User's Manual

ManualsBrandsTelit Communications ManualsElectronicsLE920-NA LTE Module

LE920

Hardware User Guide

1vv0301026 Rev.9 - 2016-03-29

Summary of content (88 pages)

PAGE 1
LE920 Hardware User Guide 1vv0301026 Rev.
PAGE 2
LE920 Hardware User Guide 1vv0301026 Rev.8 2015-01-03 APPLICABILITY TABLE PRODUCT LE920-EUG (cs1550f-B) LE920-NAG (cs1550f-A) LE920-EU (cs1647c) LE920-NA (cs1701) LE920-CN (cs1648D) LE920-NA AUTO S (cs1717) APPLICABILITY TABLE 1 Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
PAGE 3
LE920 Hardware User Guide 1vv0301026 Rev.8 2015-01-03 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.
PAGE 4
LE920 Hardware User Guide 1vv0301026 Rev.8 2015-01-03 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.
PAGE 5
LE920 Hardware User Guide 1vv0301026 Rev.8 2015-01-03 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 .......
PAGE 6
LE920 Hardware User Guide 1vv0301026 Rev.8 2015-01-03 4.2. Initialization and Activation state ...................... 29 4.3. Turning OFF the LE920 .................................... 30 4.3.1. 4.3.2. 4.3.3. 4.3.4. 4.4. 5. Shutdown Hardware Hardware Hardware by Software Command ............................... Shutdown .......................................... Unconditional Restart (RESET) ..................... Unconditional Shutdown ............................
PAGE 7
LE920 Hardware User Guide 1vv0301026 Rev.8 2015-01-03 10. Peripheral Ports ............................................ 57 10.1. SPI – Serial Peripheral Interface ...................... 57 10.2. I2C - Inter-integrated circuit ......................... 58 10.3. SDIO – Secure Digital I/O .............................. 58 10.4. Wi-Fi (SDIO) control Interface ......................... 60 11. Audio Section Overview ...................................... 61 11.1. Analog Audio .........................
PAGE 8
LE920 Hardware User Guide 1vv0301026 Rev.8 2015-01-03 15.1. Debug of the LE920 in production ....................... 75 15.2. Bypass capacitor on Power supplies ..................... 76 15.3. SIM interface .......................................... 77 15.3.1. 15.3.2. SIM schematic example .................................... 77 eSIM interface guidelines ................................ 78 15.4. EMC recommendations .................................... 80 15.5. Download and Debug Port ..........
PAGE 9
LE920 Hardware User Guide 1vv0301026 Rev.8 1. Introduction 1.1. Scope 2015-01-03 The aim of this document is to present possible and recommended hardware solutions useful for developing a product with the Telit LE920 module. All the features and solutions detailed are applicable to all LE920, where “LE920” refers to the modules listed in the applicability table. If a specific feature is applicable to a specific product, it will be clearly highlighted.
PAGE 10
LE920 Hardware User Guide 1vv0301026 Rev.8 1.4. 2015-01-03 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.
PAGE 11
LE920 Hardware User Guide 1vv0301026 Rev.8 1.5. 2015-01-03 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.
PAGE 12
LE920 Hardware User Guide 1vv0301026 Rev.8 2. 2.1. 2015-01-03 General Product Description Overview The aim of this document is to present possible and recommended hardware solutions useful for developing a product with the Telit LE920 module. In this document all the basic functions of a wireless module will be taken into account; for each one of them a valid hardware solution will be suggested and usually incorrect solutions and common errors to be avoided will be highlighted.
