LM960 Thermal Design Guide - Telit: IoT Solutions Provider

[01.

2019

]

Mod.0818 2019-01 Rev.0

LM960 Thermal Design Guide

1VV0301620 Rev. 1 – 2019-11-11


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SPECIFICATIONS ARE 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 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.


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USAGE AND DISCLOSURE RESTRICTIONS

I. 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.

II. 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

III. 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.

IV. 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.

V. Third Party Rights

The software may include Third Party Right software. In this case you agree to comply with all terms and conditions imposed on you in respect of such separate software. In addition to Third Party Terms, the disclaimer of warranty and limitation of liability provisions in this License shall apply to the Third Party Right software. TELIT HEREBY DISCLAIMS ANY AND ALL WARRANTIES EXPRESS OR IMPLIED FROM ANY THIRD PARTIES REGARDING ANY SEPARATE FILES, ANY THIRD PARTY MATERIALS INCLUDED IN THE SOFTWARE, ANY THIRD PARTY MATERIALS FROM WHICH THE SOFTWARE IS DERIVED (COLLECTIVELY “OTHER CODE”), AND THE USE OF ANY OR ALL THE OTHER CODE IN CONNECTION WITH THE SOFTWARE, INCLUDING (WITHOUT LIMITATION) ANY WARRANTIES OF SATISFACTORY QUALITY OR FITNESS FOR A PARTICULAR PURPOSE. NO THIRD PARTY LICENSORS OF OTHER CODE SHALL HAVE ANY LIABILITY FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING WITHOUT LIMITATION LOST PROFITS), HOWEVER CAUSED AND WHETHER MADE UNDER CONTRACT, TORT OR OTHER LEGAL THEORY, ARISING IN ANY WAY OUT OF THE USE OR DISTRIBUTION OF THE OTHER CODE OR THE EXERCISE OF ANY RIGHTS GRANTED UNDER EITHER OR BOTH THIS LICENSE AND THE LEGAL TERMS APPLICABLE TO ANY SEPARATE FILES, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.


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APPLICABILITY TABLE

PRODUCTS

LM960 LM960A18


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Contents

NOTICE 2

COPYRIGHTS ................................................................................................ 2

COMPUTER SOFTWARE COPYRIGHTS ...................................................... 2

USAGE AND DISCLOSURE RESTRICTIONS ............................................... 3

APPLICABILITY TABLE ................................................................................ 4

CONTENTS .................................................................................................... 5

1. INTRODUCTION .......................................................................... 6

2. THERMAL MODEL ...................................................................... 7 Temperature Sensor and Hotspot ................................................. 7

2.1.1. Temperature Reading and Monitoring ........................................... 7 Thermal Mitigation Algorithm ........................................................ 9

2.2.1. Thermal Mitigation Level Reading ............................................... 10 2.2.2. How to Change Thermal Mitigation Level Range ........................ 12

Thermal Model -TBD .................................................................. 14 Temperature Range .................................................................... 15 Current consumption in each mode ............................................ 15

3. THERMAL DESIGN ................................................................... 17 Thermal Design Guidelines ......................................................... 17 Thermal Design Solution ............................................................. 18

4. DOCUMENT HISTORY .............................................................. 21


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1. INTRODUCTION The aim of this document is to provide thermal model and design guidelines useful for developing a product with the Telit LM960.

Information – Proper thermal protection design protects against human or component damage for worst-case conditions. And it reduces the probability of failure and does not adversely affect the use of the module, and greatly extends the operation time with maximum performance.


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2. THERMAL MODEL

Temperature Sensor and Hotspot LM960 has three thermistors inside the module. The internal temperature can be monitored by the AT command.

<LM960 Temp Sensor & Hotspot>

As you can see in the figure above, there are three temperature sensors (TSENS2, PA_THERM0, PA_THERM1) inside the LM960. And it can be read by the internal temperatures using the AT#TEMPSENS command.

