response
could aggravate the multipath behaviour & create poor position accuracy.
6.5.3.
Front End Design Considerations
When using the Telit LE920, since thereâs no antenna connector on the module, the antenna
must be connected to the LE920 through the PCB with the antenna pad.
In the case that the antenna is not directly connected at the antenna pad of the LE920, then a
PCB line is required.
This line of transmission shall fulfill the following requirements:
Antenna Line on PCB Requirements
Characteristic Impedance
50Ohm
Max Attenuation
0.3dB
Coupling with other signals shall be avoided
Cold End (Ground Plane) of antenna shall be equipotential to the LE920 ground pads
Furthermore if the device is developed for the US and/or Canada market, it must comply with
the FCC and/or IC requirements.
This device is to be used only for mobile and fixed application.
6.5.4.
GPS/GNSS Antenna - PCB Line Guidelines
Ensure that the antenna line impedance is 50ohm.
Keep line on the PCB as short as possible to reduce the loss.
Antenna line must have uniform characteristics, constant cross section, avoid meanders
and abrupt curves.
Keep one layer of the PCB used only for the Ground plane; if possible.
Surround (on the sides, over and under) the antenna line on PCB with Ground. Avoid
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 46 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05x
6.5.5.
having other signal tracks directly facing the antenna line track.
The Ground around the antenna line on PCB has to be strictly connected to the main
Ground plane by placing vias once per 2mm at least.
Place EM noisy devices as far as possible from LE920 antenna line.
Keep the antenna line far away from the LE920 power supply lines.
If EM noisy devices are around the PCB hosting the LE920, such as fast switching ICs,
take care of shielding of antenna line by burying it inside the layers of PCB and
surround it with Ground planes; or shield it with a metal frame cover.
If you do not have EM noisy devices around the PCB of LE920, use a Micro strip line
on the superficial copper layer for the antenna line. The line attenuation will be lower
than a buried one.
GPS/GNSS Antenna â Installation Guidelines
The LE920, due to its sensitivity characteristics, is capable of performing a fix inside
buildings. (In any case the sensitivity could be affected by the building characteristics
i.e. shielding)
The Antenna must not be co-located or operating in conjunction with any other antenna
or transmitter.
Antenna shall not be installed inside metal cases.
Antenna shall be installed also according antenna manufacture instructions.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 47 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
7.
Logic Level Specifications
Where not specifically stated, all the interface circuits work at 1.8V CMOS logic levels.
The following table shows the logic level specifications used in the Telit LE920 interface
circuits:
NOTE:
Do not connect LE920âs digital logic signal directly to OEMâs digital logic signal of with
level higher than 2.7V for 1.8V CMOS signals.
For 1.8V CMOS signals:
Absolute Maximum Ratings - Not Functional
LE920
Parameter
Min
Max
Input level on any
-0.3V
+2.16V
digital pin when on
Input voltage on
-0.3V
+2.16 V
analog pins when on
Operating Range - Interface levels (1.8V CMOS)
LE920
Level
Min
Max
Input high level
1.5V
2.1V
Input low level
Output high level
Output low level
-0.3V
1.35V
0V
0.5V
1.8V
0.45V
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 48 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
8.
USB Port
The LE920 module includes a Universal Serial Bus (USB) transceiver, which operates at
USB low-speed (1.5Mbits/sec), USB full-speed (12Mbits/sec) and USB high-speed
(480Mbits/sec).
It is compliant with the USB 2.0 specification and can be used for diagnostic monitoring,
control and data transfers.
The USB_DPLUS and USB_DMINUS signals have a clock rate of 480MHz. The signal
traces should be routed carefully. Trace lengths, number of vias and capacitive loading should
be minimized. The impedance value should be as close as possible to 90 Ohms differential.
The table below describes the USB interface signals:
USB_VBUS
LE920
Pad No.
A18
USB_D-
F19
USB D+
D19
Signal
Usage
Power sense for the internal USB transceiver .
Minus (-) line of the differential, bi-directional USB signal to/from the
peripheral device
Plus (+) line of the differential, bi-directional USB signal to/from the
peripheral device
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 49 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
9.