PAGE 13
LE920 Hardware User Guide 1vv0301026 Rev.8 2.2. 2015-01-03 LE920 Mechanical Dimensions The Telit LE920 module overall dimensions are: 2.3. • Length: 34 mm , +/- 0.15 mm Tolerance • Width: 40 mm , +/- 0.15 mm Tolerance • Thickness: 2.9 mm , +/- 0.13 mm Tolerance Weight The module weight of LE920 is about 9.0 gram. Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
PAGE 14
LE920 Hardware User Guide 1vv0301026 Rev.8 2.4. 2015-01-03 Environmental requirements 2.4.1. Temperature range Operating Temperature Range –40°C ~ +85°C Storage and non-operating Temperature Range –40°C ~ +85°C 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 2011/65/EU).
PAGE 15
LE920 Hardware User Guide 1vv0301026 Rev.8 2.5. 2015-01-03 Operating Frequency The operating frequencies in GSM850, EGSM900, DCS1800, PCS1900, WCDMA & LTE modes are conformed to the 3GPP specifications. 2.5.1. LE920-EUG(cs1550f-B), LE920-EU (cs1647c) Mode GSM850 DCS1800 PCS1900 Freq. TX (MHz) 824 ~ 849 890 ~ 915 880 ~ 890 1710 ~ 1785 1850 ~ 1910 Freq.
PAGE 16
LE920 Hardware User Guide 1vv0301026 Rev.
PAGE 17
LE920 Hardware User Guide 1vv0301026 Rev.8 LTE1700 – B4 1710~ 1755 2110 ~ 2155 LTE850 – B5 824 ~ 849 869 ~ 894 LTE2600 – B7 2500 ~ 2570 2620 ~ 2690 LTE700 – B17 704 ~ 716 734 ~ 746 2.5.4. Tx: 19950 ~ 20399 Rx: 1950 ~ 2399 Tx: 20400 ~ 20649 Rx: 2400 ~ 2649 Tx: 20750 ~ 21449 Rx: 2750 ~ 3449 Tx: 23730 ~ 23849 Rx: 5730 ~ 5849 2015-01-03 400MHz 45MHz 120MHz 30MHz LE920-CN (cs1648D) Mode DCS1800 Freq. TX (MHz) 890 ~ 915 880 ~ 890 1710 ~ 1785 Freq.
PAGE 18
LE920 Hardware User Guide 1vv0301026 Rev.8 2.6. 2015-01-03 Sensitivity LE920 maximum sensitivity levels are as follow:  -113 dBm @ 2G  -112 dBm @ 3G  -111 dBm @ TD-SCDMA (BW=1.6MHz)  -102 dBm @ 4G FDD (BW=5MHz)  -101 dBm @ 4G TDD (BW=5MHz) 2.7. Conformity assessment issues 2.7.1. FCC/IC Regulatory notices 2.7.1.1. Modification statement Telit has not approved any changes or modifications to this device by the user.
PAGE 19
LE920 Hardware User Guide 1vv0301026 Rev.8 1700 MHz 1900 MHz 2600 MHz 2015-01-03 5,00 dBi 8,01 dBi 8,01 dBi This transmitter must not be co-located or operating in conjunction with any other antenna or transmitter. Cet appareil est conforme aux limites d'exposition aux rayonnements de la IC pour un environnement non contrôlé. L'antenne doit être installé de façon à garder une distance minimale de 20 centimètres entre la source de rayonnements et votre corps.
PAGE 20
LE920 Hardware User Guide 1vv0301026 Rev.8 2015-01-03 Contains FCC ID: RI7LE920NA1 Contains IC: 5131A-LE920NA1 L'appareil hôte doit être étiqueté comme il faut pour permettre l'identification des modules qui s'y trouvent. L'étiquette de certification du module donné doit être posée sur l'appareil hôte à un endroit bien en vue en tout temps.
PAGE 21
LE920 Hardware User Guide 1vv0301026 Rev.8 3. LE920 Module Connections 3.1. PIN-OUT PAD Signal I/O Function USB HS 2.0 Communication Port I/O USB differential Data(+) D19 USB_D+ USB_DI/O USB differential Data(-) F19 A18 USB_VBUS AI Power sense for the internal USB transceiver Asynchronous UART – Prog.
