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

LLE920 HHardware User Guide 1vv0301026 Rev.0 - draft4 – 2013-05-21 ((Preliminary)
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 2 of 76 APPLICABILITY TABLE PRODUCT LE920--EU LE920--NA
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 3 of 76 SPECIFICATIONS 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 4 of 76 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 © Telit Communications S.p.A. 2012.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 5 of 76 Contents 1. 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 2. 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. Operating Frequency ................................................................................................. 15 2.5.1.1. WCDMA1700 – 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 3. LE920 Module Connections .................................................................................. 17 3.1. PIN-OUT ..................................................................................................................... 17 3.1.1. LGA Pads Layout ............................................................................................................ 24 4. 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
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 6 of 76 4.3.2. Hardware Shutdown ...................................................................................................... 29 4.3.3. Hardware Unconditional Restart ................................................................................... 30 4.3.4. Hardware Unconditional Shutdown ............................................................................... 31 4.4. Summary of Turning ON and OFF the module .......................................................... 32 5. Power Supply ....................................................................................................... 33 5.1. Power Supply Requirements ..................................................................................... 33 5.2. General Design Rules ................................................................................................ 35 5.2.1. 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 6. Antenna(s) ........................................................................................................... 42 6.1. GSM/WCDMA/LTE Antenna Requirements ............................................................... 42 6.2. GSM/WCDMA/LTE Antenna – PCB line Guidelines ................................................... 43 6.3. GSM/WCDMA/LTE Antenna – 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 – 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
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 7 of 76 10.1. Digital Audio ........................................................................................................... 54 11. 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. ADC Converter ........................................................................................................ 61 12.1.1. Description ..................................................................................................................... 61 12.1.2. Using ADC Converter ..................................................................................................... 61 13. 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)............................................... 6413.7. Solder Paste ........................................................................................................... 6613.7.1. Solder Reflow ................................................................................................................. 66 14. 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
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 8 of 76 15. Packing system ................................................................................................. 72 15.1. Tray Drawing........................................................................................................... 73 15.2. Moisture Sensibility ................................................................................................ 74 16. Safety Recommendations .................................................................................. 75 17. Document History ............................................................................................. 76
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 9 of 76 1. Introduction 1.1. 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 “LE920” 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 Telit’s Technical Support Center (TTSC) at: TS-EMEA@telit.com TS-NORTHAMERICA@telit.com TS-LATINAMERICA@telit.com TS-APAC@telit.comAlternatively, 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 Telit’s 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 10 of 76 1.4. Document Organization This document contains the following chapters: Chapter 1: “Introduction” provides a scope for this document, target audience, contact and support information, and text conventions. Chapter 2: “General Product Description” gives an overview of the features of the product. Chapter 3: “LE920 Module Connections” deals with the pin out configuration and layout. Chapter 4: “Hardware Commands” How to control the module via hardware Chapter 5: “Power Supply” deals on supply and consumption. Chapter 6: “Antenna” The antenna connection and board layout design are the most important parts in the full product design Chapter 7: “Logic Level specifications” Specific values adopted in the implementation of logic levels for this module. Chapter 8: “USB Port” Chapter 9: “Serial Ports” Chapter 10: “Audio Section Overview” Chapter 11: “General Purpose I/O” How the general purpose I/O pads can be configured. Chapter 12 “DAC and ADC Section” Deals with these two kind of converters. Chapter 13: “Mounting the module on your board” Chapter 14: “Application Guides” Chapter 15: “Packing System” Chapter 16: “Conformity Assessments” Chapter 17: “Safety Recommendations” Chapter 18: “Document History”
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 11 of 76 1.5. Text Conventions Danger – This information MUST be followed or catastrophic equipment failure or bodily injury may occur. Caution or Warning – 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 – 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 x LE920-EU/NA Product Description, 80407ST10118A x LE920-EU/NA AT command reference guide, 80407ST10116A x Telit EVK2 User Guide, 1vv0300704
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 12 of 76 2. General Product Description 2.1. 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 13 of 76 2.2. LE920 Mechanical Dimensions The Telit LE920 module overall dimensions are:  Length: 34 mm  Width: 40 mm  Thickness: 2.9 mm 2.3. Weight The module weight of LE920-EU/NA is about 9.0 gram.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 14 of 76 2.4. Environmental requirements 2.4.1. Temperature range Note Operating Temperature Range –20°C ~ +55°C The module is fully functional (*) in all the temperature range, and it fully meets the ETSI specifications. –40°C ~ +85°C The module is fully functional (*) in all the temperature range. Temperatures outside of the range –20°C ÷ +55°C might slightly deviate from ETSI specifications. Storage and non-operating Temperature Range –40°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).
