Telit Wireless Solutions LM940 Design Manual
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Telit Wireless Solutions LM940 Design Manual

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LM940
HW Design Guide
1VV0301352 Rev. 18 – 2022-01-04
Telit Technical Documentation

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Summary of Contents for Telit Wireless Solutions LM940

  • Page 1 LM940 HW Design Guide 1VV0301352 Rev. 18 – 2022-01-04 Telit Technical Documentation...

  • Page 2: Applicability Table

    PRODUCTS LM940 1.0 LM940 2.0 Note: The main difference between LM940 HW Versions 1.0 and 2.0 is the pin-out. The two versions are slightly different in terms of POWER ON/OFF control. For more details. refer to the chapter 3. Pins Allocation and 6. Digital Section 1VV0301352 Rev.

  • Page 3: Table Of Contents

    LM940 Hardware Design Guide CONTENTS APPLICABILITY TABLE CONTENTS INTRODUCTION Scope Audience Contact Information, Support Symbol Conventions Related Documents GENERAL PRODUCT DESCRIPTION Overview Product Variants and Frequency Bands 2.2.1. RF Bands per Regional Variant 2.2.1.1. Generic Image Frequency Bands and CA Combinations 2.2.1.2.
  • Page 4 LM940 Hardware Design Guide 3.1.1. LM940 1.0 Pin-Out 3.1.2. LM940 2.0 Pin-Out LM940 Signals That Must Be Connected Pin Layout POWER SUPPLY Power Supply Requirements Power Consumption General Design Rules 4.3.1. Electrical Design Guidelines 4.3.1.1. + 5V Input Source Power Supply – Design Guidelines 4.3.2.
  • Page 5 LM940 Hardware Design Guide 6.3.2.1. Fast Shutdown by AT Command 6.3.2.2. Fast Shutdown by GPIO 6.3.3. Unconditional Shutdown (Support Only on LM940 2.0) Reset 6.4.1. Graceful Reset 6.4.2. Unconditional Hardware Reset Dying Gasp Communication Ports 6.6.1. USB Interface 6.6.2. SIM Interface 6.6.2.1.
  • Page 6 LM940 Hardware Design Guide Finishing and Dimensions Drawing APPLICATION GUIDE Debug of the LM940 Module in Production Bypass Capacitor on Power Supplies EMC Recommendations PACKAGING Tray CONFORMITY ASSESTMENT ISSUES Approval Summary RED Approval 11.2.1. RED Declaration of Conformity FCC Certificates...
  • Page 7 LM940 Hardware Design Guide DOCUMENT HISTORY 1VV0301352 Rev. 18 Page 7 of 75 2022-01-04 Not Subject to NDA...

  • Page 8: Introduction

    This document introduces the Telit LM940 module and presents possible and recommended hardware solutions for developing a product based on the LM940 module. All the features and solutions detailed in this document are applicable to all LM940 variants, where “LM940” refers to the variants listed in the Applicability Table.
  • Page 9 LM940 Hardware Design Guide https://www.telit.com/contact-us For detailed information about where you can buy the Telit modules or for recommendations on accessories and components visit: https://www.telit.com Our aim is to make this guide as helpful as possible. Keep us informed of your comments and suggestions for improvements.

  • Page 10: Symbol Conventions

    • LM940 AT Commands Reference Guide, 80545ST10791A • Generic EVB HW User Guide, 1VV0301249 • LM940 Interface Board HW User Guide, 1VV0301384 • SIM Integration Design Guide Application Note Rev10, 80000NT10001A • Antenna Detection Application Note, 80000NT10002A 1VV0301352 Rev. 18...

  • Page 11: General Product Description

    • LTE / WCDMA networks for data communication • Designed for industrial grade quality In its most basic use case, LM940 can be used as a wireless communication front-end for mobile products, providing mobile communication features to an external host CPU through its rich interfaces.

