Telit Wireless Solutions LE915A P Series Guide

M
o
d
.
LE915Ax-P
HW Design Guide
1VV0301680 Rev. 2 –2021-10-04
Telit Technical Documentation

LE915Ax-P Hardware Design Guide
1VV0301680 Rev. 2 Page 2of 51 2021-10-04
Not Subject to NDA
APPLICABILITY TABLE
PRODUCTS
LE915A6-P
LE915A4-P

LE915Ax-P Hardware Design Guide
1VV0301680 Rev. 2 Page 3of 51 2021-10-04
Not Subject to NDA
CONTENTS
APPLICABILITY TABLE 2
CONTENTS 3
1. INTRODUCTION 6
Scope 6
Audience 6
Contact Information, Support 6
Symbol Conventions 7
Related Documents 7
2. GENERAL PRODUCT DESCRIPTION 8
Overview 8
Cellular Frequency Bands and CA Combinations 8
2.2.1. Frequency Bands 8
2.2.2. Carrier Aggregation (LE915A6-P only) 8
Target Market 8
Main Features 9
TX Output Power 9
RX Sensitivity 9
Mechanical Specifications 10
2.7.1. Dimensions and LCC Pads Layout 10
2.7.2. Weight 10
Temperature Range 10
3. PINS ALLOCATION 11
Pin-out 11
4. POWER SUPPLY 16
Main Power Supply Requirements 16
Power Consumption (Typical) 16
1.8V Power Output 17
General Design Rule 17
4.4.1. Electrical Design Guidelines 17

LE915Ax-P Hardware Design Guide
1VV0301680 Rev. 2 Page 4of 51 2021-10-04
Not Subject to NDA
4.4.1.1. +5V Source Power Supply Design Guidelines 17
4.4.2. Thermal Design Guidelines 18
4.4.3. Power Supply PCB Layout Guidelines 18
5. INTERFACE DETAILS 21
Power On.Off and Reset Control 21
5.1.1. Power On Sequence 21
5.1.2. Power Off Sequence 21
Communication Ports 22
5.2.1. USB 2.0 Interface 22
5.2.2. UART Interfaces 23
5.2.2.1. RS232 Level Translation 25
General Purpose I/O 26
LED Indication 27
External SIM Holder 27
Reserved Pins 28
6. RF SECTION 29
Antenna Requirements 29
6.1.1. PCB Design Guidelines 29
6.1.2. PCB Guidelines in Case of FCC Certification 30
6.1.2.1. Transmission Line Design 31
6.1.2.2. Transmission Line Measurements 31
6.1.2.3. Antenna Installation Guidelines 33
7. MECHANICAL DESIGN 34
Drawing 34
8. APPLICATION PCB DESIGN 35
PCB Pad Design 35
Solder Reflow 35
Inspection 37
9. PACKAGING 38
Reel 38
Carrier Tape Detail 38

LE915Ax-P Hardware Design Guide
1VV0301680 Rev. 2 Page 5of 51 2021-10-04
Not Subject to NDA
Packaging Detail 39
Moisture Sensitivity 39
10. REGULATORY APPROVAL 41
11. PRODUCT AND SAFETY INFORMATION 45
Copyrights and Other Notices 45
11.1.1. Copyrights 45
11.1.2. Computer Software Copyrights 45
Usage and Disclosure Restrictions 46
11.2.1. License Agreements 46
11.2.2. Copyrighted Materials 46
11.2.3. High Risk Materials 46
11.2.4. Trademarks 47
11.2.5. Third Party Rights 47
11.2.6. Waiver of Liability 47
Safety Recommendations 48
12. GLOSSARY 49
13. DOCUMENT HISTORY 50

LE915Ax-P Hardware Design Guide
1VV0301680 Rev. 2 Page 6of 51 2021-10-04
Not Subject to NDA
1. INTRODUCTION
Scope
This document introduces the Telit LE915Ax-P family and presents possible and
recommended hardware solutions for the development of a product based on the
LE915Ax-P modules.
In this document all the basic functions of the module will be considered; for each of them
a suitable hardware solution will be suggested and eventually the wrong solutions and
common errors to be avoided will be evidenced. This document cannot embrace all
hardware solutions and products that may be designed. The information provided should
be used as a guide and starting point to successfully develop your product with the Telit
LE915Ax-P modules.
Information: The Integration of LTE/CBRS LE915Ax-P cellular
modules in single mode within a user application must be performed
according to the design rules described in this manual.
The information presented in this document is believed to be accurate and reliable.
However, no responsibility is assumed by Telit Communications S.p.A. for its use, nor any
infringement of patents or other rights of third parties which may result from its use. No
license is granted by implication or otherwise under any patent rights of Telit
Communications S.p.A. other than for circuitry embodied in Telit products. This
document is subject to change without notice.
Audience
This document is intended for system integrators that are using the Telit LE915Ax-P
family in their products.
Contact Information, Support
For technical support and general questions please e-mail:
• TS[email protected]
• TS[email protected]
• TS[email protected]
• TS[email protected]