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 15 of 76 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 MHzEGSM900 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 WCDMA2100 – B1 (LE920 both models) 1920 ~ 1980 2110 ~ 2170Tx: 9612 ~ 9888 Rx: 10562 ~ 10838 190MHzWCDMA1900 – B2 (LE920-NA only) 1850 ~ 1910 1930 ~ 1990 Tx: 9262 ~ 9538 Rx: 9662 ~ 9938 80MHz WCDMA1800 – B3 (LE920-EU only) 1710 ~ 1785 1805 ~ 1880 Tx: 937 ~ 1288 Rx: 1162 ~ 1513 95MHz WCDMA1700 – B4 (LE920-NA only) 1710 ~ 1755 2110 ~ 2155 Tx: 1312 ~ 1513 Rx: 9662 ~ 9938 400 MHz WCDMA850 – B5 (LE920-NA only) 824 ~ 849 869 ~ 894 Tx: 4132 ~ 4233 Rx: 4357 ~ 4458 45MHz WCDMA800 – B6 (LE920-NA only) 830 ~ 840 875 ~ 885 Tx: 4162 ~ 4188 Rx: 4387 ~ 4413 45MHz WCDMA900 – B8 (LE920-EU only) 880 ~ 915 925 ~ 960 Tx: 2712 ~ 2863 Rx: 2937 ~ 3088 45MHz LTE2100 – B1 (LE920 both models) 1920 ~ 1980 2110 ~ 2170 Tx: 18000 ~ 18599 Rx: 0 ~ 599 190MHz
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 16 of 76 LTE1900 – B2 (LE920-NA only) 1850 ~ 1910 1930 ~ 1990 Tx: 18600 ~ 19199 Rx: 600 ~ 1199 80MHz LTE1800 – B3 (LE920-EU only) 1710 ~ 1785 1805 ~ 1880 Tx: 19200 ~ 19949 Rx: 1200 ~ 1949 95MHz LTE1700 – B4 (LE920-NA only) 1710~ 1755 2110 ~ 2155 Tx: 19950 ~ 20399 Rx: 1950 ~ 2399 400MHz LTE850 – B5 (LE920-NA only) 824 ~ 849 869 ~ 894 Tx: 20400 ~ 20649 Rx: 2400 ~ 2649 45MHz LTE2600 – B7 (LE920-EU only) 2500 ~ 2570 2620 ~ 2690 Tx: 20750 ~ 21449 Rx: 2750 ~ 3449 120MHz LTE900 – B8 (LE920-EU only) 880 ~ 915 925 ~ 960 Tx: 21450 ~ 21799 Rx: 3450 ~ 3799 45MHz LTE700 – B17 (LE920-NA only) 704 ~ 716 734 ~ 746 Tx: 23730 ~ 23849 Rx: 5730 ~ 5849 30MHzLTE800 – B20 (LE920-EU only) 832 ~ 862 791 ~ 821 Tx: 24150 ~ 24449 Rx: 6150 ~ 6449 -41MHz
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 17 of 76 3. LE920 Module Connections 3.1. PIN-OUT PAD Signal I/O Function Type COMMENT USB HS 2.0 Communication Port D19 USB_D+ I/O USB differential Data(+) F19 USB_D- I/O USB differential Data(+) A18 USB_VBUS AI Power sense for the internal USB transceiver Power Asynchronous UART – Prog. / data +HW Flow Control AH19 C103/TXD I Serial data input (TXD) from DTE 1.8V AF19 C104/RXD O Serial data output to DTE 1.8V AC18 C108/DTR I Input for Data terminal ready signal (DTR) from DTE 1.8V AA18 C105/RTS I Input for Request to send signal (RTS) from DTE 1.8V AK19 C106/CTS O Output for Clear to send signal (CTS) to DTE 1.8V AE18 C109/DCD O Output for Data carrier detect signal (DCD) to DTE 1.8V AG18 C107/DSR O Output for Data set ready signal (DSR) to DTE 1.8V AJ18 C125/RING O Output for Ring indicator signal (RI) to DTE 1.8V Asynchronous Auxiliary UART AB19 TXD_AUX O Auxillary UART (TX Data to DTE) 1.8V AD19 RXD_AUX I Auxillary UART (RX Data from DTE) 1.8V SIM Card Interface 1 A10 SIMCLK1 O External SIM signal – Clock 1.8/2.85V B11 SIMRST1 O External SIM signal – Reset 1.8/2.85V B9 SIMIO1 I/O External SIM signal - Data I/O 1.8/2.85V B7 SIMIN1 I External SIM signal - Presence (active low) 1.8V A8 SIMVCC1 - External SIM signal – Power supply for the SIM 1.8/2.85V Audio B5 EAR1_MT+ AO Earphone signal output1, phase + Audio A4 EAR1_MT- AO Earphone signal output1, phase - Audio B3 MIC1_MT+ AI Mic signal input1, phase + Audio A2 MIC1_MT- AI Mic signal input1, phase - Audio E2 EAR2_MT+ AO Earphone signal output2, phase + Audio D1 EAR2_MT- AO Earphone signal output2, phase - Audio C2 MIC2_MT+ AI Mic signal input2, phase + Audio B1 MIC2_MT- AI Mic signal input2, phase - Audio Digital Voice interface (DVI) D11 DVI_WA0 O Digital Voice interface (WA0 master output) 1.8V C8 DVI_RX I Digital Voice interface (RX) 1.8V D9 DVI_TX O Digital Voice interface (TX) 1.8V
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 18 of 76 PAD Signal I/O Function Type COMMENTC10 DVI_CLK O Digital Voice interface (CLK master output) 1.8V Digital I/O F9 GPIO_01 I/O GPIO_01 1.8V E10 GPIO_02 I/O GPIO_02 1.8V F11 GPIO_03 I/O GPIO_03 1.8V E12 GPIO_04 I/O GPIO_04 1.8V F13 GPIO_05 I/O GPIO_05 1.8V E14 GPIO_06 I/O GPIO_06 1.8V R18 GPIO_07 I/O GPIO_07 1.8V S19 GPIO_08 I/O GPIO_08 1.8V U19 GPIO_09 I/O GPIO_09 1.8V W19 GPIO_10 I/O GPIO_10 1.8V RF Section AD1 Antenna I/O GSM/EDGE/UMTS/LTE Antenna (50 Ohm) RF AU9 ANT_DIV I UMTS/LTE Antenna Diversity Input (50 Ohm) RF GPS Section S1 ANT_GPS I GPS Antenna (50 Ohm) RF Miscellaneous Function AP1 RESET# I Reset Input Active Low AS1 ON_OFF# I Input Command for Power ON Active Low AN12 SHDN_N I Unconditional Shut down Input Active Low F17 VRTC AI VRTC Backup Capacitor Power