Sierra Wireless AR7552 Cellular/PCS WCDMA/LTE Modem User Manual Hardware Integration Guide
Sierra Wireless Inc. Cellular/PCS WCDMA/LTE Modem Hardware Integration Guide
AirPrime - AR7552 - Hardware Integration Guide - Rev1.0_v7
4117336
Rev 1.0
May 18, 2015
AirPrime AR7552
Hardware Integration Guide
4117336 Rev 1.0 May 18, 2015 2
Hardware Integration Guide
Important Notice
Due to the nature of wireless communications, transmission and reception of data can never be
guaranteed. Data may be delayed, corrupted (i.e., have errors) or be totally lost. Although significant
delays or losses of data are rare when wireless devices such as the Sierra Wireless modem are used
in a normal manner with a well-constructed network, the Sierra Wireless modem should not be used
in situations where failure to transmit or receive data could result in damage of any kind to the user or
any other party, including but not limited to personal injury, death, or loss of property. Sierra Wireless
accepts no responsibility for damages of any kind resulting from delays or errors in data transmitted or
received using the Sierra Wireless modem, or for failure of the Sierra Wireless modem to transmit or
receive such data.
Safety and Hazards
Do not operate the Sierra Wireless modem in areas where cellular modems are not advised without
proper device certifications. These areas include environments where cellular radio can interfere such
as explosive atmospheres, medical equipment, or any other equipment which may be susceptible to
any form of radio interference. The Sierra Wireless modem can transmit signals that could interfere
with this equipment. Do not operate the Sierra Wireless modem in any aircraft, whether the aircraft is
on the ground or in flight. In aircraft, the Sierra Wireless modem MUST BE POWERED OFF. When
operating, the Sierra Wireless modem can transmit signals that could interfere with various onboard
systems.
Note: Some airlines may permit the use of cellular phones while the aircraft is on the ground and the door
is open. Sierra Wireless modems may be used at this time.
The driver or operator of any vehicle should not operate the Sierra Wireless modem while in control of
a vehicle. Doing so will detract from the driver or operator’s control and operation of that vehicle. In
some states and provinces, operating such communications devices while in control of a vehicle is an
offence.
Limitations of Liability
This manual is provided “as is”. Sierra Wireless makes no warranties of any kind, either expressed or
implied, including any implied warranties of merchantability, fitness for a particular purpose, or
noninfringement. The recipient of the manual shall endorse all risks arising from its use.
The information in this manual is subject to change without notice and does not represent a
commitment on the part of Sierra Wireless. SIERRA WIRELESS AND ITS AFFILIATES
SPECIFICALLY DISCLAIM LIABILITY FOR ANY AND ALL DIRECT, INDIRECT, SPECIAL,
GENERAL, INCIDENTAL, CONSEQUENTIAL, PUNITIVE OR EXEMPLARY DAMAGES INCLUDING,
BUT NOT LIMITED TO, LOSS OF PROFITS OR REVENUE OR ANTICIPATED PROFITS OR
REVENUE ARISING OUT OF THE USE OR INABILITY TO USE ANY SIERRA WIRELESS
PRODUCT, EVEN IF SIERRA WIRELESS AND/OR ITS AFFILIATES HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES OR THEY ARE FORESEEABLE OR FOR CLAIMS BY ANY
THIRD PARTY.
Notwithstanding the foregoing, in no event shall Sierra Wireless and/or its affiliates aggregate liability
arising under or in connection with the Sierra Wireless product, regardless of the number of events,
occurrences, or claims giving rise to liability, be in excess of the price paid by the purchaser for the
Sierra Wireless product.
Customer understands that Sierra Wireless is not providing cellular or GPS (including A-GPS)
services. These services are provided by a third party and should be purchased directly by the
Customer.
4117336 Rev 1.0 May 18, 2015 3
Hardware Integration Guide
SPECIFIC DISCLAIMERS OF LIABILITY: CUSTOMER RECOGNIZES AND ACKNOWLEDGES
SIERRA WIRELESS IS NOT RESPONSIBLE FOR AND SHALL NOT BE HELD LIABLE FOR ANY
DEFECT OR DEFICIENCY OF ANY KIND OF CELLULAR OR GPS (INCLUDING A-GPS)
SERVICES.
Patents
This product may contain technology developed by or for Sierra Wireless Inc.