Serial Ports
The serial port on the Telit LE920 is the interface between the module and OEM hardware.
Two serial ports are available on the module:
MODEM SERIAL PORT 1(Main)
MODEM SERIAL PORT 2 (Auxiliary) -TBD
Several configurations can be designed for the serial port on the OEM hardware.
The most common are:
RS232 PC com port;
Microcontroller UART @ 1.8V (Universal Asynchronous Receive Transmit) ;
Microcontroller UART @ 5V or other voltages different from 1.8V.
Depending on the type of serial port on the OEM hardware, a level translator circuit may be
needed to make the system work. The only configuration that does not need a level translation
is the 1.8V UART.
The serial port 1 on LE920 is a +1.8V UART with all the 7 RS232 signals. It differs from the
PC-RS232 in signal polarity (RS232 is reversed) and levels.
The Serial port 2 is a +1.8V Auxiliary UART.
The levels for LE920 UART are the CMOS levels:
Absolute Maximum Ratings -Not Functional
LE920
Parameter
Min
Max
Input level on any
-0.3V
+2.16 V
digital pin when on
Input voltage on
-0.3V
+2.16 V
analog pins when on
Operating Range - Interface levels
LE920
Level
Min
Max
Input high level
1.5V
2.1V
Input low level
Output high level
Output low level
-0.3V
1.35V
0V
0.5V
1.8V
0.45V
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 50 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
9.1.
Modem Serial Port 1
Serial port 1 on the LE920 is a +1.8V UART with all 7 RS232 signals.
It differs from the PC-RS232 in the signal polarity (RS232 is reversed) and levels.
RS232
Pin
Number
LE920
Pad Number
Signal
DCD dcd_uart
RXD Tx_uart
TXD Rx_uart
DTR dtr_uart
GND
DSR dsr_uart
RTS rts_uart
CTS cts_uart
RI ri_uart
Name
Data Carrier
Detect
Transmit line
AF19
*see Note
Receive line
AH19
*see Note
Data Terminal
AC18
Ready
A6, A12, B13, B15âŚ. Ground
AE18
AG18
Data Set Ready
AA18
Request to Send
AK19
Clear to Send
AJ18
Ring Indicator
Usage
Output from the LE920 that indicates the carrier
presence
Output transmit line of the LE920 UART
Input receive of the LE920 UART
Input to the LE920 that controls the DTE READY
condition
ground
Output from the LE920 that indicates the module is
ready
Input to the LE920 that controls the Hardware flow
control
Output from the LE920 that controls the Hardware flow
control
Output from the LE920 that indicates the Incoming call
condition
NOTE:
In order to avoid a back powering effect it is recommended to avoid having any HIGH logic
level signal applied to the digital pins of the module when is powered OFF or during an
ON/OFF transition.
TIP:
For minimum implementation, only the TXD and RXD lines can be connected, the other lines
can be left open provided a software flow control is implemented.
NOTE:
According to V.24, RX/TX signal names are referred to the application side, therefore on the
LE920 side these signal are on the opposite direction: TXD on the application side will be
connected to the receive line (here named TXD/ rx_uart ) of the LE920 serial port and vice
versa for RX.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 51 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
9.2.
Modem Serial Port 2
Serial port 2 on the LE920 is a +1.8V UART with only the RX and TX signals.
The signals of the LE920 serial port are:
PAD
Signal
I/O
Function
Type
AB19 TXD_AUX O Auxiliary UART (TX Data to DTE) 1.8V
Auxiliary UART (RX Data to DTE) 1.8V
AD19 RXD_AUX I
COMMENT
NOTE:
In order to avoid a back powering effect it is recommended to avoid having any HIGH logic
level signal applied to the digital pins of the module when is powered OFF or during an
ON/OFF transition.
9.3.
RS232 Level Translation
In order to interface the Telit LE920 with a PC com port or a RS232 (EIA/TIA-232)
application a level translator is required. This level translator must:
Invert the electrical signal in both directions;
Change the level from 0/1.8V to +15/-15V.
