Telit Wireless Solutions LE910C series Guide

LE910Cx mPCIe
Thermal Design Guide
1VV0301626 Rev. 2 –2021-07-09
Telit Technical Documentation

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APPLICABILITY TABLE
PRODUCTS
LE910C4-NF MPCIE
LE910C1-NF MPCIE
LE910C1-NA MPCIE
LE910C1-NS MPCIE
LE910C1-AP MPCIE
LE910C4-AP MPCIE
LE910C1-EU MPCIE
LE910C4-EU MPCIE
LE910C1-SA MPCIE
LE910C1-ST MPCIE
LE910C1-SV MPCIE
LE910C1-LA MPCIE
LE910C4-LA MPCIE
LE910C4-CN MPCIE
LE910C1-EUX MPCIE
LE910C1-SVX MPCIE
LE910C1-SAX MPCIE

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CONTENTS
APPLICABILITY TABLE 2
CONTENTS 3
1. INTRODUCTION 5
2. THERMAL MODEL 6
Temperature Sensor and Hotspot 6
2.1.1. Temperature Reading and Monitoring 7
Thermal Mitigation Algorithm 8
2.2.1. How to Change Thermal Mitigation Level Range 9
Thermal Model 13
Temperature Range 14
Current Consumption in Each Mode 14
3. THERMAL DESIGN 16
Thermal Design Guidelines 16
Thermal Design Solution 17
4. PRODUCT AND SAFETY INFORMATION 20
Copyrights and Other Notices 20
4.1.1. Copyrights 20
4.1.2. Computer Software Copyrights 20
Usage and Disclosure Restrictions 21
4.2.1. License Agreements 21
4.2.2. Copyrighted Materials 21
4.2.3. High Risk Materials 21
4.2.4. Trademarks 22
4.2.5. Third Party Rights 22
4.2.6. Waiwer of Liability 22
Safety Recommendations 23

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5. GLOSSARY 24
6. DOCUMENT HISTORY 25

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1. INTRODUCTION
This document provides a thermal model and design guidelines useful for developing a
product with the Telit LE910Cx mPCIe.
Note: Proper thermal protection design protects against damage to
people or component under 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
LE910Cx mPCIe has two thermistors inside the module. The internal temperature can be
monitored by the AT command.
Figure 1: LE910Cx mPCIe Temp Sensor & Hotspot
As you can see in the figure above, there is a temperature sensor (PA_THERM0) inside
the LE910Cx mPCIe. And it can be read by the internal temperatures using the
AT#TEMPMON command.

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2.1.1. Temperature Reading and Monitoring
AT#TEMPMON command provides several methods to read the internal temperature as
instant reports and to monitor the internal temperature using URC and GPIO.
#TEMPMON –Temperature monitor
AT#TEMPMON=
<mod>
[,<urcmode>
[,<action>
[,<GPIO>]]]
Set command sets the behavior of the module internal temperature monitor.
Parameters:
<mod>
0 - sets the command parameters.
1 - triggers the measurement of the module internal temperature, reporting the result
in the format:
#TEMPMEAS: <level>,<value>
where:
<level> - threshold level
-2 - Extreme temperature lower bound.
-1 - Operating temperature lower bound.
0 - normal temperature.
1 - Operating temperature upper bound.
2 - Extreme temperature upper bound.
(see note 1)
<value> - actual temperature expressed in Celsius degrees.
Setting of the following optional parameters has meaning only if <mod>=0:
<urcmode> - URC presentation mode. (Default 1)
0 - It disables the presentation of the temperature monitor URC.
1 - It enables the presentation of the temperature monitor URC, whenever the module
internal temperature reaches either operating or extreme levels. The unsolicited
message is in the format:
#TEMPMEAS: <level>,<value>
where:
<level> and <value> are as before.
<action> - sum of integers, each representing the action to be done whenever the
module internal temperature reaches either operating or extreme levels (default is 1).
0 - (00) - No action.
1 - (01) - Activating of thermal mitigation according to thermal configuration file.
2 - (10) - Output pin <GPIO> is tied HIGH when operating temperature bounds are
reached; when the temperature is back to normal the output pin <GPIO> is tied LOW. If
this <action> is required, it is mandatory to set the <GPIO> parameter too.
3- (11) - This value contains <action=1> and <action=2> i.e. activate thermal mitigation
and a GPIO indication. If this <action> is required, it is mandatory to set the <GPIO>
parameter too.
<GPIO> - GPIO number. Valid range is any TGPIO pin as described in #GPIO command.
This parameter is needed and required only if <action>=2 or 3 are enabled.
AT#TEMPMON?
Read command reports the current parameter settings for #TEMPMON command in
the format:
#TEMPMON: <urcmode>,<action> [,<GPIO>]