To be used to back up the RTC section P17 VAUX/PWRMON O Supply Output for External Accessories / Power ON Monitor 1.8V D5 ADC_IN1 AI Analog/Digital Converter Input 1 Analog E6 ADC_IN2 AI Analog/Digital Converter Input 2 Analog F7 ADC_IN3 AI Analog/Digital Converter Input 3 Analog AU3 STAT_LED O Status Indicator LED 1.8V AN10 SW_RDY O Indicates that the boot sequence completed successfully 1.8V Power Supply AP17 VBATT - Main Power Supply (Digital Section) Power AP19 VBATT - Main Power Supply (Digital Section) Power AR18 VBATT - Main Power Supply (Digital Section) Power AS17 VBATT_PA - Main Power Supply (RF Transmit Power Section) Power AS19 VBATT_PA - Main Power Supply (RF Transmit Power Section) Power AT18 VBATT_PA - Main Power Supply (RF Transmit Power Section) Power AU17 VBATT_PA - Main Power Supply (RF Transmit Power Section) Power AU19 VBATT_PA - Main Power Supply (RF Transmit Power Section) Power A6 GND - Ground
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 19 of 76 PAD Signal I/O Function Type COMMENTA12 GND - Ground B13 GND - Ground B15 GND - Ground B17 GND - Ground C4 GND - Ground C6 GND - Ground D3 GND - Ground D7 GND - Ground E18 GND - Ground F1 GND - Ground G18 GND - Ground H19 GND - Ground M1 GND - Ground N2 GND - Ground P1 GND - Ground P3 GND - Ground R2 GND Ground T2 GND Ground T18 GND - Ground U1 GND - Ground V18 GND - Ground W1 GND - Ground X2 GND - Ground X18 GND - Ground Y1 GND - Ground Y19 GND Ground AA2 GND - Ground AB1 GND - Ground AC2 GND - Ground AE2 GND - Ground AF1 GND - Ground AG2 GND - Ground AH1 GND - Ground AJ2 GND - Ground AK1 GND - Ground AK17 GND - Ground AL18 GND - Ground AM17 GND - Ground AM19 GND - Ground AN16 GND - Ground AN18 GND - Ground
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 20 of 76 PAD Signal I/O Function Type COMMENTAP3 GND - Ground AP5 GND - Ground AP7 GND - Ground AP9 GND - Ground AP11 GND - Ground AP13 GND - Ground AP15 GND - Ground AR2 GND - Ground AR4 GND - Ground AR6 GND - Ground AR8 GND - Ground AR10 GND - Ground AR12 GND - Ground AR14 GND - Ground AR16 GND - Ground AS5 GND - Ground AS7 GND - Ground AS9 GND - Ground AS11 GND - Ground AS13 GND - Ground AS15 GND - Ground AT4 GND - Ground AT6 GND - Ground AT8 GND - Ground AT10 GND - Ground AT12 GND - Ground AT14 GND - Ground AT16 GND - Ground AU1 GND - Ground AU5 GND - Ground AU7 GND - Ground AU11 GND - Ground AU15 GND - Ground Reserved C12 Reserved - Reserved A14 Reserved - Reserved A16 Reserved - Reserved M17 Reserved - Reserved AN6 Reserved - Reserved V2 Reserved - Reserved C14 Reserved - Reserved
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 21 of 76 PAD Signal I/O Function Type COMMENTD13 Reserved - Reserved C16 Reserved - Reserved D17 Reserved - Reserved E16 Reserved - Reserved C18 Reserved - Reserved D15 Reserved - Reserved F15 Reserved - Reserved E4 Reserved - Reserved E8 Reserved - Reserved F3 Reserved - Reserved F5 Reserved - Reserved G2 Reserved - Reserved H1 Reserved - Reserved H3 Reserved - Reserved H17 Reserved - Reserved J2 Reserved - Reserved J18 Reserved - Reserved K1 Reserved - Reserved K3 Reserved - Reserved K17 Reserved - Reserved K19 Reserved - Reserved L2 Reserved - Reserved L18 Reserved - Reserved M3 Reserved - Reserved M19 Reserved - Reserved N18 Reserved - Reserved P19 Reserved - Reserved S3 Reserved - Reserved S17 Reserved - Reserved U3 Reserved - Reserved U17 Reserved - Reserved W3 Reserved - Reserved W17 Reserved - Reserved Y3 Reserved - Reserved Y17 Reserved - Reserved AB3 Reserved - Reserved AB17 Reserved - Reserved AD3 Reserved - Reserved AD17 Reserved - Reserved AF3 Reserved - Reserved AF17 Reseved - Reserved
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 22 of 76 PAD Signal I/O Function Type COMMENTAH3 Reserved - Reserved AH17 Reserved - Reserved AK3 Reserved - Reserved AL2 Reserved - Reserved AM1 Reserved - Reserved AM3 Reserved - Reserved AN2 Reserved - Reserved AN4 Reserved - Reserved AN8 Reserved - Reserved AN14 Reserved - Reserved AS3 Reserved - Reserved AT2 Reserved - Reserved B19 Reserved - Reserved AU13 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 LE920’s 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 isn’t used, all UART signals may be left disconnected NOTE: RESERVED pins must not be connectedNOTE: If not used, almost all pins must be left disconnected. The only exceptions are the following: PAD Signal AP17,AP19,AR18,AS17,AS19,AT18,AU17,AU19 VBATT & VBATT_PA 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, GND