  • Page 12: At And T Image Frequency Bands And Ca Combinations

    LM940 Hardware Design Guide LTE FDD LTE TDD HSPA+ CA_1A_3A_5A, CA_1A_3A_8A, CA_1A_3A_20A, CA_1A_3A_28A, CA_1A_5A_7A, CA_1A_7A_20A, CA_1A_7A_28A, CA_3A_3A_8A, CA_3A_7A_8A, CA_3A_7A_20A, CA_3A_7A_28A, CA_1A_3C, CA_3A_7B, CA_3A_7C, CA_3C_5A, CA_3C_7A, CA_3C_20A, CA_5A_40C, CA_7B_28A, CA_7C_28A, CA_28A_40C, CA_40D Table 2: Generic Image Frequency Bands 2.2.1.2. AT and T Image Frequency Bands and CA Combinations...

  • Page 13: Target Market

    Refer to Chapter 12. Reference Table of RF Bands Characteristics for details information about frequencies and bands. Target Market LM940 can be used for applications where very high bandwidth, extensive band coverage and multiple network carriers certifications in a single SKU are required, such as: • Industrial equipment •...

  • Page 14: Block Diagram

    (conditions as defined in Section 2.10.1, Temperature Range) Table 6: Functional Features Block Diagram Below figure shows an overview of the internal architecture of the LM940 module. Figure 1: LM940 Block Diagram It includes the following sub-functions: • Application processor, Module subsystem and Location processing with their external interfaces.

  • Page 15: Rx Sensitivity

    LM940 Hardware Design Guide RX Sensitivity Below the 3GPP measurement conditions used to define the RX sensitivity: Technology 3GPP Compliance Throughput >95% 10MHz Dual Receiver 4G LTE BER <0.1% 12.2 Kbps Dual Receiver 3G WCDMA Table 8: Reception Sensitivity Product...

  • Page 16: Mechanical Specifications

    • Length: 50.95 mm, +/- 0.15 mm tolerance • Width: 30.00 mm, +/- 0.15 mm tolerance • Thickness: 2.70 mm, +/- 0.15 mm tolerance 2.9.2. Weight The nominal weight of the LM940 module is gram. 1VV0301352 Rev. 18 Page 16 of 75 2022-01-04...

  • Page 17: Environmental Requirements

    Temperature Range Table 11: Temperature Range 2.10.2. RoHS Compliance As a part of the Telit corporate policy of environmental protection, the LM940 complies with the RoHS (Restriction of Hazardous Substances) directive of the European Union (EU directive 2011/65/EU). 1VV0301352 Rev. 18...