PAGE 22
LE920 Hardware User Guide 1vv0301026 Rev.
PAGE 23
LE920 Hardware User Guide 1vv0301026 Rev.8 PAD Signal AN12 SHDN_N P17 F17 2015-01-03 I/O Function Type I Unconditional Shut down Input Supply Output for External Accessories / Power ON VAUX/PWRMON O 1.
PAGE 24
LE920 Hardware User Guide 1vv0301026 Rev.
PAGE 25
LE920 Hardware User Guide 1vv0301026 Rev.
PAGE 26
LE920 Hardware User Guide 1vv0301026 Rev.
PAGE 27
LE920 Hardware User Guide 1vv0301026 Rev.
PAGE 29
LE920 Hardware User Guide 1vv0301026 Rev.8 4. Hardware Commands 4.1. Turning ON the LE920 2015-01-03 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.
PAGE 30
LE920 Hardware User Guide 1vv0301026 Rev.8 2015-01-03 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 cause latch-up problems on the LE920 power regulator and improper powering on/off of the module. The line ON# must be connected only in an open collector configuration.
PAGE 31
LE920 Hardware User Guide 1vv0301026 Rev.8 4.3.1. 2015-01-03 Shutdown by Software Command LE920 can be shut down by a software command. When a shutdown command is sent, LE920 goes into the finalization state and finally will shut down PWRMON at the end of this state. The duration of the finalization state can differ according to the situation in which the LE920 is, so a value cannot be defined.
PAGE 32
LE920 Hardware User Guide 1vv0301026 Rev.8 4.3.2. 2015-01-03 Hardware Shutdown To turn OFF LE920 the pad ON/OFF# must be tied low for at least 2 seconds and then released. The same circuitry and timing for the power on must be used. When the hold time of ON/OFF# is above 2.5 seconds, LE920 goes into the finalization state and finally will shut down PWRMON at the end of this state.
PAGE 33
LE920 Hardware User Guide 1vv0301026 Rev.8 4.3.3. 2015-01-03 Hardware Unconditional Restart (RESET) To unconditionally restart LE920, the pad RESET# must be tied low for period between 500 2000 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 cause latch-up problems on the LE920 power regulator and improper functioning of the module.
PAGE 34
LE920 Hardware User Guide 1vv0301026 Rev.8 4.3.4. 2015-01-03 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: NOTE: Do not use any pull up resistor on the SHDN_N line or any totem pole digital output. Using pull up resistor may cause latch-up problems on the LE920 power regulator and improper functioning of the module.
PAGE 35
LE920 Hardware User Guide 1vv0301026 Rev.8 4.4. 2015-01-03 Summary of Turning ON and OFF the module The chart below describes the overall sequences for Turning ON and OFF. Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
PAGE 36
LE920 Hardware User Guide 1vv0301026 Rev.8 5. 2015-01-03 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 overall product performance. Reading carefully the requirements and the guidelines that follow will ensure a good and proper design. 5.1.
PAGE 37
LE920 Hardware User Guide 1vv0301026 Rev.8 LTE (0dBm) LTE (22dBm) WCDMA Voice WCDMA HSDPA (0dBm) WCDMA HSDPA (22dBm) 2015-01-03 2.5 Paging cycle #128 frames (1.28 sec DRx cycle) 1.9 Paging cycle #256 frames (2.
PAGE 38
LE920 Hardware User Guide 1vv0301026 Rev.8 5.2. 2015-01-03 General Design Rules The principal guidelines for the Power Supply Design embrace three different design steps: 5.2.1.  the electrical design  the thermal design  the PCB layout Electrical Design Guidelines The electrical design of the power supply depends strongly on the power source where this power is drained. We will distinguish them into three categories: 5.2.1.1.
PAGE 39
LE920 Hardware User Guide 1vv0301026 Rev.8 2015-01-03 An example of linear regulator with 5V input is: 5.2.1.2. + 12V Input Source Power Supply Design Guidelines  The desired output for the power supply is 3.8V, hence due to the big difference between the input source and the desired output, a linear regulator is unsuitable 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.