Actually, the RS232 UART 16450, 16550, 16650 & 16750 chipsets accept signals with lower
levels on the RS232 side (EIA/TIA-562), allowing a lower voltage-multiplying ratio on the
level translator. Note that the negative signal voltage must be less than 0V and hence some
sort of level translation is always required.
The simplest way to translate the levels and invert the signal is by using a single chip level
translator. There are a multitude of them, differing in the number of drivers and receivers and
in the levels (be sure to get a true RS232 level translator not a RS485 or other standards).
By convention the driver is the level translator from the 0-1.8V UART to the RS232 level.
The receiver is the translator from the RS232 level to 0-1.8V UART.
In order to translate the whole set of control lines of the UART you will need:
5 drivers
3 receivers
NOTE:
The digital input lines working at 1.8V CMOS have an absolute maximum input voltage of
2.7V; therefore the level translator IC shall not be powered by the +3.8V supply of the
module. Instead, it must be powered from a +1.8V (dedicated) power supply.
This is because in this way the level translator IC outputs on the module side (i.e. LE920
inputs) will work at +3.8V interface levels, damaging the module inputs.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 52 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05An example of RS232 level adaption circuitry could be accomplished using a MAXIM
transceiver (MAX218).
In this case the chipset is capable of translating directly from 1.8V to the RS232 levels
(Example on 4 signals only).
NOTE:
In this case has to be taken in account the length of the lines on the application to avoid
problems in case of High-speed rates on RS232.
The RS232 serial port lines are usually connected to a DB9 connector with the following
layout: signal names and directions are named and defined from the DTE point of view
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 53 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
10. Audio Section Overview
The LE920 module support digital audio interface.
10.1.
Digital Audio
LE920 module can be connected to external codec through digital interface.
The product is providing one Digital Audio Interface (DVI) on the following Pins:
PAD
Signal
I/O
Function
D11
DVI_WA0
I/O
Digital Audio Interface (WA0)
C8
DVI_RX
Digital Audio Interface (RX)
D9
DVI_TX
Digital Audio Interface (TX)
C10
DVI_CLK
I/O
Digital Audio Interface (CLK)
Type
B-PD
1.8V
B-PD
1.8V
B-PD
1.8V
B-PD
1.8V
COMMENT
PCM_SYNC
PCM_DIN
PCM_DOUT
PCM_CLK
LE920 DVI supports PCM master 2048khz short frame
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 54 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 55 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
11. General Purpose I/O
The general-purpose I/O pads can be configured to act in three different ways:
input
output
alternate function (internally controlled)
Input pads can only be read and report the digital value (high or low) present on the pad at the
read time; output pads can only be written or queried and set the value of the pad output; an
alternate function pad is internally controlled by the LE920 firmware and acts depending on
the function implemented.
The following GPIOs are available on the LE920.
PAD
Signal
I/O
Function
F9
GPIO_01
I/O Configurable GPIO
E10
GPIO_02
I/O
F11
GPIO_03
I/O
E12
GPIO_04
I/O
F13
GPIO_05
I/O
E14
GPIO_06
I/O
R18
GPIO_07
I/O
S19
GPIO_08
I/O Configurable GPIO
U19
GPIO_09
I/O Configurable GPIO
W19
GPIO_10
I/O Configurable GPIO
Configurable GPIO
Configurable GPIO
Configurable GPIO
Configurable GPIO
Configurable GPIO
Configurable GPIO
Type
BH-PD(*)
1.8V
BH-PD(*)
1.8V
BH-PD(*)
1.8V
BH-PD(*)
1.8V
BH-PD(*)
1.8V
BH-PD(*)
1.8V
BH-PD(*)
1.8V
BH-PD(*)
1.8V
BH-PD(*)
1.8V
BH-PD(*)
1.8V
Drive Strength
2 mA
2 mA
2 mA
2 mA
2 mA
2 mA
2 mA
2 mA
2 mA
2 mA
(*) BH-PD - Bidirectional digital with CMOS input; High-voltage tolerant; Contains an
internal pull-down device.