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 23 of 76 AU11,AU15 AS1 ON/OFF*
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 24 of 76 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 25 of 76 4. Hardware Commands 4.1. 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 26 of 76 NOTE: 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):
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 27 of 76 4.3. Turning OFF the LE920 Turning off the device can be done in three ways: x by Software command x by Hardware shutdown x by Hardware Unconditional Restart x 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 28 of 76 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 29 of 76 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 30 of 76 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: 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 RESET# Unconditional Restart impulse GND
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 31 of 76 For 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): 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 SHDN_N Unconditional Shutdown impulse GND
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 32 of 76 4.4. Summary of Turning ON and OFF the module Below chart describes the overall sequences for Turning ON and OFF. NOTE: 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
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 33 of 76 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 3.8V Max Supply Voltage 4.2V Supply Voltage Range 3.3V– 4.2V LE920 current consumption Mode Average(mA) Mode Description SWITCHED OFF Module supplied but switched Off Switched Off 40 uA IDLE mode Standby mode; no call in progress AT+CFUN=1 WCDMA 16 Normal mode; full functionality of the module GSM 16 LTE 16 AT+CFUN=4 10 Disabled TX and RX; modules is not registered on the network AT+CFUN=5 WCDMA 1.7 DRx9 GSM 1.9Operative mode (LTE) LTE (0dBm) 203 LTE data call channel BW 5MHz,RB=1, TX = 0dBm) LTE (22dBm) 540 LTE data call (channel BW 5MHz,RB=1, TX = 22dBm) Operative mode (WCDMA)WCDMA Voice 185 WCDMA voice call (TX = 10dBm) WCDMA HSDPA (0dBm) 100 WCDMA data call (RMC, TX = 0dBm) WCDMA HSDPA (22dBm) 390 WCDMA data call (RMC, TX = 22dBm) Operative mode (GSM) GSM TX and RX mode GSM900 PL5 290 GSM Voice Call DCS1800 PL0 170 GPRS 4TX + 1RX GSM900 PL5 410 GPRS Sending data mode DCS1800 PL0 320 EDGE 4TX + 1RX
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 34 of 76 GSM900 PL5 255 EDGE Sending data modeDCS1800 PL0 240 * 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 35 of 76 5.2. General Design Rules The principal guidelines for the Power Supply Design embrace three different design steps: x the electrical design x the thermal design x the PCB layout 5.2.1. 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: x +5V input (typically PC internal regulator output) x +12V input (typically automotive) x battery 5.2.1.1. + 5V Input Source Power Supply Design Guidelines x 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. x When using a linear regulator, a proper heat sink must be provided in order to dissipate the power generated. x A Bypass low ESR capacitor of adequate capacity must be provided in order to cut the current absorption peaks close to LE920usually suited. x Make sure the low ESR capacitor on the power supply output (usually a tantalum one) is rated at least 10V. x A protection diode must be inserted close to the power input, in order to save LE920 from power polarity inversion.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 36 of 76 An example of linear regulator with 5V input is: 5.2.1.2. + 12V Input Source Power Supply Design Guidelines x 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. x 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. x 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. x 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. x A Bypass low ESR capacitor of adequate capacity must be provided in order to s usually suited for this. x Make sure the low ESR capacitor on the power supply output (usually a tantalum one) is rated at least 10V. x For Car applications a spike protection diode must be inserted close to the power input, in order to clean the supply from spikes. x 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 37 of 76 An example of switching regulator with 12V input is in the below schematic (it is split in 2 parts): Switching regulator