PAGE 40
LE920 Hardware User Guide 1vv0301026 Rev.8 2015-01-03 An example of switching regulator with 12V input is in the below schematic (it is split in 2 parts): Switching regulator Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
PAGE 41
LE920 Hardware User Guide 1vv0301026 Rev.8 5.2.1.3. 2015-01-03 Battery Source Power Supply Design Guidelines  The desired nominal output for the power supply is 3.8V and the maximum allowed voltage is 4.2V, hence a single 3.7V Li-Ion cell battery type is suited for supplying the power to the Telit LE920 module. 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.
PAGE 42
LE920 Hardware User Guide 1vv0301026 Rev.8 5.2.2.
PAGE 43
LE920 Hardware User Guide 1vv0301026 Rev.8 2015-01-03 Even though peak current consumption in GSM mode is higher than in WCDMA, consideration for the heat sink is more important in the case of WCDMA. As mentioned before, a GSM signal is bursty, thus, the temperature drift is more insensitive than WCDMA. Consequently, if you successfully manage heat dissipation in WCDMA mode, you don’t need to think more about GSM mode. 5.2.3.
PAGE 44
LE920 Hardware User Guide 1vv0301026 Rev.8  2015-01-03 The power supply input cables must be kept separate from noise sensitive lines such as microphone/earphone cables. Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
PAGE 45
LE920 Hardware User Guide 1vv0301026 Rev.8 6. 2015-01-03 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 performance. Read carefully and follow the requirements and the guidelines for a good and proper design. 6.1.
PAGE 46
LE920 Hardware User Guide 1vv0301026 Rev.8 Characteristic Impedance 2015-01-03 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 approval requirements: This device is to be used only for mobile and fixed application.
PAGE 47
LE920 Hardware User Guide 1vv0301026 Rev.8 6.3. 6.4. 2015-01-03 GSM/WCDMA/LTE Antenna – Installation Guidelines  Install the antenna in a location with access to the network radio signal.
PAGE 48
LE920 Hardware User Guide 1vv0301026 Rev.8 2015-01-03 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. The second Rx antenna should not be located in the close vicinity of the main antenna.
PAGE 49
LE920 Hardware User Guide 1vv0301026 Rev.8 2015-01-03 NOTE: It is recommended to add a DC block to the customer’s GPS application in order to prevent damage to the LE920 due to unwanted DC voltage 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.
PAGE 50
LE920 Hardware User Guide 1vv0301026 Rev.8 2015-01-03 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           6.5.5. Ensure that the antenna line impedance is 50ohm. Keep the line on the PCB as short as possible to reduce the loss.
PAGE 51
LE920 Hardware User Guide 1vv0301026 Rev.8 7. 2015-01-03 Logic Level Specifications Where not specifically stated, all the interface circuits work at 1.8V CMOS logic levels. The following table shows the logic level specifications used in the Telit LE920 interface circuits: NOTE: Do not connect LE920’s digital logic signal directly to OEM’s digital logic signal with a level higher than 2.7V for 1.8V CMOS signals. For 1.
PAGE 52
LE920 Hardware User Guide 1vv0301026 Rev.8 8. 2015-01-03 USB Port The LE920 module includes a Universal Serial Bus (USB) transceiver, which operates at USB high-speed (480Mbits/sec). It can also work with USB full-speed (12Mbits/sec) hosts It is compliant with the USB 2.0 specification and can be used control and data transfers as well as for diagnostic monitoring and firmware update. In fact firmware update by the host is only possible via USB and not possible via UART.