This product includes technology licensed from QUALCOMM®.
This product is manufactured or sold by Sierra Wireless Inc. or its affiliates under one or more patents
licensed from InterDigital Group and MMP Portfolio Licensing.
Copyright
© 2015 Sierra Wireless. All rights reserved.
Trademarks
Sierra Wireless®, AirPrime®, AirLink®, AirVantage®, WISMO® and the Sierra Wireless and Open AT
logos are registered trademarks of Sierra Wireless, Inc. or one of its subsidiaries.
Watcher® is a registered trademark of Netgear, Inc., used under license.
Windows® and Windows Vista® are registered trademarks of Microsoft Corporation.
Macintosh® and Mac OS X® are registered trademarks of Apple Inc., registered in the U.S. and other
countries.
QUALCOMM® is a registered trademark of QUALCOMM Incorporated. Used under license.
Other trademarks are the property of their respective owners.
Contact Information
Sales Desk:
Phone:
1-604-232-1488
Hours:
8:00 AM to 5:00 PM Pacific Time
Contact:
http://www.sierrawireless.com/sales
Post:
Sierra Wireless
13811 Wireless Way
Richmond, BC
Canada V6V 3A4
Technical Support:
support@sierrawireless.com
RMA Support:
repairs@sierrawireless.com
Fax:
1-604-231-1109
Web:
http://www.sierrawireless.com/
Consult our website for up-to-date product descriptions, documentation, application notes, firmware
upgrades, troubleshooting tips, and press releases: www.sierrawireless.com
4117336 Rev 1.0 May 18, 2015 4
Hardware Integration Guide
Document History
Version
Date
Updates
1.0
May 18, 2015
Creation based on document 4116922: AirPrime - AR7558 - Hardware
Integration Guide - Rev1.0.
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Contents
1. INTRODUCTION .................................................................................................. 7
1.1. General Features ............................................................................................................... 7
2. POWER INTERFACE ........................................................................................... 8
2.1. Power Supply .................................................................................................................... 8
2.2. Absolute Maximum and ESD Ratings ............................................................................... 8
2.3. Power and Ground Recommendations ............................................................................. 9
3. RF SPECIFICATION .......................................................................................... 10
3.1. LTE RF Interface ............................................................................................................. 10
3.1.1. LTE Max TX Output Power ...................................................................................... 10
3.1.2. LTE RX Sensitivity ................................................................................................... 10
3.2. WCDMA RF Interface ...................................................................................................... 11
3.2.1. WCDMA Max TX Output Power ............................................................................... 11
3.2.2. WCDMA RX Sensitivity ............................................................................................ 11
3.3. WWAN Antenna Interface ............................................................................................... 12
3.3.1. WWAN Antenna Recommendations ........................................................................ 12
3.4. Primary Antenna Diagnostics .......................................................................................... 13
3.5. RX2 Antenna Diagnostics ............................................................................................... 13
4. AUDIO ................................................................................................................ 15
4.1. Analog Audio ................................................................................................................... 15
4.2. Digital Audio .................................................................................................................... 16
5. ROUTING CONSTRAINTS AND RECOMMENDATIONS ................................. 17
5.1. RF Routing Recommendations ....................................................................................... 17
5.2. Power and Ground Recommendations ........................................................................... 19
5.3. Antenna Recommendations ............................................................................................ 19
5.4. Interface Circuit Recommendations ................................................................................ 20
6. REGULATORY INFORMATION ......................................................................... 22
6.1. Important Notice .............................................................................................................. 22
6.2. Safety and Hazards ......................................................................................................... 22
6.3. Important Compliance Information for USA OEM Integrators ......................................... 22
7. REFERENCES ................................................................................................... 24
7.1. Reference Documents ..................................................................................................... 24