2.1.1. Temperature Reading and Monitoring AT#TEMPSENS command provides several methods to read the internal temperature like instantaneous or periodic reporting and to monitor the internal temperature using URC and GPIO.

#TEMPSENS – Temperature monitor

AT#TEMPSENS= <mod>[,<interval>

Set command sets the operation of the internal temperature monitor.


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#TEMPSENS – Temperature monitor [,<action> ,<low_temp> ,<high_temp> [,<gpio>]]]

Parameters: <mod> 0 – disables the periodic reporting (factory default) 1 – enables the periodic reporting 2 – instantaneous reporting of the Temperature

Note: the module cannot enter sleep when <mod>=1. <interval> - duration in seconds of the interval between next measurement. It has meaning only if <mod> is 1. The unsolicited message is in the format:

#TEMPSENS: <sensor>,<value> where: <sensor> - temperature sensor name <value> - actual temperature expressed in Celsius degrees

<action> 1 - (01) - it enables the presentation of the temperature monitor URC periodically. If <action> is not specified, this is default. 2 - (10) - it enables the presentation of the temperature notification URC, whenever the module internal temperature reaches either <low_temp> or <high_temp> levels. 4 - (100) - output pin <gpio> is tied HIGH when set temperature bounds are reached; when the temperature is back to normal the output pin <gpio> is tied LOW. It is mandatory to set the <gpio> parameter too to set this <action>. The notification message is in the format:

#TEMPNOTI: <level>,<value> where: <level> - threshold level -1 - <low_temp> set temperature lower bound 0 - normal temperature 1 - <high_temp> set temperature upper bound

Note: Possible values for the parameter <action> are form 1 to 7 (001, 010, 011, 100, 101, 110 and 111)


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#TEMPSENS – Temperature monitor

<low_temp> - Temperature Lower Bound (-40 – 0, Celsius Degrees) <high_temp> - Temperature Upper Bound (0 – 100, Celsius Degrees) <gpio> - GPIO number. Valid range is any GPIO pin as described in #GPIO command. This parameter is needed and required only if <action>=4, 5, 6 or 7 are enabled.

AT#TEMPSENS? Read command reports the current parameter settings in the format: #TEMPSENS: <mod>,<interval>[,<action>,<low_temp>,<high_temp>,[<gpio>]]

AT#TEMPSENS=?

Test command reports supported range of values for parameters <mod>,<interval>,<action>,<low_temp>,<high_temp> and <gpio>.

Example AT#TEMPSENS=2 #TEMPSENS: TSENS2,29 #TEMPSENS: PA_THERM0,30 #TEMPSENS: PA_THERM1,30 OK

Thermal Mitigation Algorithm LM960 has built-in thermal mitigation algorithm to reduce the probability of failure and extend the operation time with maximum performance. The thermal mitigation algorithm operates according to the internal temperature value read through the three temperature sensors. Thermal mitigation algorithm limits the performance(DL/UL throttling, Tx power back off, call drop.. etc) when the temperature is above a defined certain level. Thermal Mitigation Level Temperature sensors have several thermal mitigation levels. Each level has predefined actions as below table and it work in sensor individually. Performs following actions according to mitigation level to reduce/control temperature.


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Sensor Level Action Comment

PA_THERM 0 - Normal

1 Enable UL data throttling Start throttling the uplink data rate by reporting a smaller buffer status report.

2 Enable MTPL back-off Limit maximum Tx power (23dBm)

3 Lmitied service mode Call released.

TSENS 0 - Normal

1 Start DL data throttling #3DL CA drops to 1DL (PCC only)

3 Limited service mode Call released.

After entering mitigation level 3, limited service mode is released after PA_THERM and TSENS sensor reaches mitigation level 0. That is, the sensor reading falls below the level 1 clear thresholds.

2.2.1. Thermal Mitigation Level Reading AT#TMLVL command used for read current thermal mitigation level of each temperature sensors.