LE915Ax-P Hardware Design Guide
1VV0301680 Rev. 2 Page 7of 51 2021-10-04
Not Subject to NDA
• TS[email protected]
Alternatively, use:
https://www.telit.com/contact-us/
Product information and technical documents are accessible 24/7 on our web site:
https://www.telit.com
Symbol Conventions
Danger: This information MUST be followed or catastrophic
equipment failure or personal injury may occur.
Warning: Alerts the user on important steps about the module
integration.
Note/Tip: Provides advice and suggestions that may be useful when
integrating the module.
Electro-static Discharge: Notifies the user to take proper grounding
precautions before handling the product.
Table 1: Symbol Conventions
All dates are in ISO 8601 format, that is YYYY-MM-DD.
Related Documents
•LE915Ax-P family AT command reference guide, 80671ST11047A
•LE915Ax-P family Software User Guide, 1VV0301685

LE915Ax-P Hardware Design Guide
1VV0301680 Rev. 2 Page 8of 51 2021-10-04
Not Subject to NDA
2. GENERAL PRODUCT DESCRIPTION
Overview
The LE915Ax-P family consists of an LTE CAT-6 and CAT-4 modules and is specifically
designed to enable cellular data connectivity on CBRS networks operating on TDD LTE
band 48 in US. It can also operate on other networks operating on LTE bands 42 and 43.
This document provides technical information about LE915Ax-P LCC modules.
Cellular Frequency Bands and CA Combinations
2.2.1. Frequency Bands
Following the list of operating frequencies on LTE mode.
E-UTRA Band
Freq. (MHz)
UL/DL Frequency (MHz)
Duplex Mode
42
3500
3400 –3600
TDD
43
3700
3600 –3800
TDD
48
3500
3550 - 3700
TDD
Table 2: Frequency bands supported
2.2.2. Carrier Aggregation (LE915A6-P only)
Following the list of 2CC configurations available on LTE915A6-P.
Applicable model
2CC DL CA Combinations
LE915A6-P
CA_42A-42A; CA_43A-43A; CA_48A-48A; CA_42A-43A; CA_42C; CA_43C; CA_48C
Table 3: Two carrier component carrier aggregation combinations
Target Market
The LE915Ax-P family is specifically designed to enable cellular data connectivity on
CBRS networks operating on LTE band 48 in US. It can also operate on other networks
operating on LTE band 42 and 43.
It also meets the requirements for M2M application such as metering, tracking system,
security solutions, routers, wireless POS, among others.

LE915Ax-P Hardware Design Guide
1VV0301680 Rev. 2 Page 9of 51 2021-10-04
Not Subject to NDA
Main Features
Main features of the LE915Ax-P are listed below.
Feature
Description
Physical
LCC (32 x 29 x2.4mm),
134 pads carrying useful signals
Power supply
Nominal 3.8V single power supply
Operating voltage
recommended
-30 ~ +60 °C ambient
Serial interface
USB 2.0, 1 High Speed UART with HW flow control and 2 Low Speed UARTs w/o flow
control
Cellular technology
LE915A6-P: LTE CAT.6, TDD, 200Mbps on DL, 3GPP release 10
LE915A4-P: LTE CAT.4, TDD, 100Mbps on DL, 3GPP release 9
Diversity/2nd RX
4G: all operating on all supported frequency bands
SIM interface
Single interface for 1.8V and 3.0V
Antenna ports
1 main and 1 auxiliary antenna ports
Table 4: LE915Ax-P Feature Summary
TX Output Power
LTE/CBRS Band
Conducted power (dBm) @BW 5MHz, Full RB
42
23 +1/-1.7
43
23 +1/-1.7
48
22 +1/-1.7
Table 5: Transmission Output Power
RX Sensitivity
LTE/CBRS Band
Typical sensitivity (dBm) @BW 5MHz
42
<-101
43
<-101
48
<-101
Table 6: Reception Sensitivity