7.2. Abbreviations ................................................................................................................... 24
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List of Tables
Table 1. AirPrime AR7552 Embedded Module ............................................................................... 7
Table 2. Power Supply Requirements ............................................................................................. 8
Table 3. Power Supply Pads ........................................................................................................... 8
Table 4. AirPrime AR7552 Absolute Maximum Ratings .................................................................. 8
Table 5. Conducted TX (Transmit) Max output Power Tolerances – LTE Bands ......................... 10
Table 6. Conducted RX Sensitivity 3GPP (BW: 10MHz) – LTE Bands (Note 1, 4) ...................... 11
Table 7. AirPrime AR7552 Maximum WCDMA Transmitter Output Power .................................. 11
Table 8. AirPrime AR7552 Minimum WCDMA Receiver Sensitivity ............................................. 11
Table 9. AirPrime AR7552 WWAN Antenna Characteristics ........................................................ 12
Table 10. WWAN Antenna Interface Pads ...................................................................................... 12
Table 11. AirPrime AR7552 WWAN Antenna Recommendations ................................................. 12
Table 12. Primary Antenna ADC Characteristics ............................................................................ 13
Table 13. Primary Antenna Diagnostics Ranges ............................................................................ 13
Table 14. RX2 Antenna ADC Characteristics.................................................................................. 13
Table 15. RX2 Antenna Diagnostics Ranges .................................................................................. 14
Table 16. Analog Audio Interface Pads ........................................................................................... 15
Table 17. Analog Audio Interface Characteristics ........................................................................... 15
Table 18. Digital Audio Interface Pads ............................................................................................ 16
Table 19. The specification of RF Trace of The CCB, Main Port .................................................... 21
Table 20. The specification of RF Trace of The CCB, Diversity and GPS Port ............................. 21
Table 21. Reference Specifications ................................................................................................. 24
Table 22. Abbreviations ................................................................................................................... 24
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1. Introduction
1.1. General Features
The AirPrime AR7552 embedded modules are designed for the automotive industry. They support
LTE, WCDMA air interface standards and shares hardware and firmware interfaces with the AirPrime
AR5550 and AR855x. They also have Global Navigation Satellite System (GNSS) capabilities
including GPS and GLONASS.
The AirPrime AR7552 embedded modules are based on the Qualcomm MDM9615 wireless chipset
and support the following bands.
Table 1. AirPrime AR7552 Embedded Module
Product
Description
Band Support
AirPrime
AR7552
LTE/WCDMA embedded module
LTE: B2, B4, B5, B7, B17
WCDMA: B2, B5
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2. Power Interface
2.1. Power Supply
The AirPrime AR7552 embedded module is powered via a single regulated DC power supply, 3.7V
nominal. The power supply requirements can be found in the following table.
Table 2. Power Supply Requirements
Power Supply
Min
Typ
Max
Units
Main DC Power Input Range
3.4
3.7
4.2
V
Power Supply Ripple
0 to 1kHz
-
-
200
mVpp
>1kHz
-
-
50
mVpp
Maximum Current draw
AR7552
-
-
tbd
mA
AirPrime AR7552 does not support USB bus-powered operation. DC power must be supplied via the
VBATT input.
Table 3. Power Supply Pads
Pad
Name
Direction
Function
If Unused
EA2
VBATT
Input
Power Supply Input
Must Be Used
EB2
VBATT
Input
Power Supply Input
Must Be Used
EC2
VBATT
Input
Power Supply Input
Must Be Used
2.2. Absolute Maximum and ESD Ratings
This section defines the Absolute Maximum and Electrostatic Discharge (ESD) Ratings of the
AirPrime AR7552 embedded modules.
Warning: If these parameters are exceeded, even momentarily, damage may occur to the device.
Table 4. AirPrime AR7552 Absolute Maximum Ratings
Parameter
Min
Max
Units
VBATT
Power Supply Input
-
5.0
V
VIN
Voltage on any digital input or output pin
-
VCC_1v8+0.5
V
IIN
Latch-up current
-100
100
mA
Maximum Voltage applied to antenna interface pins
VANT
Primary Antenna
-
36
V
RX2 Antenna
-
36
V
GNSS Antenna
-
36
V
ESD Ratings
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Power Interface
Parameter
Min
Max
Units
ESD1
Primary, RX2 and GNSS antenna pads - Contact
-
± 8
kV
All other signal pads - Contact
-
± 1.5
kV
1 The ESD Simulator configured with 330pF, 1000Ω.
Caution: The AirPrime AR7552 embedded modules are sensitive to Electrostatic Discharge. ESD
countermeasures and handling methods must be used when handling the AirPrime AR7552
devices.
2.3. Power and Ground Recommendations
Power and ground routing is critical to achieving optimal performance of the AirPrime AR7552 devices
when integrated into an application.