#TMLVL – Thermal Mitigation Level

AT#TMLVL=<device_id>

Set command reports a current thermal mitigation level of specific <device_id>. Parameters: <device_id> - which device to get mitigation level 1 – TSENS2 2 – PA_THERM The report message is in the format: #TMLVL: <level> Where: <level> - thermal mitigation level 0 – normal 1 – level1 2 – level2 3 – level3


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#TMLVL – Thermal Mitigation Level Note : level2 is shown only with PA_THERM device.

AT#TMLVL? Read command reports a current thermal mitigation level of all devices in the format: #TMLVL: TSENS2,<level> #TMLVL: PA_THERM,<level>

AT#TMLVL=? Test command returns the supported range of values for parameter <device_id>.

Example AT#TMLVL? #TMLVL: TSENS2,1 #TMLVL: PA_THERM,1 OK AT#TMLVL=2 #TMLVL: 1 OK


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2.2.2. How to Change Thermal Mitigation Level Range Thermal mitigation level range could be modified through thermal engine configuration file. For using ADB on Windows OS Download the ADB tool through google (Can be skipped if you already have). http://adbshell.com/downloads

Check ADB device detection. Connect USB to Windows Laptop. Run Command Prompt or PowerShell of Windows in downloaded ADB tool

directory. adb devices

If ADB detection success, you can see the specific device id. In case of detection failed, please do next step.

Register Telit USB VID to ADB tool (This step needs only once at one Laptop. If ADB detection filed, please do following commands.

echo 0x1BC7 >> %HOMEPATH%\.android\adb_usb.ini adb kill-server adb devices

http://adbshell.com/downloads


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After do commands, you can see ADB device that attached on Laptop.

Change thermal engine configuration file Current thermal engine configuration file can be got from LM960 through ADB command. adb pull /etc/thermal-engine.conf

Open and edit the thermal-engine.conf file. Put the modified thermal-engine.conf file to LM960.

adb push thermal-engine /etc

Please do reboot LM960 to apply your changes.


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Thermal Model -TBD Thermal Model is evaluated by thermal simulation and RF test with thermal chamber.

<Equivalent thermal resistance model>

The two-resistor compact model is calculated according to JEDEC standard. ƟJT is the thermal resistance from junction to the top side: 9 °C/W ƟJA is the thermal resistance from the top side to the air side: 22 °C/W ƟJB is the thermal resistance from junction to the bottom side: 7 °C/W ƟBA is the thermal resistance from the bottom to the air side: 19 °C/W **Measure condition:

- Thernal resistances were measured in 100mm * 90mm * 1mm FR4 Evaluation board

- Network condition Downlink 4*4MIMO 1.2Gbps throughput (B2, B66C) Uplink QPSK and maximum power status

And we also provide the FloTHERM detail modeling file for help customers to design and simulate their design easily. Thermal simulation was performed with Flotherm V12.1 If you want to get the thermal simulation file, please contact Telit Technical Support at

• [email protected] • [email protected] • [email protected] • [email protected]

mailto:[email protected]




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Temperature Range The allowable maximum operating temperature is +105°C which can be read by AT#TEMPSENS. It is not recommended to operature LM960 above the allowable maximum operating temperature. Operating Condition

Condition Min Typ Max

The Temperature read by AT#TEMPSENS - - +105°C

Current consumption in each mode LM960 Current Consumption

Mode Average [Typ.] Mode Description

IDLE Mode

CFUN=1 20mA No call connection USB3.0 is connected to a host

Power Saving Mode (PSMWDISACFG=1, W_DISABLE_N:Low)

CFUN=4 2.5mA Tx and Rx are disabled; module is not registered on the network (Flight mode)

WCDMA 3mA DRx7 (1.28 sec DRx cycle)

LTE 3.3mA Paging cycle #128 frames (1.28 sec DRx cycle)

Operative Mode (LTE)

Non-CA mode (1DL / 1UL) 600mA Non-CA, Band 2, Single carrier, BW 5MHz,

23dBm, 1RB

2DL CA with 2x2 MIMO / 2UL CA 900mA

CA_2A-5A, 2x2 MIMO, Full RB, 256QAM DL / 64QAM UL (FDD 300Mbps DL / 150Mbps UL)