LE915Ax-P Hardware Design Guide
1VV0301680 Rev. 2 Page 10 of 51 2021-10-04
Not Subject to NDA
Mechanical Specifications
2.7.1. Dimensions and LCC Pads Layout
The overall dimensions of LE915Ax-P family are:
•Length: 32 mm
•Width: 29 mm
•Thickness: 2.4 mm
2.7.2. Weight
The nominal weight of the LE915Ax-P family is 5.1 grams.
Temperature Range
Tempeurature Range
Note
Recommended Operating Temperature
Range (3GPP compliant)
–30°C to +60°C
The module is fully functional and compliant
according to regulatory standards.
Storage Temperature Range
–40°C to +85°C
The module is not powered and not connected
to power supply
Table 7: Temperature Range

LE915Ax-P Hardware Design Guide
1VV0301680 Rev. 2 Page 11 of 51 2021-10-04
Not Subject to NDA
3. PINS ALLOCATION
Pin-out
Pin
Signal
I/O
Function
Type
Comment
USB HS 2.0 COMMUNICATION PORT
57
USB_D+
I/O
USB differential Data (+)
3.3V
58
USB_D-
I/O
USB differential Data (-)
3.3V
56
USB_EXT_VBUS_VLD
I
USB port detection
1.8V
Asynchronous Serial Ports
25
UART2_SIN
I
Serial data input from DTE
1.8V
UART2
26
UART2_SOUT
O
Serial data output to DTE
1.8V
UART2
23
UART2_CTS
I
Input for Clear to Send from DTE
1.8V
UART2
24
UART2_RTS
O
Output for Request to Send to DTE
1.8V
UART2
21
UART0_SIN
I
Serial data input from DTE
1.8V
UART0
22
UART0_SOUT
O
Serial data output to DTE
1.8V
UART0
119
UART1_SIN
I
Serial data input from DTE
1.8V
UART1
131
UART1_SOUT
O
Serial data output to DTE
1.8V
UART1
SIM Card Interface
68
SIMCLK
O
External SIM signal –Clock
1.8V
66
SIMRST
O
External SIM signal –Reset
1.8V
67
SIMIO
I/O
External SIM signal –Data I/O
1.8V
69
SIMIN
I
External SIM signal –Presence
1.8V
65
SIMVCC
PO
External SIM signal –Power supply for the SIM
1.8V
DIGITAL IO
16
GPIO_1
I/O
GPIO_1
1.8V
30
GPIO_2
I/O
GPIO_2
1.8V
71
GPIO_3
I/O
GPIO_3
1.8V
72
GPIO_4
I/O
GPIO_4
1.8V
73
GPIO_5
I/O
GPIO_5
1.8V
RF SECTION
4
ANT_MAIN
I
Main LTE Antenna port (50 ohm)
RF
2
ANT_DIV
I
Secondary LTE Antenna port (50 ohm)
RF

LE915Ax-P Hardware Design Guide
1VV0301680 Rev. 2 Page 12 of 51 2021-10-04
Not Subject to NDA
Pin
Signal
I/O
Function
Type
Comment
Miscellaneous Functions
64
MODULE_PWR_EN
I
Module power ON/OFF control
1.8V
63
RESET_N
I
Reset control
1.8V
Active low
18
NETWORK_LED
O
Downlink status indication LED
7
HWID1
I
Reserved
1.8V
6
HWID2
I
Reserved
1.8V
80
FFF_FFH
I
Reserved
1.8V
J-TAG
120
TRST_N
I
Reserved, JTAG for debugging
121
TMS
I
Reserved, JTAG for debugging
122
TDI
I
Reserved, JTAG for debugging
133
TCK
I
Reserved, JTAG for debugging
134
TDO
O
Reserved, JTAG for debugging
Power Supply
59
VBAT1
-
Main power supply (Baseband), 3.8V nominal
Power
60
VBAT1
-
Main power supply (Baseband), 3.8V nominal
Power
11
VBAT2
-
Main power supply (Radio PA) , 3.8V nominal
Power
12
VBAT2
-
Main power supply (Radio PA) , 3.8V nominal
Power
62
1V8_D
-
1.8V output
Power
1
GND
-
Ground
Power
3
GND
-
Ground
Power
5
GND
-
Ground
Power
10
GND
-
Ground
Power
13
GND
-
Ground
Power
29
GND
-
Ground
Power
61
GND
-
Ground
Power
81
GND
-
Ground
Power
82
GND
-
Ground
Power
83
GND
-
Ground
Power
84
GND
-
Ground
Power
85
GND
-
Ground
Power
86
GND
-
Ground
Power