  • Page 18: Pins Allocation

    LM940 Hardware Design Guide 3. PINS ALLOCATION Pin-Out Note: The main difference between LM940 1.0 and LM940 2.0 is the pin-out. Pins highlighted in Blue show that these pins are assigned differently to LM940 1.0 and LM940 2.0. Otherwise, they support same features and functions.
  • Page 19 LM940 Hardware Design Guide Signal Function Type Comment SIMCLK2 Clock output to an external UIM2 card 1.8 / 2.85V SIMRST2 Reset output to an external UIM2 card 1.8 / 2.85V Digital I/O (GPIOs) GPIO_01 General purpose I/O Can be used as 1.8V...
  • Page 20 Ground Ground Reserved Reserved Reserved (NC) Reserved Reserved (NC) Reserved Reserved (NC) Reserved Reserved (NC) Table 12: LM940 1.0 Pin-out Information 3.1.2. LM940 2.0 Pin-Out Signal Function Type Comment USB HS 2.0 Communication Port USB_D+ USB 2.0 Data Plus Analog USB_D- USB 2.0 Data Minus...
  • Page 21 LM940 Hardware Design Guide Signal Function Type Comment USB_SS_TX_M USB 3.0 super-speed transmit – minus Analog USB_SS_RX_P USB 3.0 super-speed receive – plus Analog USB_SS_RX_M USB 3.0 super-speed receive – minus Analog SIM Card Interface 1 SIMVCC1 Supply output for an external UIM1 card 1.8V /...
  • Page 22 LM940 Hardware Design Guide Signal Function Type Comment WAN_LED_N LED control Open drain Miscellaneous Functions VREG_L6_1P8 Reference Voltage 1.8V Power SYSTEM_RESET_N Reset Input 1.8V Power ON Trigger I2C Interface I2C_SCL I2C Clock 1.8V I2C_SDA I2C Data 1.8V Power Supply VBATT...
  • Page 23 Note: Unless otherwise specified, RESERVED pins must be left unconnected (Floating). LM940 Signals That Must Be Connected Below table specifies the LM940 signals that must be connected for debugging purposes even if not used by the end application: Signal Notes...
  • Page 24 LM940 Hardware Design Guide Pin Layout Note: The only difference between LM940 1.0 and LM940 2.0 is the pin-out. Pins highlighted in Blue show that these pins are assigned differently to LM940 1.0 and LM940 2.0. Otherwise, they support same features and functions.
  • Page 25 LM940 Hardware Design Guide Figure 3: LM940 2.0 Pin Layout 1VV0301352 Rev. 18 Page 25 of 75 2022-01-04 Not Subject to NDA...
  • Page 26 Supply voltage range 3.10V – 3.60V Maximum ripple on module input supply 30 mV Table 15: Power Supply Requirements Power Consumption Below table provides typical current consumption values of LM940 for various operation modes. Mode Average [Typ.] Mode Description IDLE Mode...
  • Page 27 • Verify the low ESR capacitor on the power supply output (usually a tantalium one) is rated at least 10V. • A protection diode must be inserted close to the power input to protect the LM940 module from power polarity inversion.
  • Page 28 Therefore, special attention must be paid to dissipate the generated heat. While designing the application board, the designer must make sure that the LM940 module is located on a large ground area of the application board for effective heat dissipation.
  • Page 29 PCB trace from the capacitor to LM940 is wide enough to ensure a low voltage drop connection even during the 2A current peaks.
  • Page 30 Table 17: LM940 VREG_l6_IP8 Signal Internal LDO for GNSS Bias The LDO for GNSS bias is applied inside the LM940 model. The voltage supply come from LM940’s LDO to GNSS active antenna. This table lists the LDO for GNSS bias of LM940.
  • Page 31 LM940 Hardware Design Guide 5. ELECTRICAL SPECIFICATIONS Absolute Maximum Ratings – Not Operational Warning: A deviation from the value ranges listed below may harm the LM940 module. Symbol Parameter Unit Battery supply voltage on VBATT -0.5 pin VBATT Table 19: Battery Supply Voltage on Pin VBATT...
  • Page 32 6. DIGITAL SECTION Logic Levels Unless otherwise specified, all the interface circuits of the LM940 are 1.8V CMOS logic. Only USIM interfaces are capable of dual voltage I/O. The following tables show the logic level specifications used in the LM940 interface circuits.
  • Page 33 No pull-down leakage current Table 25: Operating Range – For SIM Pins Operating at 2.85V Power On The LM940 is automatically turning on when the VBATT is supplied. 1VV0301352 Rev. 18 Page 33 of 75 2022-01-04 Not Subject to NDA...