NOTE:
In order to avoid a back powering effect it is recommended to avoid having any HIGH logic
level signal applied to the digital pins of the module when is powered OFF or during an
ON/OFF transition.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 56 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
11.1.
Logic Level Specifications
Where not specifically stated, all the interface circuits work at 1.8V CMOS logic levels.
The following table shows the logic level specifications used in the LE920 interface circuits:
For 1,8V signals:
Absolute Maximum Ratings -Not Functional
LE920
Parameter
Min
Max
Input level on any
-0.3V
+2.16 V
digital pin when on
Input voltage on
-0.3V
+2.16 V
analog pins when on
Operating Range - Interface levels (1.8V CMOS)
LE920
Level
Min
Max
Input high level
1.5V
2.1V
Input low level
Output high level
Output low level
11.2.
-0.3V
1.35V
0V
0.5V
1.8V
0.45V
Using a GPIO Pad as Input
The GPIO pads, when used as inputs, can be connected to a digital output of another device
and report its status, provided this device has interface levels compatible with the 1.8V
CMOS levels of the GPIO.
If the digital output of the device is connected with the GPIO input, the pad has interface
levels different from the 1.8V CMOS. It can be buffered with an open collector transistor with
%'?Q -up resistor to 1.8V.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 57 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
11.3.
Using a GPIO Pad as Output
The GPIO pads, when used as outputs, can drive 1.8V CMOS digital devices or compatible
hardware. When set as outputs, the pads have a push-pull output and therefore the pull-up
resistor may be omitted.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 58 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
11.4.
11.4.1.
Using the Temperature Monitor Function
Short Description
The Temperature Monitor is a function of the module that permits to control its internal
temperature and if properly set (see the #TEMPMON command on AT Interface guide) it
raises to High Logic level a GPIO when the maximum temperature is reached.
11.5.
Indication of Network Service Availability
The STAT_LED pin status shows information on the network service availability and call
status. In the LE920 modules, the STAT_LED usually needs an external transistor to drive an
external LED. Because of the above, the status indicated in the following table is reversed
with respect to the pin status:
LED status
Permanently off
Fast blinking
(Period 1s, Ton 0,5s)
Slow blinking
(Period 3s, Ton 0,3s)
Permanently on
Device Status
Device off
Net search / Not registered /
turning off
Registered full service
a call is active
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 59 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
11.6.
RTC Bypass Out
The VRTC pin brings out the Real Time Clock supply, which is separate from the rest of the
digital part, allowing having only RTC going on when all the other parts of the device are off.
To this power output a backup capacitor can be added in order to increase the RTC autonomy
during power off of the battery.
NOTE:
NO devices must be powered from this pin.
11.7.
VAUX Power Output
A regulated power supply output is provided in order to supply small devices from the
module. This output is active when the module is ON and goes OFF when the module is shut
down. The operating range characteristics of the supply are:
Operating Range â VAUX power supply
Min
Typical
Max
1.75V
1.85V
Output voltage
1.80V
Output current
100mA
Output bypass capacitor
(Inside the module)
1
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 60 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
12. ADC section
12.1.
12.1.1.
ADC Converter
Description
The on board ADCs are 8-bit converters. They are able to read a voltage level in the range of
0-2 volts applied on the ADC pin input and store and convert it into 8 bit word.
Input Voltage range
AD conversion
Resolution
Min
Max
1.7
< 6.6
Units
Volt
bits
mV
The LE920 module provides 3 Analog to Digital Converters.
12.1.2.
Using ADC Converter
An AT command is available to use the ADC function.
The command is AT#ADC=1,2. The read value is expressed in mV
Refer to SW User Guide or AT Commands Reference Guide for the full description of this
function.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 61 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
13. Mounting the module on your board
13.1.
General
The LE920 modules have been designed in order to be compliant with a standard lead-free
SMT process.Module
13.2.
Finishing & Dimensions
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 62 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
13.3.