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#TEMPMON –Temperature monitor
AT#TEMPMON=?
Test command reports the supported range of values for parameters <mod>,
<urcmode>, <action>, and <GPIO>
Notes
1. Thresholds levels are defined in #TEMPCFG command. See there for detailed
description on thermal mitigation configuration.
2. Last <action> setting is saved in the 'config.ini' file ('mitigate'/'none mitigate'), and
in the NVM ('gpio indication'/'none gpio indication').
3. Last <GPIO> is saved in the NVM.
4. Thermal mitigation is disabled automatically when using laboratory test SIM.
Table 1: #TEMPMON –Temperature Monitor
Thermal Mitigation Algorithm
LE910Cx mPCIe 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 temperature sensor.
The thermal mitigation algorithm limits the performance (UL throttling, Tx power back
off, call drop.. and so on) when the temperature is above a defined certain level.
Thermal Mitigation Level
The temperature sensor has several levels of thermal mitigation. Each level has
predefined actions as below table and works in sensor individually.
Performs the following actions according to mitigation level to reduce/control the
temperature.
Sensor
Level
Action
Comment
PA_THERM
0
-
Normal
1
Enable MTPL back-off
Limit maximum Tx power (23dBm)
2
Emergency Calls Only
Table 2: Thermal Mitigation Level
After entering mitigation level 2, the device will register on the network after PA_THERM
sensor reaches mitigation level 0. In other words, the sensor reading falls below the level
1 clear thresholds.

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2.2.1. How to Change Thermal Mitigation Level Range
Thermal mitigation level range and action could be modified through AT#TEMPCFG
command.
AT#TEMPCFG=
<etlz_clr>,<etlz>
,<etlz_act_in>,
<otlz_clr>,<otlz>
,<otlz_act_in>,
<otnz_clr>,<otnz>,<otnz_
act_in>,
<otuz_clr>,<otuz>,<otuz_
act_in>,
<etuz_clr>,<etuz>,<etuz_
act_in>
Set command sets the Temperature zones used in the #TEMPMON command.
Parameters:
<etlz_clr>: Extreme low zone temperature threshold clear. Has only one valid value: -
273°C. see notes
<etlz>: Extreme low zone temperature threshold. Default value -33°C.
<etlz_act_in>: Extreme low zone action info. Default value 0.
<otlz_clr>: Operate low zone temperature threshold clear. Default value -35°C.
<otlz>: Operate low zone temperature threshold. Default value -28°C.
<otlz_act_in >: Operate low zone action info. Default value 0.
<otnz_clr>: Operate normal zone temperature threshold clear. Default value -30°C.
<otnz>: Operate normal zone temperature threshold. Default value 97°C.
<otnz_act_in>: Operate normal zone action info. Default value 0.
<otuz_clr>: Operate up zone temperature threshold clear. Default value 95°C.
<otuz>: Operate up zone temperature threshold. Default value 102°C.
<otuz_act_in>: Operate up zone action info. Default value 2.
<etuz_clr>: Extreme up zone temperature threshold clear. Default value 100°C.
<etuz>: Extreme up zone temperature threshold. Has only one valid value: 528°C.
see notes
<etuz_act_in>: Extreme up zone action info. Default value 3.
See notes for detailed description of thermal mitigation configuration.
AT#TEMPCFG?
Read command reports the current parameter setting for #TEMPCFG command in the
format:
#TEMPCFG:
<etlz_clr>,<etlz>,<etlz_act_in>,<otlz_clr>,<otlz>,<otlz_act_in>,<otnz_clr>,<otnz>,<otnz
_act_in>,<otuz_clr>,<otuz>,<otuz_act_in>,<etuz_clr>,<etuz>,<etuz_act_in>
AT#TEMPCFG =?
Test command reports the supported range values for parameters
<x_clr>,<x>,<x_action_info>.
Where "x" is substitute for "etlz", "otlz", "otnz", "otuz", "etuz".
Values are:
#TEMPCFG: (-40-102),(-40-102),(0-5)
Table 3: #TEMPCFG –Temperature Monitor Configuration
Note: After setting new values, it is necessary to execute the power
cycle or #REBOOT command in order the mitigation algorithm will
operate from them.
#TEMPCFG –Temperature Monitor Configuration