PAGE 53
LE920 Hardware User Guide 1vv0301026 Rev.8 9. 2015-01-03 Serial Ports The serial port on the Telit LE920 is typically a secondary interface between the module and OEM hardware. Two serial ports are available on the module:  MODEM SERIAL PORT 1(Main)  MODEM SERIAL PORT 2 (Auxiliary) Several configurations can be designed for the serial port on the OEM hardware. The most common are:  RS232 PC com port;  Microcontroller UART @ 1.
PAGE 54
LE920 Hardware User Guide 1vv0301026 Rev.8 9.1. 2015-01-03 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.
PAGE 55
LE920 Hardware User Guide 1vv0301026 Rev.8 9.2. 2015-01-03 Modem Serial Port 2 Serial port 2 on the LE920 is a +1.8V UART with only the RX and TX signals. The signals of the LE920 serial port are: PAD Signal I/O Function Type AB19 TXD_AUX O Auxiliary UART (TX Data to DTE) 1.8V Auxiliary UART (RX Data to DTE) 1.
PAGE 56
LE920 Hardware User Guide 1vv0301026 Rev.8 2015-01-03 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 the length of the lines on the application must be taken into account to avoid problems in the case of High-speed rates on RS232.
PAGE 57
LE920 Hardware User Guide 1vv0301026 Rev.8 10. 2015-01-03 Peripheral Ports In addition to Telit LE920 serial ports, the LE920 supports the following peripheral ports: 10.1.  SPI – Serial Peripheral Interface  I2C - Inter-integrated circuit  2 x SDIO – Secure Digital I/O SPI – Serial Peripheral Interface The LE920 SPI supports the following:  Master Mode only  1.8V CMOS level  Up to 26MHz clock rate NOTE: SPI is supported only on the Linux side.
PAGE 58
LE920 Hardware User Guide 1vv0301026 Rev.8 10.2. 2015-01-03 I2C - Inter-integrated circuit The LE920 I2C is an alternate function of our GPIO 1-10 pins. Any GPIO can be configured as SCL and SDA Available only from Modem side as SW emulation of I2C on GPIO lines. LE920 supports I2C Master Mode only. NOTE: I2C is supported only on from Modem side as SW emulation of I2C on GPIO lines. Refer to LE920 AT SW manual for command settings 10.3.
PAGE 59
LE920 Hardware User Guide 1vv0301026 Rev.8 2015-01-03 Connection diagram of the SD interface is shown below: Ext, Card supply LE920 SDIO Interface C=100nF GND 10K 10K 10K 10K SW2 10K microSD DATA2 DATA3 CMD VDD CLK VSS DATA0 DATA1 SD/MMC_DATA2 SD/MMC_DATA3 SD/MMC_CMD SW1 SD/MMC_CD GND SD/MMC_CLK SD/MMC_DATA0 SD/MMC_DATA1 GND NOTE: 1. SDIO is supported only on the Linux side. 2. SD/MMC card supply shall be provided by the Host application board.
PAGE 60
LE920 Hardware User Guide 1vv0301026 Rev.8 10.4. 2015-01-03 Wi-Fi (SDIO) control Interface The LE920 has an integrated SW driver for supporting Qualcomm QCA6053 Wi-Fi chipset via a 2nd dedicated SD bus interface. The secondary SD bus interface can be used only with the QCA6053 chipset, and can’t be used as external SD/MMC card connection.
PAGE 61
LE920 Hardware User Guide 1vv0301026 Rev.8 11. 2015-01-03 Audio Section Overview The LE920 module support analog and digital audio interfaces. 11.1. Analog Audio The LE920 module provides single analog audio path transmitting and receiving. Please refer to the xE920_Audio_Settings_Application_Note, 80404NT10095A WARNING: LE920 Analog audio implementation uses an internal CODEC.
PAGE 63
LE920 Hardware User Guide 1vv0301026 Rev.8 12.