LE915Ax-P Hardware Design Guide
1VV0301680 Rev. 2 Page 13 of 51 2021-10-04
Not Subject to NDA
Pin
Signal
I/O
Function
Type
Comment
87
GND
-
Ground
Power
88
GND
-
Ground
Power
89
GND
-
Ground
Power
90
GND
-
Ground
Power
91
GND
-
Ground
Power
92
GND
-
Ground
Power
93
GND
-
Ground
Power
94
GND
-
Ground
Power
95
GND
-
Ground
Power
96
GND
-
Ground
Power
97
GND
-
Ground
Power
98
GND
-
Ground
Power
99
GND
-
Ground
Power
100
GND
-
Ground
Power
101
GND
-
Ground
Power
102
GND
-
Ground
Power
103
GND
-
Ground
Power
104
GND
-
Ground
Power
105
GND
-
Ground
Power
106
GND
-
Ground
Power
107
GND
-
Ground
Power
108
GND
-
Ground
Power
109
GND
-
Ground
Power
110
GND
-
Ground
Power
DNC (Do Not Connect)
111
DNC
-
112
DNC
-
113
DNC
-
114
DNC
-
115
DNC
-
116
DNC
-
117
DNC
-

LE915Ax-P Hardware Design Guide
1VV0301680 Rev. 2 Page 14 of 51 2021-10-04
Not Subject to NDA
Pin
Signal
I/O
Function
Type
Comment
118
DNC
-
123
DNC
-
124
DNC
-
125
DNC
-
126
DNC
-
127
DNC
-
128
DNC
-
129
DNC
-
130
DNC
-
132
DNC
-
RESERVED
8
RESERVED
-
RESERVED
9
RESERVED
-
RESERVED
14
RESERVED
-
RESERVED
15
RESERVED
-
RESERVED
16
RESERVED
-
RESERVED
17
RESERVED
-
RESERVED
19
RESERVED
-
RESERVED
20
RESERVED
-
RESERVED
27
RESERVED
-
RESERVED
28
RESERVED
-
RESERVED
30
RESERVED
-
RESERVED
31
RESERVED
-
RESERVED
32
RESERVED
-
RESERVED
33
RESERVED
-
RESERVED
34
RESERVED
-
RESERVED
35
RESERVED
-
RESERVED
36
RESERVED
-
RESERVED
37
RESERVED
-
RESERVED
38
RESERVED
-
RESERVED
39
RESERVED
-
RESERVED
40
RESERVED
-
RESERVED

LE915Ax-P Hardware Design Guide
1VV0301680 Rev. 2 Page 15 of 51 2021-10-04
Not Subject to NDA
Pin
Signal
I/O
Function
Type
Comment
41
RESERVED
-
RESERVED
42
RESERVED
-
RESERVED
43
RESERVED
-
RESERVED
44
RESERVED
-
RESERVED
45
RESERVED
-
RESERVED
46
RESERVED
-
RESERVED
47
RESERVED
-
RESERVED
48
RESERVED
-
RESERVED
49
RESERVED
-
RESERVED
50
RESERVED
-
RESERVED
51
RESERVED
-
RESERVED
52
RESERVED
-
RESERVED
53
RESERVED
-
RESERVED
54
RESERVED
-
RESERVED
55
RESERVED
-
RESERVED
70
RESERVED
-
RESERVED
71
RESERVED
-
RESERVED
72
RESERVED
-
RESERVED
73
RESERVED
-
RESERVED
74
RESERVED
-
RESERVED
75
RESERVED
-
RESERVED
76
RESERVED
-
RESERVED
77
RESERVED
-
RESERVED
78
RESERVED
-
RESERVED
79
RESERVED
-
RESERVED
Table 8: Pin-out Information

LE915Ax-P Hardware Design Guide
1VV0301680 Rev. 2 Page 16 of 51 2021-10-04
Not Subject to NDA
4. POWER SUPPLY
The power supply circuitry and the board layout are a very important part in the full
product design and they strongly reflect on the product overall performances, so the
requirements and the guidelines that will follow should be read carefully for a proper
design.
Main Power Supply Requirements
The external power supply must be connected to VBAT1 and VBAT2 pads and must fulfil
the following requirements:
Power Supply
Value
Recommended Nominal Supply Voltage
3.8V
Operating Voltage Range
3.3 V - 4.4 V
Maximum ripple on module input supply
30mV
Table 9: Power Supply Requirements
The minimum operating voltage acceptable for LE915Ax-P is 3,3 V. Special care must be
taken to prevent voltage drops below 3.3V even when transmission starts from idle state.
It is highly recommended to apply a voltage monitoring circuit in the application board to
ensure that the supply voltage is suitable for stable operating.
Note: The power supply should be dimensioned for at least 2.0A at
nominal power supply voltage.
Power Consumption (Typical)
Table 10: Power consumption
Test condition
LE915A6-P (mA)
LE914-P (mA)
Off current
0.7
0.6
Idle current (128 cycle)
427
346
Idle current (256 cycle)
427
346
LTE (TX = 0dBm)
1050
670
LTE (TX = 23dBm)
1410
1010