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Thermal mitigation mechanism works like this:
The whole temperature scale is divided into 5 states (zones).
Each temperature measured should belong to a particular state called "current state".
State is defined by the following fields:
"thresholds" –upper temperature boundary of the state. Values are in °C.
"thresholds_clr" –lower temperature boundary of the state. Values are in °C.
"actions" –indicator that indicates if an action should be taken or not in the "current
state". Values are: "none"/"mitigate".
"action_info" –thermal mitigation action type that should be taken care if "actions" field
is "mitigate".
Values are:
0 - No mitigation action is required.
1 - Mitigation action - data throttling (reducing uplink baud rate).
2 - Mitigation action - TX backoff (reducing MTPL - Max Tx Power Limit).
3 - Emergency Calls Only.
4 - RF OFF. RX and TX circuits automatically disabled (using +CFUN=4).
5 - Automatic shutdown. Module is powered off.
There are five limitations on setting temperature and actions, in-order to keep module
safety.
•The User is prohibited from setting an "automatic shutdown" action to ‘operate the
normal zone’.
•The User is prohibited from setting a “no mitigation” or "data throttling" action to
“operate up the zone”.
•The User is prohibited from setting a "no mitigation" or "data throttling" or "tx
backoff" action to “extreme up zone”.
•The User is prohibited from setting the “normal zone” above 97deg.
•If the module enters into a state of "emergency only" calls, it registers to a regular
call, only when the module returns to "no mitigation" state.
•An error message “+CME ERROR: operation not supported” will be received in
response.

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Here is the graph illustrating the temperatures configuration.
Figure 2: Temperatures Configuration
When temperature exceeds the "current state" "threshold", the thermal mitigation
algorithm searches for the next state in which this temperature is below its "threshold".
Once it is found it, the "current state" is updated to that "state" and then checks if "action"
is "mitigate"; if so, then activates the mitigation according to the "action info" of the
"current state".
When temperature decreases below "threshold_clr" it executes the same algorithm as
above, but in the opposite direction. It searches the next state where this temperature is
greater than its " threshold_clr ", updates the "current state" to that state, and activates
mitigation as described above.
There are 2 rules that the states definition should obey:
1. Overlap between 2 adjacent states of at least 2 deg, i.e. ( "thre state(x)" –"thre_clr
state(x+1)" ) >= 2
2. Each state shall have a "free" temperature range that is not part of any overlap
range. This range should be at least 2 deg, i.e. ( "thre_clr(x+2)" –"thre(x)" ) >= 2 .
Rule '1' comes to ensure hysteresis in the transition between two states.
Rule '2' comes to ensure a minimum range for a stable state.
State 0 is 'Extreme low zone'.
State 1 is 'Operate low zone'.
State 2 is 'Operate normal zone'.
State 3 is 'Operate up zone'.
State 4 is 'Extreme up zone'.
Thre 3
State 0
State 1
State 2
State 3
State 4
thr_clr 0
thr_clr 1
thr_clr 3
thr_clr 2
thr_clr 4
Thre 0
Thre 1
Thre 2
Thre 4