Recommended foot print for the application
198 pads
Top View
In order to easily rework the LE920 it is suggested to consider on the application having a 1.5
mm placement inhibit area around the module.
It is also suggested, as a common rule for an SMT component, to avoid having a mechanical
part of the application in direct contact with the module.
NOTE:
In the customer application, the region under WIRING INHIBIT (see figure) must be clear
from signal or ground paths.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 63 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
13.4.
Stencil
Stencilâs apertures layout can be the same as the recommended footprint (1:1). A suggested
thickness of stencil foil is greater than 120 Îźm.
13.5.
PCB Pad Design
Non solder mask defined (NSMD) type is recommended for the solder pads on the PCB.
Copper pad
PCB
Solder mask
Copper pad
PCB
Solder Mask Defined
13.6.
Non Solder Mask Defined
Recommendations for PCB Pad Dimensions (mm)
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 64 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05It is not recommended to place via or micro-via not covered by solder resist in an area of 0,3
mm around the pads unless it carries the same signal of the pad itself (see following figure).
Holes in pad are allowed only for blind holes and not for through holes.
Recommendations for PCB Pad Surfaces:
Finish
Electro-less Ni / Immersion Au
Layer thickness (um)
3 â7 / 0.05 â 0.15
Properties
good solder ability protection,
high shear force values
The PCB must be able to resist the higher temperatures which are occurring at the lead-free
process. This issue should be discussed with the PCB-supplier. Generally, the wettability of
tin-lead solder paste on the described surface plating is better compared to lead-free solder
paste.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 65 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
13.7.
Solder Paste
Solder Paste
Lead free
Sn/Ag/Cu
We recommend using only âno cleanâ solder paste in order to avoid the cleaning of the
modules after assembly.
13.7.1.
Solder Reflow
Recommended solder reflow profile:
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 66 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05Profile Feature
Average ramp-up rate (TL to TP)
Preheat
â Temperature Min (Tsmin)
â Temperature Max (Tsmax)
â Time (min to max) (ts)
Tsmax to TL
â Ramp-up Rate
Time maintained above:
â Temperature (TL)
â Time (tL)
Peak Temperature (Tp)
Time within 5°C of actual Peak
Temperature (tp)
Ramp-down Rate
Time 25°C to Peak Temperature
Pb-Free Assembly
3°C/second max
150°C
200°C
60-180 seconds
3°C/second max
217°C
60-150 seconds
245 +0/-5°C
10-30 seconds
6°C/second max.
8 minutes max.
NOTE:
All temperatures refer to topside of the package, measured on the package body surface.
WARNIG:
The LE920 module withstands one reflow process only.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 67 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
14. Application guide
14.1.
Debug of the LE920 in production
To test and debug the mounting of LE920, we strongly recommend to foresee test pads on the
host PCB, in order to check the connection between the LE920 itself and the application and
to test the performance of the module connecting it with an external computer. Depending on
the customer application, these pads include, but are not limited to the following signals:
TXD
RXD
ON/OFF
RESET
GND
VBATT
TX_TRACE
RX_TRACE
PWRMON
USB_VBUS
USB_D+
USB_D-
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 68 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
14.2.
Bypass capacitor on Power supplies
When a sudden voltage is asserted to or cut from the power supplies, the steep transition
makes some reactions such as the overshoot and undershoot.
This abrupt voltage transition can affect the device not to work or make it malfunction.
The bypass capacitors are needed to alleviate this behavior and it can be affected differently
according to the various applications. The customers have to pay special attention to this
when they design their application board.
The length and width of the power lines need to be considered carefully and the capacitance
of the capacitors need to be selected accordingly.
The capacitor will also avoid the ripple of the power supplies and the switching noise caused
in TDMA system like GSM.
Specially the suitable bypass capacitor must be mounted on the Vbatt & Vbatt_PA (Pads
AP17,AP19,AR18,AS17,AS19,AT18,AU17,AU19) and USB_VBUS (Pad A18) lines in the
application board.
The recommended values can be presented as:
100uF for Vbatt
10uF for USB_VBUS
The customers still have to consider that the capacitance mainly depends on the conditions of
their application board.