Recommendations:
Do not use a separate GND for the Antennas
Connections to GND from the AirPrime AR7552 should be flooded plane using thermal reliefs
to ensure reliable solder joints.
VBATT is recommended to be routed as a wide trace(s) directly from the 4V supply to the
LGA pad.
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3. RF Specification
This section presents the WWAN RF interface of the AirPrime AR7552 series of embedded modules.
The specifications for the LTE, CDMA and WCDMA interfaces are defined.
3.1. LTE RF Interface
This section presents the LTE RF Specification for the AirPrime AR7552.
3.1.1. LTE Max TX Output Power
The Maximum Transmitter Output Power of the AirPrime AR7552 embedded modules are specified in
the following table.
Table 5. Conducted TX (Transmit) Max output Power Tolerances – LTE Bands
Band
Standard (dBm)
(Note 2)
Class A (dBm) (Note 3)
Notes
B2
23 ±2.7dB
23 ±2.0dB
Note 1,4
B4
23 ±2.7dB
23 ±2.0dB
Note 1
B5
23 ±2.7dB
23 ±2.0dB
Note 1
B7
23 ±2.7dB
22.5 +3.2/-1.7dB
Note 1,4
B17
23 ±2.7dB
23 ±2.0dB
Note 1
Note 1: The test configurations for all of the entries in the table above are per 3GPP specification, Connectorized (Class
3).
Note 2: Per 3GPP TS 36.521-1 6.2.2 UE Maximum Output Power ( No MPR);and for B13,Per VzW's
Supplementary_RF_Conformance. 2.1 Maximum Output Power – No MPR Or A-MPR
Note 3: Class A is defined in 3.3 Environmental
Note 4: For transmission bandwidths (Figure 5.4.2-1) confined within FUL_low and FUL_low + 4 MHz or FUL_high – 4
MHz and FUL_high, the maximum output power requirement is relaxed by reducing the lower tolerance limit by 1.5 dB.
3.1.2. LTE RX Sensitivity
The Minimum Receiver Sensitivity of the AirPrime AR7552 embedded modules are specified in the
following table.
Note: For the table below:
Dual receiver (SIMO) per 3GPP TS 36.521-1 Rx Sensitivity Specification.
Sensitivity values scale with bandwidth:
x_MHz_Sensitivity = 10 MHz_Sensitivity - 10*log(10 MHz/x_MHz)
10 MHz BW,and 50 RB DownLink and Up Link as 3GPP TS 36.521-1 Table 7.3.5-2.
All values are preliminary pending transceiver matching and testing.
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RF Specification
Table 6. Conducted RX Sensitivity 3GPP (BW: 10MHz) – LTE Bands (Note 1, 4)
Band
Standard (dBm)
(Note 2)
Room Typical
(dBm)
Class A (Extreme)
Typical (dBm)
(Note 5)
Class A Limit (
dBm) (Note 5)
B2
-94.3
-101
-100
-95.5
B4
-96.3
-101.5
-101
-97
B5
-94.3
-102.5
-102
-95.5
B7
-94.3
-100
-99
-95.5
B17
-93.3
-102
-101
-94.5
Note 1: Dual receiver (SIMO) Per 3GPP TS 36.521-1 Rx Sensitivity Specification.
Note 2: Per 3GPP Specification.
Note 3:Sensitivity values scale with bandwidth: x_MHz_Sensitivity = 10 MHz_Sensitivity - 10*log(10 MHz/x_MHz)
Note 4: 10 MHz BW,and 50 RB DownLink and Up Link as 3GPP TS 36.521-1 Table 7.3.5-2.
Note 5: Class A is defined in 3.3 Environmental
Note 6: The requirement is modified by -0.5 dB when the carrier frequency of the assigned E-UTRA channel bandwidth is
within 865-894 MHz.
3.2. WCDMA RF Interface
This section presents the WCDMA RF Specification for the AirPrime AirPrime AR7552 embedded
modules.
3.2.1. WCDMA Max TX Output Power
The Maximum Transmitter Output Power of the AirPrime AR7552 embedded module are specified in
the following table.