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 38 of 76 5.2.1.3. Battery Source Power Supply Design Guidelines x 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. x A Bypass low ESR capacitor of adequate capacity must be provided in order to cut the current  x Make sure the low ESR capacitor (usually a tantalum one) is rated at least 10V. x 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. x 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 39 of 76 5.2.2. Thermal Design Guidelines The thermal design for the power supply heat sink must be done with the following specifications: x Average current consumption during HSPA transmission @PWR level max in LE920: 640mA (TBD) x Average current consumption during class12 GPRS transmission @PWR level max: 680mA (TBD) x 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 40 of 76 The 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 don’t 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. x 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. x The protection diode must be placed close to the input connector where the power source is drained. x 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. x 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. x 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). x The use of a good common ground plane is suggested. x 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 41 of 76 x The power supply input cables must be kept separately from noise sensitive lines such as microphone/earphone cables.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 42 of 76 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 product’s 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:When using the Telit LE920, since there’s 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: GSM / WCDMA/ LTE Antenna Requirements Frequency range Depending by frequency band(s) provided by the network operator, the customer must use the most suitable antenna for that/those band(s) Bandwidth LE920-EU LE920-NAGSM850 : 70 MHz GSM900 : 80 MHz GSM1800(DCS) : 170 MHz GSM1900(PCS) : 140 MHz WCDMA band I(2100) : 250 MHz WCDMA band III(1800) : 170 MHz WCDMA band VIII(900) : 80 MHz LTE Band I(2100) : 250 MHz LTE band III(1800) : 170 MHz LTE Band VII(2600) : 190 MHz LTE Band VIII(900) : 80 MHz LTE Band XX(800) : 71 MHz GSM850 : 70 MHz GSM900 : 80 MHz GSM1800(DCS) : 170 MHz GSM1900(PCS) : 140 MHz WCDMA band I(2100) : 250 MHz WCDMA band II(1900) : 140 MHz WCDMA band IV(1700) : 445 MHz WCDMA band V(850) : 70 MHz WDCMA band VI(800): 70MHz LTE Band I(2100) : 250 MHz LTE Band II(1900) : 140 MHz LTE Band IV(1700) : 445 MHz LTE Band V (850) : 70 MHz LTE Band XVII(700) : 42 MHz Gain Gain < 3dBi Impedance 50 Ohm Input power > 33dBm(2 W) peak power in GSM > 24dBm Average power in WCDMA & LTE VSWR absolute max <= 10:1 VSWR recommended <= 2:1
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 43 of 76 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 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 – PCB line Guidelines x Make sure that the transmission line’s characteristic impedance is 50ohm. x Keep line on the PCB as short as possible since the antenna line loss shall be less than around 0.3dB. x Line geometry should have uniform characteristics, constant cross section, avoid meanders and abrupt curves. x Any kind of suitable geometry/structure can be used for implementing the printed transmission line afferent the antenna. x 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. x 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. x 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. x Avoid crossing any un-shielded transmission line footprint with other tracks on different layers. x 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. x Place EM noisy devices as far as possible from LE920 antenna line. x Keep the antenna line far away from the LE920 power supply lines. x 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. x 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 44 of 76 6.3. GSM/WCDMA/LTE Antenna – Installation Guidelines x Install the antenna in a place covered by the GSM/WCDMA signal. x 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; x Antenna must not be installed inside metal cases; x Antenna must be installed also according Antenna manufacturer instructions. 6.4. 