Generally more capacitance is required as the power line is longer.
14.3.
SIM interface
The resistor value on SIMIO pulled up to SIMVCC should be defined accordingly in order to
be compliant to 3GPP specification.
6.8kohm resistor can be recommended but it may depend on the application design.
Refer to the following document for the detail:
Telit_SIM_interface_and ESD_protection_Application_note_r1
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 69 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
14.4.
EMC recommendations (TBD)
LE920 signals are provided by some EMC protections. In any case the accepted levels are
different on the pins. The characteristics are described in the following Table:
Pad
Signal
AP17,AP19,
AR18,AS17, VBATT_PA
AS19,AT18, And VBATT
AU17,AU19
I/O
Function
Power Supply
Contact
Air
Main power supply
Âą 8KV
Âą 15KV
Âą 8KV
Âą 8KV
Âą 8KV
Âą 8KV
Âą 15KV
Âą 15KV
Âą 15KV
Âą 15KV
A8
B11
B9
A10
SIMVCC
SIMRST
SIMIO
SIMCLK
I/O
SIM Card Interface
External SIM signal â Power supply for the SIM
External SIM signal â Reset
External SIM signal - Data I/O
External SIM signal â Clock
Miscellaneous Functions
A18
USB_VBUS
AI
Power sense for the internal USB transceiver
Âą 8KV
Âą 15KV
P17
VAUX
Âą 8KV
Âą 15KV
AS1
ON/OFF
Âą 8KV
Âą 15KV
AP1
F17
RESET
VRTC
AO
Power output for external accessories
Input command for switching power ON or OFF
(toggle command).
Reset input
Power supply for RTC block
Antenna
Âą 8KV
Âą 8KV
Âą 15KV
Âą 15KV
Antenna pad for Rosenberger connector
Âą 8KV
Âą 15KV
AD1,AU9,S1 Antenna Pad
AI
All other pins have the following characteristics:
HBM JESD22-A114-B Âą 2000 V
CDM JESD22-C101-C Âą 500 V
The Board to Board connector has to be considered as NO TOUCH area.
Appropriate series resistors have to be considered to protect the input lines from overvoltage.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 70 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
14.5.
Download and Debug Port
One of the following options should be chosen in the design of host system in order to
download or upgrade the Telitâs software and debug LE920 when LE920 is already mounted
on a host system.
Users who use both of UART and USB interfaces to communicate LE920
Must implement a download method in a host system for upgrading LE920 when itâs
mounted.
Users who use USB interface only to communicate LE920
Must arrange UART port in a host system for debugging or upgrading LE920 when itâs
mounted.
Users who use UART interface only to communicate LE920
Must arrange USB port in a host system for debugging or upgrading LE920 when itâs
mounted.
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 71 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
15. Packing system
The Telit LE920 is packaged on trays. Each tray contains 20 pieces as shown in the following
picture:
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 72 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
15.1.
Tray Drawing
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 73 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05WARNIG:
These trays can withstand a maximum temperature of 65Í .
15.2.
Moisture Sensibility
The LE920 is a Moisture Sensitive Device level 3, in accordance with standard IPC/JEDEC JSTD-020. Observe all of the requirements for using this kind of components.
Calculated shelf life in sealed bag: 4 months at <40°C and <90% relative humidity (RH).
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 74 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
16. Safety Recommendations
READ CAREFULLY
Be sure about that the use of this product is allowed in your country and in the environment
required. The use of this product may be dangerous and has to be avoided in the following
areas:
Where it can interfere with other electronic devices in environments such as
hospitals, airports, aircrafts, etc.
Where there is risk of explosion such as gasoline stations, oil refineries, etc.
It is responsibility of the user to enforce the country regulation and the specific environment
regulation.
Do not disassemble the product; any mark of tampering will compromise the warranty
validity.
We recommend following the instructions of the hardware user guides for a correct wiring of
the product. The product has to be supplied with a stabilized voltage source and the wiring
has to be conforming to the security and fire prevention regulations.