  • Page 34 6.2.1. Initialization and Activation State After turning on the LM940 module, the LM940 is not instantly activated because the SW initialization process takes some time to complete. For this reason, it is recommended not to communicate with the LM940 during the Initialization phase.
  • Page 35 • Fast Shutdown by GPIO triggered or USB AT command AT#FASTSHDN • Unconditional Shutdown using the SYSTEM_RESET_N 6.3.1. Graceful Shutdown To shutdown the LM940 module more safely, host can use the graceful shutdown function. The graceful shutdown can be triggered by: • AT command via USB 6.3.1.1.
  • Page 36 6.3.2. Fast Shutdown For a quicker shutdown of the LM940 module, the host can use the fast shutdown function. Fast shutdown can be triggered by: • AT command via USB • GPIO 6.3.2.1.
  • Page 37 Once the Fast Shutdown Trigger senses a HIGH to LOW transition, fast shutdown is initiated. Then the LM940 module enters finalization state, terminates active processes, and prepares to turn off safely. As shown in below figure, when the module is ready to be turned off, it will be indicated via Shutdown Indicator.
  • Page 38 To turn off the module, SYSTEM_RESET_N pad must be asserted low more than 1 seconds and then it should be kept low. When the SYSTEM_RESET_N is asserted low more than 1 second, the LM940 enters finalization state and after the end of the shutdown process Shutdown Indicator will go to low.
  • Page 39 LM940 Hardware Design Guide Note: 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 it is powered OFF or during an ON/OFF transition. Warning: Not following the recommended shut-down procedures might damage the device and consequently void the warranty.
  • Page 40 LM940 Hardware Design Guide 6.4.1. Graceful Reset To gracefully restart the LM940 module, AT#REBOOT AT command must be sent via a USB communication. Figure 10: Graceful Reset by AT#REBOOT 6.4.2. Unconditional Hardware Reset To unconditionally restart the LM940 module, the SYSTEM_RESET_N pin must be asserted low more than 1 seconds and then released.
  • Page 41 Usually dying gasp feature is completed less than 1 second after triggered. This may take longer depending on network conditions. Communication Ports Below table summarizes all the hardware interfaces of the LM940 module. Interface LM940 Super-speed USB3.0 with high-speed USB2.0 USIM x2, dual voltage each (1.8V/2.85V)
  • Page 42 The USB port is typically the main interface between the LM940 module and OEM hardware. USB 3.0 needs capacitors on the TX lines in both directions for AC coupling. To interface USB3.0 with an application board of customer, 0.1uF capacitors should be installed on...
  • Page 43 LM940 Hardware Design Guide Warning: At power-up, LM940 success to enumerate SS_USB interface. But if a hot plug is attempted in case of SS_USB, then LM940 may fail to enumerate SS_USB. Below table lists the USB interface signals. Signal Function...
  • Page 44 Figure 15: ESD Protection for USB3.0 6.6.2. SIM Interface The LM940 supports two external SIM interfaces (1.8V or 2.85V). Note: LM940 HW versions 1.0 and 2.0 have a different SIM2 pinout. Below table lists the SIM interface signals. Signal Function...
  • Page 45 The following Figures illustrate in particular how the application interface should be designed. Figure 16: SIM Schematics Note: LM940 contains an internal pull-up resistor on SIMIO. It is not necessary to install external pull – up resistor. 1VV0301352 Rev. 18...
  • Page 46 1.8V Table 29: Module Control Signal 6.6.3.1. W_DISABLE_N The W_DISABLE_N signal is provided to make the LM940 goes into the airplane mode: • Enter the airplane mode: Low • Normal operating mode: High or Leave the W_DISABLE_N not connected LM940 contains an internal VBATT (Nominal 3.3V) pull-up resistor on W_DISABLE_N.
  • Page 47 Output pins can only be written or queried and set the value of the pin output. The following GPIOs are always available as a primary function on the LM940. Below table lists the GPIO signals of LM940.