PAGE 64
LE920 Hardware User Guide 1vv0301026 Rev.8 12.1. 2015-01-03 Logic Level Specifications Where not specifically stated, all the interface circuits work at 1.8V CMOS logic levels. The following table shows the logic level specifications used in the LE920 interface circuits: For 1,8V signals: Absolute Maximum Ratings -Not Functional LE920 Parameter Min Max Input level on any -0.3V +2.16 V digital pin when on Input voltage on -0.3V +2.16 V analog pins when on Operating Range - Interface levels (1.
PAGE 65
LE920 Hardware User Guide 1vv0301026 Rev.8 12.3. 2015-01-03 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. 12.4. Using the Temperature Monitor Function 12.4.1.
PAGE 66
LE920 Hardware User Guide 1vv0301026 Rev.8 12.5. 2015-01-03 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.
PAGE 67
LE920 Hardware User Guide 1vv0301026 Rev.8 12.6. 2015-01-03 RTC Bypass The VRTC pin brings out the Real Time Clock supply, which is separate from the rest of the digital part, allowing having only the RTC operating when all the other parts of the device are turned off. If maintaining internal RTC block is needed, it recommended to connect a backup capacitor or a coin cell to this pin (valid range from 2.5V to 3.2V), otherwise, it can be left unconnected Operating Modes: 1.
PAGE 68
LE920 Hardware User Guide 1vv0301026 Rev.8 13. ADC section 13.1. ADC Converter 2015-01-03 13.1.1. 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. Input Voltage range AD conversion Resolution Min 0 - Max 1.7 8 < 6.6 Units Volt bits mV The LE920 module provides 3 Analog to Digital Converters. 13.1.2.
PAGE 69
LE920 Hardware User Guide 1vv0301026 Rev.8 2015-01-03 14. Mounting the module on your board 14.1. General The LE920 modules have been designed to be compliant with a standard lead-free SMT process. 14.2. Finishing & Dimensions Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
PAGE 70
LE920 Hardware User Guide 1vv0301026 Rev.8 14.3. 2015-01-03 Recommended foot print for the application 198 pads Top View In order to easily rework the LE920 it is suggested to consider that the application has 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.
PAGE 71
LE920 Hardware User Guide 1vv0301026 Rev.8 14.4. 2015-01-03 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. 14.5. PCB Pad Design Non solder mask defined (NSMD) type is recommended for the solder pads on the PCB. Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
PAGE 72
LE920 Hardware User Guide 1vv0301026 Rev.8 14.6. 2015-01-03 Recommendations for PCB Pad Dimensions (mm) 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 Electro-less Ni / Immersion Au Layer thickness (um) 3 –7 / 0.05 – 0.
PAGE 73
LE920 Hardware User Guide 1vv0301026 Rev.8 14.7. 2015-01-03 Solder Paste Solder 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. 14.7.1. Solder Reflow Recommended solder reflow profile: Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
PAGE 74
LE920 Hardware User Guide 1vv0301026 Rev.
PAGE 75
LE920 Hardware User Guide 1vv0301026 Rev.8 15. Application guide 15.1. Debug of the LE920 in production 2015-01-03 To test and debug the mounting of LE920, we strongly recommend foreseeing 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 by connecting it with an external computer.
PAGE 76
LE920 Hardware User Guide 1vv0301026 Rev.8 15.2. 2015-01-03 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 overshoot and undershoot. This abrupt voltage transition can affect the device causing it to not work or make it malfunction. Bypass capacitors are needed to alleviate this behavior. The behavior can be affected differently according to the various applications.
PAGE 77
LE920 Hardware User Guide 1vv0301026 Rev.8 15.3. 2015-01-03 SIM interface This section deals with the recommended schematics for the design of SIM interfaces on the application boards. 15.3.1. SIM schematic example Figure 1 illustrates in particular how the application side should be designed, and what values the components should have.
PAGE 78
LE920 Hardware User Guide 1vv0301026 Rev.8 2015-01-03 15.3.2. eSIM interface guidelines NOTE: eSIM feature available with LE920-NA AUTO S model only. LE920-NA AUTO S model designed to operate either with internal build-in eSIM, external SIM card or with both options, switching SIM cards using following setups:  For using internal eSIM configuration only, connect E8 pin “ESIM_RST” to B11 “SIMRST1”.