The product has to be handled with care, avoiding any contact with the pins because
electrostatic discharges may damage the product itself. Same cautions have to be taken for the
SIM, checking carefully the instruction for its use. Do not insert or remove the SIM when the
product is in power saving mode.
The system integrator is responsible of the functioning of the final product; therefore, care has
to be taken to the external components of the module, as well as of any project or installation
issue, because the risk of disturbing the GSM network or external devices or having impact
on the security. Should there be any doubt, please refer to the technical documentation and the
regulations in force.
Every module has to be equipped with a proper antenna with specific characteristics. The
antenna has to be installed with care in order to avoid any interference with other electronic
devices and has to be installed with the guarantee of a minimum 20 cm distance from the
body. In case of this requirement cannot be satisfied, the system integrator has to assess the
final product against the SAR regulation.
The European Community provides some Directives for the electronic equipments introduced
on the market. All the relevant information are available on the European Community website:
http://europa.eu.int/comm/enterprise/rtte/dir99-5.htm
The text of the Directive 99/05 regarding telecommunication equipments is available, while
the applicable Directives (Low Voltage and EMC) are available at:
http://europa.eu.int/comm/enterprise/rtte/dir99-5.htm
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 75 of 76
LE920 Hardware User Guide
1vv0301026 Rev.0 - draft4 â 2013-05-
17. Document History
Revision
0-draft1
0-draft2
Date
2012-10-03
2012-12-11
0-draft3
0-draft4
2013-03-12
2013-05-21
Changes
First issue
- Remove SIM2 interface
- Remove external GPS LNA support
Updated pin-out
- Update DVI
- Adding Current consumption
- Adding SHDN_N section
- Update Mechanical drawings
FCC Warning
This equipment has been tested and found to comply with the limits for a class B digital device,
pursuant to part 15 of the FCC rules. These limits are designed to provide to provide reasonable
protection against harmful interference in a residential installation. This equipment generates, uses
and can radiate radio frequency energy and, if not installed and used in accordance with the
installation, may cause harmful interference to radio communication. However, there is no guarantee
that interference
will not occur in a particular installation. if this equipment does cause harmful interference to radio
or television reception, which can be determined by turning the equipment off and on, the user is
encouraged to try to correct the interference by one or more of the following measures:
-Reorient or relocate the receiving antenna
-Increase the separation between the equipment and receiver
-Connect the equipment into an outlet on a circuit different from that to which the receiver is
connected
-Consult the dealer or an experienced radio / TV technician for help
You are cautioned that changes or modifications not expressly approved by the party responsible for
compliance could void your authority to operate the equipment.
This device complies with part 15 of the FCC rules. Operation is subject to the following two
conditions
(1) This device may not cause harmful interference and
(2) this device must accept any interference received, including interference that may cause undesired
operation.
Labelďź
âContains FCC IDďźRI7LE920NA
âContains ICďź5131A-LE920NA
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 76 of 76
Source Exif Data:
File Type : PDF File Type Extension : pdf MIME Type : application/pdf PDF Version : 1.5 Linearized : Yes Author : federicovi Comments : Company : Telit Wireless Solutions Inc Create Date : 2013:09:24 11:32:08+08:00 Modify Date : 2013:09:24 11:32:08+08:00 Source Modified : D:20130522122308 Subject : HW User Guide Template Tag New Review Cycle : XMP Toolkit : Adobe XMP Core 4.2.1-c043 52.372728, 2009/01/18-15:08:04 Metadata Date : 2013:09:24 11:31:57+08:00 Creator Tool : Acrobat PDFMaker 10.1 for Word Document ID : uuid:ec118bff-0698-4e3f-9780-4364398a2eb3 Instance ID : uuid:0f928774-42a9-4838-85bc-c20758e9cdcd Format : application/pdf Title : HW User Guide Template Description : HW User Guide Template Creator : federicovi Producer : Acrobat Distiller 9.3.3 (Windows) Keywords : Headline : HW User Guide Template Page Count : 76EXIF Metadata provided by EXIF.tools