LE915Ax-P Hardware Design Guide
1VV0301680 Rev. 2 Page 17 of 51 2021-10-04
Not Subject to NDA
1.8V Power Output
The pad, 1V8_D, is a reference voltage output for IOs. It can be used to provide 1.8V power
to small devices up to 50mA max.
Table 11: 1.8V power output
General Design Rule
The main guidelines for the Power Supply Design include three different design steps:
•the electrical design of the power supply
•the thermal design
•the PCB layout
4.4.1. Electrical Design Guidelines
The electrical design of the power supply strongly depends on the power source where
this power is drained.
4.4.1.1. +5V Source Power Supply Design Guidelines
•The desired output for the power supply is 3.8V, so there's not a big difference
between the input source and the desired output and a linear regulator can be
used. A switching power supply will not be suitable due to the low drop out
requirements.
•When using a linear regulator, a proper heat sink shall be provided in order to
dissipate the power generated.
•A Bypass low ESR capacitor of adequate capacity must be provided in order to cut
the current absorption peaks close to the Module, a 100μF capacitor is usually
suitable.
•Make sure the low ESR capacitor on the power supply output rated at least 10V.
•A protection diode must be inserted close to the power input to protect Telit
module from power polarity inversion and/or EOS.
Pin
Signal
I/O
Min (V)
Typical (V)
Max (V)
62
1V8_D
-
1.71
1.8
1.89

LE915Ax-P Hardware Design Guide
1VV0301680 Rev. 2 Page 18 of 51 2021-10-04
Not Subject to NDA
Figure 1: An Example of Linear Regulator with 5V Input
4.4.2. Thermal Design Guidelines
Thermal dispersion needs to be carefully considered in entire customer device design.
The power supply heat sink must be dimensioned according to the following guidelines:
•Opening a large ground plane as wider as Telit module size and to add a thermal
interface material tightly touched between the bottom side of Telit module and the
customer board is a mandatory.
•Adding a heat sink on top of the shield cover with a thermal interface material and
making an air flow mechanism for cooling down the heat is also highly
recommended.
•Applying a cooling down system in the customer application design is much better
as an option.
The body of the Telit module must be connected to the ground plane and/or metal chassis
of the host board for better radio performance and thermal dissipation.
4.4.3. Power Supply PCB Layout Guidelines
As seen in the for electrical design guidelines, to protect the supply from spikes, the
power supply shall have a low ESR capacitor on the output to cut the current peaks on
the input. The placement of this component is essential for the correct functioning of the
circuitry. A misplaced component can be useless or even decrease the performance of
the power supply..

LE915Ax-P Hardware Design Guide
1VV0301680 Rev. 2 Page 19 of 51 2021-10-04
Not Subject to NDA
•The Bypass low ESR capacitor must be placed close to the power input pads or, in
the case the power supply is of a switching type it can be placed close to the
inductor to cut the ripple, provided the PCB trace from the capacitor to Telit
module is wide enough to ensure a voltage dropless connection.
•The protection diode must be placed close to the input connector where the power
source is drained.
•The PCB traces from the input connector to the power regulator IC must be wide
enough to ensure that no voltage drops occurs.
•The PCB traces to Telit module and the Bypass capacitor must be wide enough to
ensure that no significant voltage drops occurs. This is for the same reason as
previous point. Try to keep this trace as short as possible.
•To reduce the EMI due to switching, it is important to keep the mesh involved very
small; therefore the input capacitor, the output diode (if not embodied in the IC)
and the regulator, must form a very small loop.This is done in order to reduce the
radiated field (noise) at the switching frequency (100-500 kHz usually).
•A dedicated ground for the Switching regulator separated by the common ground
plane is suggested.
•The placement of the power supply on the board should be done in such a way to
guarantee that the high current return paths in the ground plane are not
overlapped to any noise sensitive circuitry, as the microphone amplifier/buffer or
earphone amplifier.
•The power supply input cables should be kept separate from noise sensitive lines
such as microphone/earphone cables.
•The insertion of EMI filter on power supply pins is recommended in those designs
where antenna is placed close to the power supply lines. For this purpose a ferrite
bead like Murata BLM18EG101TN1 or Taiyo Yuden P/N FBMH1608HM101 can be
used.
The below figure shows the recommended circuit:

LE915Ax-P Hardware Design Guide
1VV0301680 Rev. 2 Page 20 of 51 2021-10-04
Not Subject to NDA
Figure 2: Recommended Circuit of EMI filter