PAGE 79
LE920 Hardware User Guide 1vv0301026 Rev.8 2015-01-03  For external SIM configuration only, leave E8 open (or set to GND) and follow 15.3.1 section guidelines.  For configuration with both internal eSIM and external SIM cards use following approach: 1) Both eSIM and external SIM share the same lines except SIMRST1 and SIMIN1 lines that should be switched between them, either electronically or manually.
PAGE 80
LE920 Hardware User Guide 1vv0301026 Rev.8 15.4. 2015-01-03 EMC recommendations All LE920 signals are provided with some EMC protection. Nevertheless the accepted level differs according to which pin. The characteristics are described in the following Table: Pad Signal I/O Function All Pins All AD1,AU9,S1 Antenna Pads Contact Air ± 4KV ± 8KV ± 8KV ± 15KV Antenna AI Antenna pad Appropriate series resistors must be considered to protect the input lines from overvoltage.
PAGE 81
LE920 Hardware User Guide 1vv0301026 Rev.8 15.5. 2015-01-03 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 software and debug LE920 when LE920 is already mounted on a host system. Users who use both UART and USB interfaces to communicate with LE920 - Must implement a USB download method in a host system for upgrading LE920 when it is mounted.
PAGE 82
LE920 Hardware User Guide 1vv0301026 Rev.8 16. 2015-01-03 Packing system The Telit LE920 is packaged on trays. The tray is JEDEC compliant, injection molded antistatic Modified Polyphenylene ether (MPPO). It has good thermal characteristics and can withstand a the standard baking temperature up to 125°C, thereby avoiding handling the modules if baking is required. The trays are rigid, thus providing more mechanical protection against transport stress.
PAGE 85
LE920 Hardware User Guide 1vv0301026 Rev.8 16.2. 2015-01-03 Moisture Sensitivity The LE920 is a Moisture Sensitive Device level 3, in accordance with standard IPC/JEDEC JSTD-020. Observe all of the requirements for using this kind of components. Calculated shelf life in sealed bag: 4 months at <40°C and <90% relative humidity (RH). Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
PAGE 86
LE920 Hardware User Guide 1vv0301026 Rev.8 17. 2015-01-03 Safety Recommendations READ CAREFULLY Be sure 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 must be avoided in the following areas:  Where it can interfere with other electronic devices in environments such as hospitals, airports, aircrafts, etc.  Where there is risk of explosion such as gasoline stations, oil refineries, etc.
PAGE 87
LE920 Hardware User Guide 1vv0301026 Rev.8 18. 2015-01-03 Document History Revision 0-draft1 0-draft2 Date 2012-10-03 2012-12-11 0-draft3 0-draft4 2013-03-12 2013-05-21 0-draft5 2013-10-08 1 2014-02-04 2 2014-04-02 3 2014-09-26 4 2015-03-19 5 2015-04-27 Changes First issue - Remove SIM2 interface - Remove external GPS LNA support Updated pin-out - Update DVI - Adding Current consumption - Adding SHDN_N section - Update Mechanical drawings - Remove VRTC support - Section 2.
PAGE 88
LE920 Hardware User Guide 1vv0301026 Rev.8 6 7 2015-06-25 2015-09-21 8 2016-02-02 9 2016-03-29 2015-01-03 - Section 3.1 correct pad F19 Function description - APPLICABILITY TABLE 1 – adding LE920-CN, LE920NA AUTO S models. Added cs numbers per model. - Section 1.4 Document Organization links fixed. - Section 2.5 - Added cs numbers per model. - Added section 2.5.4 – LE920-CN model bands. - LE920-NA AUTO S added to section 2.5.3 - Section 2.6 - added sensitivity levels for TD-SCDMA & 4G TDD.