Table 7. AirPrime AR7552 Maximum WCDMA Transmitter Output Power
Band
Frequency Band
Nominal Max TX Output
Power
Tolerance
II (1900/PCS)
1850 MHz to 1910 MHz
+23.5 dBm
+2.2/-2.7 dB
V (850/CELL)
824 MHz to 849 MHz
3.2.2. WCDMA RX Sensitivity
The Minimum Receiver Sensitivity of the AirPrime AR7552 embedded module are specified in the
following table.
Table 8. AirPrime AR7552 Minimum WCDMA Receiver Sensitivity
Band
Frequency Band
Minimum RX Downlink
Criteria
II (1900/PCS)
1930 MHz to 1990 MHz
-106 dBm (Class A)
-105 dBm (Class B)
BER < 0.001
V (850/CELL)
869 MHz to 894 MHz
-107 dBm (Class A)
-106 dBm (Class B)
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RF Specification
3.3. WWAN Antenna Interface
The specification for the WWAN Antenna Interface of the AirPrime AR7552 embedded modules are
defined in the table below.
Table 9. AirPrime AR7552 WWAN Antenna Characteristics
Characteristics
WCDMA B5
LTE B5
WCDMA B2
LTE B2
LTE B4
LTE B7
LTE B17
Frequency (MHz)
TX
824-849
1850-1910
1710 – 1755
2500-2570
704 – 716
RX
869-894
1930-1990
2110 – 2155
2620-2690
734– 746
Impedance
RF
50 Ω
VSWR max
RX
2:1
TX
2:1
Maximum Voltage
Primary Antenna – 36 Volts
RX2 Antenna – 36 Volts (LTE MIMO: tbd)
Note: RX2 Antenna port is RX only, RX parameters in the above tables are also applicable.
Table 10. WWAN Antenna Interface Pads
Pad
Name
Direction
Function
BA11
GND
Primary Antenna Ground
BA12
PRIMARY_ANT
Input/Output
Primary Antenna Interface
BA13
GND
Primary Antenna Ground
BA7
GND
Diversity Antenna Ground
BA8
DIVERSITY_ANT
Input
Diversity Antenna Interface
BA9
GND
Diversity Antenna Ground
3.3.1. WWAN Antenna Recommendations
The table below defines the key characteristics to consider for antenna selection.
Table 11. AirPrime AR7552 WWAN Antenna Recommendations
Characteristics
WCDMA B5
LTE B5
WCDMA B2
LTE B2
LTE B4
LTE B7
LTE B17
Frequency (MHz)
TX
824-849
1850-1910
1710 – 1755
2500-2570
704 – 716
RX
869-894
1930-1990
2110 – 2155
2620-2690
734– 746
Impedance
RF
50 Ω
DC
10 kΩ ±1k
VSWR max
RX
1.5: 1
TX
1.5: 1
Polarization
Linear, vertical
Typical radiated gain
0 dBi in one direction at least
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RF Specification
3.4. Primary Antenna Diagnostics
The primary antenna diagnostic feature allows the AirPrime AR7552 embedded module to determine
if the primary antenna connected to the module is: open, shorted or normal. The antenna connected
to this interface needs to have a DC resistance to ground of 10 kΩ ± 1k embedded inside.
The ARx55x FW accepts two limits which are used to evaluate the status of the antenna, representing
the short and open thresholds. Refer to document [7] for the syntax of AT+ANTLIMT.
Table 12. Primary Antenna ADC Characteristics
Min
Nom
Max
Units
ADC Voltage Range
0
0.9
1.8
Volts
Resolution
-
15
Bit
ADC Values
0
16383
Voltage/ADC step
~0.0011
Volts
1 Assumes 10kΩ Nominal DC resistance in the attached antenna and internal to AirPrime AR7552 device
The following example illustrates the Antenna states and resistance values for a typical limit setting.
AT+ANTLIMT=1,839,1088
Table 13. Primary Antenna Diagnostics Ranges
Antenna State
Min ADC
Max ADC
Antenna Resistance Range
Short
0
839
~ ≤ 7 kΩ
Normal
841
1086
7 kΩ < x < 13 kΩ
Open
1088
1900
≥ 13 kΩ
Note: Highlighted numbers in the table above are programmed as shortLim and openLim using the
+ANTLIMT command.
3.5. RX2 Antenna Diagnostics
The RX2 antenna diagnostic feature allows the AirPrime AR75520 to determine if the RX2 antenna
connected to the module is: open, shorted or normal. The antenna connected to this interface needs
to have a DC resistance to ground of 10 kΩ ± 1k embedded inside.