5DL CA with 2x2 MIMO / 1UL 1000mA

CA_2A-5B-66A-66A, 2x2 MIMO, Full RB, 256QAM DL / 64QAM UL (FDD 1Gbps DL / 75Mbps UL)

3DL CA with 4x4 MIMO / 1UL 1200mA

CA_2A-66C, 4x4 MIMO, Full RB, 256QAM DL / 64QAM UL (FDD 1.2Gbps DL / 75Mbps UL)

Operative Mode (WCDMA)

WCDMA Voice 750 mA WCDMA voice call (Tx = 23 dBm)


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Mode Average [Typ.] Mode Description

WCDMA HSPA (22 dBm) 650 mA WCDMA data call (DC-HSDPA up to 42

Mbps, Max Throughput)

* Worst/best case current values depend on network configuration ** Loop-back mode in call equipment *** 3.3 voltage / room temperature

Information – The electrical design for the power supply must ensure a peak current output of at least 2A.


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3. THERMAL DESIGN This chapter provides the thermal design guide for customer to help their thermal design.

Thermal Design Guidelines To enhance heat dissipation:

• Ensure that the air flow around the LM960 is sufficient. (Spread the heat)

- Balance the heat flow between front and back of the PCB

- Insulate hot spots on the device skin from hot areas below

• Separate hottest components (Spread the heat)

• Optimize the ground plane and connections. (Spread the heat)

- Use larger copper weight for a solid ground plane layer

- Connect each ground pad of LM960 directly.

• Use Thermal Interface Material. (Spread the heat)

- Eliminate air gaps between the top/bottom of LM960 and heat spreaders;

use TIM under compression and thermal grease for better thermal

conduction

- Use large surface areas with high thermal conductivity

• Use phase change material or heat pipes. (Absorb the heat)

• Keep the TCXO or any XO away from heat sources/gradients near the LM960.

• If the thermal conductive material is attached between LM960 and the customer

board, the heat dissipation is better for multilayer PCB.

• Attach the conductive material and heat sink at top and bottom side of module for

the heat dissipation.


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Thermal Design Solution There are the 1.2 W/m-k thermal conductive materials between main chipset and shield cover of the LM960 for the better heat dissipation.

<LM960 Side View>

RF and Baseband areas must be heat dissipation.

<LM960 Shield Cover with TIM (Bottom View)>

<Copper Pad Location on Bottom of LM960>


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There is the large solder resist opening area on the back of LM960 for the better heat dissipation to heat sinks which are on a customer’s application board. This chapter defines the heat sink or TIM for your application as a basic element of the heat sink design. LM960 is able to get very hot when operating at the upper limit of its range. A heat sink or TIM is a component that is attached to a module for the sake of transferring heat from the device into the surrounding environment. This environment is most commonly air, but it can also be other fluids. Heat sinks are typically made of aluminum or copper. It expedites the heat transfer to the surrounding fluid.

<Thermal Solution on Both sides>

The best method is that attaching a heat sink on top and a TIM on bottom side.

Inevitable environment where heat sink or TIM cannot be attached to both sides, it is able to attach a heat sink or TIM only one side, but this is not the best option.

We recommend that you attach a TIM pad to the bottom side of customer PCB.

Please refer to the figure as below.

<Heat Sink on Top Side>


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<TIM on Bottom Side>

Information – If ignore the above contents, network connection might be terminated due to overheating. When the temperature drops, it will be restart the network connection.


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4. DOCUMENT HISTORY

Revision Date Changes

0 2019-08-02 Initial Release

1 2019-11-11 Applicability table – Added LM960A18

[01.

2019

]

Mod.0818 2019-01 Rev.0

LM960 Thermal Design Guide - Telit: IoT Solutions Provider

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Transcript of LM960 Thermal Design Guide - Telit: IoT Solutions Provider