  • Page 48 LM940 Hardware Design Guide 6.6.4.2. Using a GPIO Pin as Output GPIO pins, when used as outputs, can drive 1.8V CMOS digital devices or compatible hardware. When set as outputs, the pins have a push-pull output, and therefore the pull- up resistor can be omitted.
  • Page 49 GPIO_08 I/O, 1.8V Can be used as specific functions. Table 32: Not Dedicated I/O 6.6.5. I2C – Inter-Integrated Circuit The LM940 supports an I2C interface. The table below lists the LM940 I2C signals Signal Function Type Comment I2C_SCL I2C Clock CMOS 1.8V...
  • Page 50 Frequency range Depending on frequency band(s) supported by the network operator, the customer shall use the most suitable antenna for that/those band(s) The bands supported by the LM940 is provided in section 2.2 Product Variants and Frequency Bands. Impedance 50 Ohm Input power >...
  • Page 51 ECC values below 0.5 on all frequency bands are recommended. GNSS Receiver The LM940 integrates a GNSS receiver that could be used in Standalone mode and in A- GPS (assisted GPS), according to the different configurations. LM940 supports an active antenna.
  • Page 52 This allows the module to work well with a passive GNSS antenna. If the antenna cannot be located near the LM940, then an active antenna (that is, an antenna with a low noise amplifier built in) can be used with an external dedicated power supply circuit.
  • Page 53 LM940 Hardware Design Guide Figure 19: Antenna Connectors Positions http://www.hirose- For more information about mating connectors visit the website connectors.com/ 7.5.2. Antenna Cable Connecting cables between the module and the antenna must have 50 Ω impedance. If the impedance of the module is mismatched, RF performance is reduced significantly.
  • Page 54 RF exposure compliance. OEM integrators must ensure that the end user has no manual instructions to remove or install the LM940 module. Antennas used for this OEM module must not exceed gain of below table for mobile and fixed operating configurations.
  • Page 55 LM940 Hardware Design Guide 8. MECHANICAL DESIGN General The LM940 module was designed to be compliant with a standard lead-free SMT process. Moreover, it is compatible with the Mini PCIe card 52-pin card edge-type connector. Finishing and Dimensions Drawing Figure 20, shows the mechanical dimensions of the LM940 module.
  • Page 56 9. APPLICATION GUIDE Debug of the LM940 Module in Production To test and debug the mounting of the LM940 module, we strongly recommend adding several test points on the host PCB for the following purposes: • Checking the connection between the LM940 itself and the application •...
  • Page 57 LM940 Hardware Design Guide • 100uF for VBATT Please note that capacitance mainly depends on the conditions of their application board. Generally, additional capacitance is required when the power line is longer. And if customers use the fast power down function, then more bypass capacitors should be mounted on the application board.
  • Page 58 LDO out for 1.8V Power See note Note: * SIMRST2, SIMVCC2, SYSTEM_RESET_N, VREG_L6_1P8 are assigned differently to LM940 1.0 and 2.0. For more details refer to the chapter 3. Pins Allocation. Table 38: EMC Recommendations All other pins have the following characteristics: •...
  • Page 59 LM940 Hardware Design Guide 10. PACKAGING Tray The LM940 modules are packaged on trays of 20 pieces each. These trays can be used in SMT processes for pick and place handling. Figure 21: Tray Packaging 1VV0301352 Rev. 18 Page 59 of 75...
  • Page 60 LM940 Hardware Design Guide 1VV0301352 Rev. 18 Page 60 of 75 2022-01-04 Not Subject to NDA...
  • Page 61 • Approvals for major Mobile Network Operators RED Approval 11.2.1. RED Declaration of Conformity Hereby, Telit Communications S.p.A declares that the LM940 Series Modules are in compliance with Directive 2014/53/EU. The full text of the EU declaration of conformity is available at the following internet https://www.telit.com/red...