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 Depending by frequency band(s) provided by the network operator, the customer shall use the most suitable antenna for that/those band(s) Bandwidth LE920-EU LE920-NA WCDMA band I(2100) : 250 MHz WCDMA band III(1800) : 170 MHz WCDMA band VIII(900) : 80 MHz LTE Band I(2100) : 250 MHz LTE band III(1800) : 170 MHz LTE Band VII(2600) : 190 MHz LTE Band VIII(900) : 80 MHz LTE Band XX(800) : 71 MHz WCDMA band I(2100) : 250 MHz WCDMA band II(1900) : 140 MHz WCDMA band IV(AWS) : 445 MHz WCDMA band IV(850) : 445 MHz WCDMA band V(850) : 70 MHzWDCMA band VI(800): 55MHzLTE Band I(2100) : 250 MHz LTE Band II(1900) : 140 MHz LTE Band IV(1700) : 445 MHz LTE Band V (850) : 70 MHz Band XVII(700) : 42 MHz Impedance  VSWR recommended  When using the Telit LE920, since there’s 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 45 of 76 The 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: x An external passive antenna (GPS only) x 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 – 1576.42MHz) = 1.4dB (Max) z Insertion Loss (1565.42 – 1585.42MHz) = 1.4dB (Max) z Insertion Loss (1597.5515 – 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 46 of 76 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 there’s 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 x Ensure that the antenna line impedance is 50ohm. x Keep line on the PCB as short as possible to reduce the loss. x Antenna line must have uniform characteristics, constant cross section, avoid meanders and abrupt curves. x Keep one layer of the PCB used only for the Ground plane; if possible. x Surround (on the sides, over and under) the antenna line on PCB with Ground. Avoid
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 47 of 76 having other signal tracks directly facing the antenna line track. x 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. x Place EM noisy devices as far as possible from LE920 antenna line. x Keep the antenna line far away from the LE920 power supply lines. x 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.x 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. 6.5.5. GPS/GNSS Antenna – Installation Guidelines x 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) x The Antenna must not be co-located or operating in conjunction with any other antenna or transmitter. x Antenna shall not be installed inside metal cases. x Antenna shall be installed also according antenna manufacture instructions.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 48 of 76 7. Logic Level SpecificationsWhere 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 LE920’s digital logic signal directly to OEM’s 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 Parameter LE920 Min Max Input level on any digital pin when on -0.3V +2.16V Input voltage on analog pins when on -0.3V +2.16 V Operating Range - Interface levels (1.8V CMOS) Level LE920 Min Max Input high level 1.5V 2.1V Input low level -0.3V 0.5V Output high level 1.35V 1.8V Output low level 0V 0.45V
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 49 of 76 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: Signal LE920 Pad No. Usage USB_VBUS A18 Power sense for the internal USB transceiver . USB_D- F19 Minus (-) line of the differential, bi-directional USB signal to/from the peripheral device USB D+ D19 Plus (+) line of the differential, bi-directional USB signal to/from the peripheral device
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 50 of 76 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: x MODEM SERIAL PORT 1(Main) x MODEM SERIAL PORT 2 (Auxiliary) -TBD Several configurations can be designed for the serial port on the OEM hardware. The most common are: x RS232 PC com port; x Microcontroller UART @ 1.8V (Universal Asynchronous Receive Transmit) ; x 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 Parameter LE920 Min Max Input level on any digital pin when on -0.3V +2.16 V Input voltage on analog pins when on -0.3V +2.16 V Operating Range - Interface levels Level LE920 Min Max Input high level 1.5V 2.1V Input low level -0.3V 0.5V Output high level 1.35V 1.8V Output low level 0V 0.45V