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etlz_clr –Extreme low zone threshold clear is enforced to have value of '-273'. The
Module does not operate at this temperature, but this value is logically set to clearly
define the 'thermal state' at temperatures below -40 deg.
etuz –Extreme up zone threshold is enforced to have the value '528'. The Module does
not operate at this temperature, but this value is logically set clearly define the 'thermal
state' at temperatures above 102 deg.
"#TEMPMON" set command, changes field "actions" to "mitigate" or "none" to all zones.
All above parameters are saved in a configuration file in the module file system.
Examples:
AT#TEMPCFG=-273,-33,3,-35,-28,2,-30,80,0,78,90,3,88,528,3
OK
Explain:
Zone
Thr_clr
Thr
Action Info
'Extreme low zone'
-273
-33
3 –emergency call only
'Operate low zone'
-35
-28
2 –TX backoff
'Operate normal zone'
-30
80
0 –no mitigation
'Operate up zone'
78
90
3 - emergency call only
'Extreme up zone'
88
528
3 - emergency call only
Table 4: Example of a Normal SW Setup
All zones have hysteresis and free temperature range.
AT#TEMPCFG=-273,-33,3,-35,-28,2,-30,80,0,79,90,3,88,528,3
+CME ERROR: operation not supported
Explain:
Zone
Thr_clr
Thr
Action Info
'Extreme low zone'
-273
-33
3 –emergency call only
'Operate low zone'
-35
-28
2 –TX backoff
'Operate normal zone'
-30
80
0 –no mitigation
'Operate up zone'
79
90
3 - emergency call only
'Extreme up zone'
88
528
3 - emergency call only
Table 5: Example SW Setup Error (1)
('Thr' of 'Operate normal zone') - ('Thr_clr' of 'Operate up zone') = 1 < 2
Rule 1 was braked - Hysteresis is lesser than 2 deg.

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AT#TEMPCFG=-273,-33,3,-35,-28,2,-30,80,0,78,90,3,81,528,3
+CME ERROR: operation not supported
Explain:
Zone
Thr_clr
Thr
Action Info
'Extreme low zone'
-273
-33
3 –emergency call only
'Operate low zone'
-35
-28
2 –TX backoff
'Operate normal zone'
-30
80
0 –no mitigation
'Operate up zone'
78
90
3 - emergency call only
'Extreme up zone'
81
528
3 - emergency call only
Table 6: Example SW Setup Error (2)
('Thr_clr' of 'Extreme up zone') - ('Thr' of 'Operate normal zone') = 1 < 2
Rule 2 was braked - free temperature range is lesser then 2 deg.
Note: • After moving to zone with activity 3 (emergency call only),
only when moving to zone with activity 0 (no mitigation) the
device will register to the network.
•<action> for the high-zone cannot be <no action> or <data
throttling>.
•<action> for extreme high zone cannot be <no action> or
<data throttling> or <tx backoff>.
Thermal Model
Thermal Model is evaluated by thermal simulation and RF test with a thermal chamber.
Figure 3: Equivalent Thermal Resistance Model

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The two-resistor compact model is calculated according to JEDEC standard.
ƟJT is the thermal resistance from junction to the top side: 8 °C/W
ƟTA is the thermal resistance from the top side to the air side: 25 °C/W
ƟJB is the thermal resistance from junction to the bottom side: 4 °C/W
ƟBA is the thermal resistance from the bottom to the air side: 17 °C/W
**Measure condition:
•Thermal resistances were measured on a 100mm * 90mm * 1mm FR4 Evaluation
board
•Network condition
Downlink 2*2MIMO 150Mbps throughput (B71)
Uplink QPSK and maximum power status
Temperature Range
The maximum operating temperature allowed is +105°C which can be read from
AT#TEMPMON. It is not recommended to operature the LE910Cx mPCIe above the
allowable maximum operating temperature.
Operating Condition
Condition
Min
Typ
Max
The Temperature read by AT#TEMPMON=1
-
-
+105°C
Table 7: Temperature Range
Current Consumption in Each Mode
LE910Cx mPCIe Current Consumption
IDLE Mode
CFUN=1
30mA
No call connection
USB3.0 is connected to a host
Operative Mode (LTE)
Non-CA mode (1DL /
1UL)
750mA
Non-CA, Band 71, Single carrier, BW 20MHz, 22dBm, 12RB
Operative Mode (WCDMA)
WCDMA Voice
650 mA
WCDMA voice call (Tx = 23 dBm)
WCDMA HSPA (22 dBm)
650 mA
WCDMA data call (Cat4, Max Throughput)
Table 8: LE910Cx mPCIe Current Consumption
Mode
Average [Typ.]
Mode Description