  • Page 62 LM940 Hardware Design Guide Telit n’approuve aucune modification apportée à l’appareil par l’utilisateur, quelle qu’en soit la nature. Tout changement ou modification peuvent annuler le droit d’utilisation de l’appareil par l’utilisateur. Interference statement This device complies with Part 15 of the FCC Rules and Industry Canada licence-exempt RSS standard(s).
  • Page 63 LM940 Hardware Design Guide Mode Band Antenna Gain (dBi) FDD 2600 – B7 FDD 700a – B12 FDD 700c – B13 FDD 700b – B17 FDD 1900+ – B25 FDD 850+ – B26 FDD 700d – B29 FDD 2300 WCS – B30 FDD AWS-3 –...
  • Page 64 LM940 Hardware Design Guide Labelling Requirements for the Host device The host device shall be properly labelled to identify the modules within the host device. The certification label of the module shall be clearly visible at all times when installed in the host device, otherwise the host device must be labelled to display the FCC ID and ISED of the module, preceded by the words "Contains transmitter module", or the word...
  • Page 65 LM940 Hardware Design Guide Antenna Specification In all cases assessment of the final product must be met against the Essential requirements of the RE Directive Articles 3.1(a) and (b), safety and EMC respectively, as well as any relevant Article 3.3 requirements.
  • Page 66 LM940 Hardware Design Guide 12. REFERENCE TABLE OF RF BANDS CHARACTERISTICS Mode Freq. Tx (MHz) Freq. Rx (MHz) Channels Tx-Rx Offset WCDMA 2100 – B1 1920 ~ 1980 2110 ~ 2170 Tx: 9612 ~ 9888 190 MHz Rx: 10562 ~ 10838 WCDMA 1900 –...
  • Page 67 LM940 Hardware Design Guide Mode Freq. Tx (MHz) Freq. Rx (MHz) Channels Tx-Rx Offset LTE 700 d – B29 Downlink only 717 ~ 728 Rx: 9660 ~ 9769 – LTE 2300 WCS – B30 Downlink only 2350 ~ 2360 Rx: 9770 ~ 9869 –...
  • Page 68 LM940 Hardware Design Guide 13. PRODUCT AND SAFETY INFORMATION Copyrights and Other Notices SPECIFICATIONS ARE SUBJECT TO CHANGE WITHOUT NOTICE Although reasonable efforts have been made to ensure the accuracy of this document, Telit assumes no liability resulting from any inaccuracies or omissions in this document, or from the use of the information contained herein.
  • Page 69 LM940 Hardware Design Guide computer programs, including – but not limited to - the exclusive right to copy or reproduce in any form the copyrighted products. Accordingly, any copyrighted computer programs contained in Telit’s products described in this instruction manual shall not be copied (reverse engineered) or reproduced in any manner without the express written permission of the copyright owner, being Telit or the Third-Party software supplier.
  • Page 70 LM940 Hardware Design Guide 13.2.4. Trademarks TELIT and the Stylized T-Logo are registered in the Trademark Office. All other product or service names are property of their respective owners. 13.2.5. 3rd Party Rights The software may include Third Party’s software Rights. In this case the user agrees to comply with all terms and conditions imposed in respect of such separate software rights.
  • Page 71 LM940 Hardware Design Guide Safety Recommendations Make sure 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 areas where: • it can interfere with other electronic devices, particularly in environments such as hospitals, airports, aircrafts, etc.
  • Page 72 LM940 Hardware Design Guide 14. GLOSSARY Clock CMOS Complementary Metal – Oxide Semiconductor Data Terminal Equipment Equivalent Resistance Frequency division duplex GPIO General Purpose Input Output High Speed HSDPA High Speed Downlink Packet Access HSUPA High Speed Uplink Packet Access...
  • Page 73 Correct the typo 6.6.2 SIMVCC2 : Pin 6 -> Pin 16 SIMRST2 : Pin 16 -> Pin 6 2020-08-25 Changed the description of the difference between LM940 1.0 and 2.0 Applicability Table 3.1 Pin-out 6.2 Power On 6.3.3 Unconditional Shutdown...
  • Page 74 LM940 Hardware Design Guide 2018-12-06 Updated 2 General product description 2018-04-25 Added 6.5.1 Warning Deleted Audio Section Deleted WWAN_LED_N, WAKE_N Section 2018-02-22 Updated 13 RF bands Characteristics Added 6.3 Added Warning 2017-11-01 Added 2.8 GNSS Receiver Specifications Updated 2.2.1 RF bands per Regional Variant Updated 8.3 Drawing...

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