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 51 of 76 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 Signal LE920 Pad Number Name Usage1 DCD - dcd_uart AE18 Data Carrier Detect Output from the LE920 that indicates the carrier presence 2 RXD - Tx_uart AF19 Transmit line *see Note Output transmit line of the LE920 UART 3 TXD - Rx_uart AH19 Receive line *see Note Input receive of the LE920 UART 4 DTR - dtr_uart AC18 Data Terminal Ready Input to the LE920 that controls the DTE READY condition 5 GND A6, A12, B13, B15…. Ground ground 6 DSR - dsr_uart AG18 Data Set Ready Output from the LE920 that indicates the module is ready 7 RTS -rts_uart AA18 Request to Send Input to the LE920 that controls the Hardware flow control 8 CTS - cts_uart AK19 Clear to Send Output from the LE920 that controls the Hardware flow control 9 RI - ri_uart AJ18 Ring Indicator 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 52 of 76 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 COMMENT AB19 TXD_AUX O Auxiliary UART (TX Data to DTE) 1.8V AD19 RXD_AUX I Auxiliary UART (RX Data to DTE) 1.8V 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: x Invert the electrical signal in both directions; x 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: x 5 drivers x 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 53 of 76 An 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
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 54 of 76 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 Type COMMENT D11 DVI_WA0 I/O Digital Audio Interface (WA0) B-PD 1.8V PCM_SYNC C8 DVI_RX I Digital Audio Interface (RX) B-PD 1.8V PCM_DIN D9 DVI_TX O Digital Audio Interface (TX) B-PD 1.8V PCM_DOUT C10 DVI_CLK I/O Digital Audio Interface (CLK) B-PD 1.8V PCM_CLK LE920 DVI supports PCM master 2048khz short frame
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 55 of 76
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 56 of 76 11. General Purpose I/O The general-purpose I/O pads can be configured to act in three different ways: x input x output x 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 Type Drive Strength F9 GPIO_01 I/O Configurable GPIO BH-PD(*) 1.8V 2 mA E10 GPIO_02 I/O Configurable GPIO BH-PD(*) 1.8V 2 mA F11 GPIO_03 I/O Configurable GPIO BH-PD(*) 1.8V 2 mA E12 GPIO_04 I/O Configurable GPIO BH-PD(*) 1.8V 2 mA F13 GPIO_05 I/O Configurable GPIO BH-PD(*) 1.8V 2 mA E14 GPIO_06 I/O Configurable GPIO BH-PD(*) 1.8V 2 mA R18 GPIO_07 I/O Configurable GPIO BH-PD(*) 1.8V 2 mA S19 GPIO_08 I/O Configurable GPIO BH-PD(*) 1.8V 2 mA U19 GPIO_09 I/O Configurable GPIO BH-PD(*) 1.8V 2 mA W19 GPIO_10 I/O Configurable GPIO BH-PD(*) 1.8V 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 57 of 76 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 Parameter LE920 Min Max Input level on any digital pin when on -0.3V +2.16 V Input voltage on analog pins when on -0.3V +2.16 V Operating Range - Interface levels (1.8V CMOS) Level LE920 Min MaxInput high level 1.5V 2.1V Input low level -0.3V 0.5V Output high level 1.35V 1.8V Output low level 0V 0.45V 11.2. Using a GPIO Pad as InputThe 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 -up resistor to 1.8V.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 58 of 76 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 59 of 76 11.4. Using the Temperature Monitor Function11.4.1. 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 Device Status Permanently off Device off Fast blinking (Period 1s, Ton 0,5s) Net search / Not registered / turning off Slow blinking (Period 3s, Ton 0,3s) Registered full service Permanently on a call is active
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 60 of 76 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 – VAUX power supply Min Typical Max Output voltage 1.75V 1.80V 1.85V Output current 100mA Output bypass capacitor (Inside the module) 1
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 61 of 76 12. ADC section 12.1. ADC Converter 12.1.1. 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. Min Max Units Input Voltage range 0 1.7 Volt AD conversion - 8 bits Resolution - < 6.6 mV The LE920 module provides 3 Analog to Digital Converters. 12.1.2. Using ADC ConverterAn 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 62 of 76 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
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 63 of 76 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 64 of 76 13.4. Stencil Stencil’s apertures layout can be the same as the recommended footprint (1:1). A suggested thickness of stencil foil is greater than 120 µm. 13.5. PCB Pad Design Non solder mask defined (NSMD) type is recommended for the solder pads on the PCB. PCBPCBSolder maskCopper padSolder Mask DefinedCopper padNon Solder Mask Defined 13.6. Recommendations for PCB Pad Dimensions (mm)