The AirPrime AR7552 FW accepts two limits which are used to evaluate the status of the antenna,
representing the short and open thresholds. Refer to document [7] for the syntax of AT+ANTLIMT.
Table 14. RX2 Antenna ADC Characteristics
Min
Nom
Max
Units
ADC Voltage Range
0
0.9
1.8
Volts
Resolution
-
15
Bit
ADC Values
0
16383
Voltage/ADC step
~0.0011
Volts
1 Assumes 10kΩ Nominal DC resistance in the attached antenna and internal to AirPrime AR7552 device
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RF Specification
The following example illustrates the Antenna states and resistance values for a typical limit setting.
AT+ANTLIMT=2,839,1088
Table 15. RX2 Antenna Diagnostics Ranges
Antenna State
Min ADC
Max ADC
Antenna Resistance Range
Short
0
839
~ ≤ 7 kΩ
Normal
841
1086
7 kΩ < x < 13 kΩ
Open
1088
1900
≥ 13 kΩ
Note: Highlighted numbers in the table above are programmed as shortLim and openLim using the
+ANTLIMT command.
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4. Audio
The AirPrime AR7552 supports both Analog and Digital audio interfaces. The following diagram
illustrates the Audio subsystem and identifies where various AT commands affect the audio
subsystem. Refer to document [7] for details of the AT commands.
4.1. Analog Audio
The AirPrime AR7552 provides a mono differential analog audio interface.
Table 16. Analog Audio Interface Pads
Pad
Name
Direction
Function
Interface
CD9
AUDIO1_IN_P
Input
Microphone 1 input positive
Primary
CC10
AUDIO1_IN_M
Microphone 1 input negative
CE6
AUDIO1_OUT_P
Output
Speaker 1 output positive
CE8
AUDIO1_OUT_M
Speaker 1 output negative
Table 17. Analog Audio Interface Characteristics
Analog Audio
Min.
Typ.
Max.
Units
Audio IN
Input Impedance
16
20
24
kΩ
Signal Level – Differential
-0.3
-
2.9
dBV
Signal Level – Single-ended
(the unused audio signal must be tied to
GND or analog reference)
-0.3
-
2.9
dBV
Audio OUT
Signal Level – Differential
-
-
dBV
Signal Level – Single-ended
-0.3
-
2.9
dBV
Output Impedance
-0.3
-
2.9
Ω
Signal Drive Strength – Application Load
-
600
1M
kΩ
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Audio
4.2. Digital Audio
The AirPrime AR7552 provides a 4-wire digital audio interface. This interface can be configured as
either a PCM or an I2S.
Table 18. Digital Audio Interface Pads
Pad
Name
Direction1
PCM
Function
Direction
I2S Function
If Unused
DB3
PCM_FS
Output
PCM Frame
Sync
Input/Output
I2S_WS
Leave Open
DA3
PCM_CLK
Output
PCM Clock
Input/Output
I2S_SCLK
Leave Open
DC2
PCM_DOUT
Output
PCM Data Out
Output
I2S_DOUT
Leave Open
DD2
PCM_DIN
Input
PCM Data In
Input
I2S_DIN
Leave Open
1 Direction when defined in Master mode.
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5. Routing Constraints and
Recommendations
Layout and routing of the AirPrime AR7552 device in the application is critical to maintaining the
performance of the radio. The following sections provide guidance to the developer when designing
their application to include an AirPrime AR7552 device and achieve optimal system performance.
5.1. RF Routing Recommendations
To route the RF antenna signals, the following recommendations must be observed for PCB layout:
The RF signals must be routed using traces with a 50 characteristic impedance.
Basically, the characteristic impedance depends on the dielectric constant (εr) of the material used,
trace width (W), trace thickness (T), and height (H) between the trace and the reference ground plane.
In order to respect this constraint, Sierra Wireless recommends that a MicroStrip structure be used
and trace width be computed with a simulation tool (such as AppCAD, shown in the figure below and
available free of charge at http://www.avagotech.com).
Figure 1. AppCAD Screenshot for Microstrip Design Power Mode Diagram
The trace width should be wide enough to maintain reasonable insertion loss and manufacturing
reliability. Cutting out inner layers of ground under the trace will increase the effective substrate height;
therefore, increasing the width of the RF trace.