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* Worst/best case current values depend on the network configuration
** Loop-back mode in call equipment
*** 3.3 voltage / room temperature
Note: 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 customer thermal design guide to help their thermal design.
Thermal Design Guidelines
To enhance heat dissipation:
•Ensure that there is sufficient air flow around the LE910Cx mPCIe. (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 LE910Cx mPCIe directly.
•Use Thermal Interface Material. (Spread the heat)
- Eliminate air gaps between the top/bottom of LE910Cx mPCIe and the 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 LE910Cx
mPCIe.
•If the thermal conductive material is attached between LE910Cx mPCIe and the
customer board, the heat dissipation is better for multilayer PCB.
•Attach the conductive material and the heat sink at top and bottom sides of the
module for the heat dissipation.

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Thermal Design Solution
There are the LE910Cx mPCIe for the heat dissipation.
Figure 4: LE910Cx mPCIe Side View
RF and Baseband areas must be heat dissipation.
Figure 5: Copper Pad Location on Bottom of LE910Cx mPCIe
On the back of the LE910Cx mPCIe there is the large solder resist opening area for the
better heat dissipation to heat sinks found 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. LE910Cx mPCIe is able of getting very hot when operating at the upper
limit of its range.
A heat sink or TIM is a component attached to a module to transfer 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.

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Figure 6: Thermal Solution on Both sides
The best method is to connect a heat sink on the top and a TIM on the bottom side.
Inevitable environment where the heat sink or TIM cannot be fixed on both sides, it is able
to attach a heat sink or TIM only one side, but this is not the best option.
It is recommended to connect a TIM pad to the bottom side of customer PCB.
Please refer to the figure as below.
Figure 7: Heat Sink on Top Side
Figure 8: TIM on Bottom Side

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Note: If the above contents are ignored, the network connection
might be terminated due to overheating. When the temperature
drops, the network connection will be restarted.

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4. 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. The information contained in this
document has been carefully checked and is believed to be reliable. Telit reserves the
right to make changes to any of the products described herein, to revise it and to make
changes from time to time without any obligation to notify anyone of such revisions or
changes. Telit does not assume any liability arising from 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.
This document may contain references or information about Telit’s products (machines
and programs), or services that are not announced in your country. Such references or
information do not necessarily mean that Telit intends to announce such Telit products,
programming, or services in your country.
4.1.1. Copyrights
This instruction manual and the Telit products described herein may include or describe
Telit’s copyrighted material, such as computer programs stored in semiconductor
memories or other media. The laws in Italy and in other countries reserve to Telit and its
licensors certain exclusive rights for copyrighted material, including the exclusive righ to
copy, reproduce in any form, distribute and make derivative works of the copyrighted
material. Accordingly, any of Telit’s or its licensors’ copyrighted material contained
herein or described in this instruction manual, shall not be copied, reproduced,
distributed, merged or modified in any way without the express written permission of the
owner. Furthermore, the purchase of Telit products shall not be deemed to grant in any
way, neither directly nor by implication, or estoppel, any license.
4.1.2. Computer Software Copyrights
Telit and the Third Party supplied Software (SW) products, described in this instruction
manual may include Telit’s and other Third Party’s copyrighted computer programs
stored in semiconductor memories or other media. The laws in Italy and in other
countries reserve to Telit and other Third Party SW exclusive rights for copyrighted