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 65 of 76 It 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 Layer thickness (um) Properties Electro-less Ni / Immersion Au 3 –7 / 0.05 – 0.15 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 66 of 76 13.7. Solder PasteSolder Paste Lead free Sn/Ag/Cu We recommend using only “no clean” solder paste in order to avoid the cleaning of the modules after assembly. 13.7.1. Solder Reflow Recommended solder reflow profile:
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 67 of 76 Profile Feature Pb-Free Assembly Average ramp-up rate (TL to TP) 3°C/second max Preheat– Temperature Min (Tsmin) – Temperature Max (Tsmax) – Time (min to max) (ts) 150°C 200°C 60-180 seconds Tsmax to TL – Ramp-up Rate 3°C/second max Time maintained above: – Temperature (TL) – Time (tL) 217°C 60-150 seconds Peak Temperature (Tp) 245 +0/-5°C Time within 5°C of actual Peak Temperature (tp) 10-30 seconds Ramp-down Rate 6°C/second max. Time 25°C to Peak Temperature 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 68 of 76 14. Application guide 14.1. Debug of the LE920 in productionTo 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: x TXD x RXD x ON/OFF x RESET x GND x VBATT x TX_TRACE x RX_TRACE x PWRMON x USB_VBUS x USB_D+ x USB_D-
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 69 of 76 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: z 100uF for Vbatt z 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: z Telit_SIM_interface_and ESD_protection_Application_note_r1
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 70 of 76 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 I/O Function Contact Air Power Supply AP17,AP19,AR18,AS17,AS19,AT18,AU17,AU19 VBATT_PA And VBATT - Main power supply ± 8KV ± 15KV SIM Card Interface A8 SIMVCC - External SIM signal – Power supply for the SIM ± 8KV ± 15KV B11 SIMRST O External SIM signal – Reset ± 8KV ± 15KV B9 SIMIO I/O External SIM signal - Data I/O ± 8KV ± 15KV A10 SIMCLK O External SIM signal – Clock ± 8KV ± 15KV Miscellaneous Functions A18 USB_VBUS AI Power sense for the internal USB transceiver ± 8KV ± 15KV P17 VAUX - Power output for external accessories ± 8KV ± 15KV AS1 ON/OFF I Input command for switching power ON or OFF (toggle command). ± 8KV ± 15KV AP1 RESET I Reset input ± 8KV ± 15KV F17 VRTC AO Power supply for RTC block ± 8KV ± 15KV Antenna AD1,AU9,S1 Antenna Pad AI Antenna pad for Rosenberger connector ± 8KV ± 15KV All other pins have the following characteristics: HBM JESD22-A114-B ± 2000 V CDM JESD22-C101-C ± 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.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 71 of 76 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 Telit’s 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 it’s mounted. Users who use USB interface only to communicate LE920- Must arrange UART port in a host system for debugging or upgrading LE920 when it’s mounted. Users who use UART interface only to communicate LE920 - Must arrange USB port in a host system for debugging or upgrading LE920 when it’s mounted.
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 72 of 76 15. Packing system The Telit LE920 is packaged on trays. Each tray contains 20 pieces as shown in the following picture:
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 73 of 76 15.1. Tray Drawing
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 74 of 76 WARNIG: These trays can withstand a maximum temperature of 65͠. 15.2. Moisture Sensibility The LE920 is a Moisture Sensitive Device level 3, in accordance with standard IPC/JEDEC J-STD-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).
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 75 of 76 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: x Where it can interfere with other electronic devices in environments such as hospitals, airports, aircrafts, etc. x 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
LLE920 Hardware User Guide1vv0301026 Rev.0 - draft4 – 2013-05-Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved. Page 76 of 76 17. Document History Revision Date Changes 0-draft1 2012-10-03 First issue 0-draft2 2012-12-11 - Remove SIM2 interface - Remove external GPS LNA support0-draft3 2013-03-12 Updated pin-out 0-draft4 2013-05-21 - 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. “Contains FCC ID：RI7LE920NA “Contains IC：5131A-LE920NA Label：

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