Caution: It is critical that no other signals (digital, analog, or supply) cross under the RF path. The figure
below shows a generic example of good and poor routing techniques.
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Hardware Integration Guide
Routing Constraints and
Recommendations
Poor routing
Correct routing
The yellow traces cross the RF trace.
There is no signal around the RF path.
Figure 2. RF Routing Examples
Fill the area around the RF traces with ground and ground vias to connect inner ground layers
for isolation.
Cut out ground fill under RF signal pads to reduce stray capacitance losses.
Avoid routing RF traces with sharp corners. A smooth radius is recommended.
E.g. Use of 45° angles instead of 90°.
The ground reference plane should be a solid continuous plane under the trace.
The coplanar clearance (G, below) from the trace to the ground should be at least the trace
width (W) and at least twice the height (H). This reduces the parasitic capacitance, which
potentially alters the trace impedance and increases the losses.
E.g. If W = 100 microns then G = 200 microns in an ideal setup. G = 150 microns would also
be acceptable is space is limited.
Figure 3. Coplanar Clearance Example
Note: The figure above shows several internal ground layers cut out, which may not be necessary for
every application.
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Hardware Integration Guide
Routing Constraints and
Recommendations
Figure 4. Antenna Microstrip Routing Example
5.2. Power and Ground Recommendations
Power and ground routing is critical to achieving optimal performance of the AirPrime AR7552 devices
when integrated into an application.
Recommendations:
Do not use a separate GND for the Antennas
Connections to GND from the AirPrime AR7552 should be flooded plane using thermal reliefs
to ensure reliable solder joints.
VBATT is recommended to be routed as a wide trace(s) directly from the 4V supply to the
LGA pad.
5.3. Antenna Recommendations
The AirPrime AR755x devices are designed to provide diagnostics status of the antennas connected
to it.
The Primary antenna interface is optimized for a multiband cellular antenna with a 10 kΩ DC
impedance between the antenna element and the ground reference.
The GNSS antenna interface is optimized for a 5V active GNSS antenna supporting the GPS
L1 and GLONASS L1 FDMA bands. Refer to GNSS Antenna Diagnostics section.
Connecting the antenna ground reference to the vehicle chassis is not recommended since that has
been known to cause noise from the engine to couple into the audio of the device. It is ultimately up to
the integrator to evaluate this performance.
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Hardware Integration Guide
Routing Constraints and
Recommendations
5.4. Interface Circuit Recommendations
The recommended interface implementation is to use open-drain non-inverting buffers with pull-ups to
the appropriate voltage reference. This allows a host processor operating at a different voltage to
communicate with the AirPrime AR7552 using the appropriate voltage levels.
The figure below is a reference circuit for a digital input signal to the AirPrime AR7552 device.
OVT
VCC
Output from
App
Input to AirPrime AR module
VCC_1V8
Vref of APP
Figure 5. AirPrime AR7552 Input Reference Circuit
The figure below is a reference circuit for a digital output signal from the AirPrime AR7552 device.
OVT
VCC Output from
AirPrime AR moduleInput to App
Vref of APP
VCC_1V8
Figure 6. AirPrime AR7552 Output Reference Circuit
The open-drain non-inverting buffer used in the reference circuits above is the OnSemi NL17SZ07.
Tip: The NL17SZ07 is over-voltage tolerant on the inputs. It may be possible to power all the buffers
from the 1.8V reference voltage output. Review the digital output characteristics of the applications
drivers and the Input characteristics of the buffer selected to determine if this would work in your
application.
If a Digital IO signal is used bidirectional in the application then a bidirectional buffer or bidirectional
level translator is needed.
Note: The AR7552 modem is granted with a modular approval for mobile applications. During FCC/IC
testing, the antenna trace of the AirPrime AR7552 embedded module which located on the CCB are
defined in the table below.
4117336 Rev 1.0 May 18, 2015 21
Hardware Integration Guide
Routing Constraints and
Recommendations
Table 19. The specification of RF Trace of The CCB, Main Port
Length-1
(mm)
Length-2
(mm)
Length-3
(mm)
Angel 1
(degree)
Angel 2
(degree)
Width
(mm)
Main Port
3.9
19.79
5.86
135
135
1.58
Table 20. The specification of RF Trace of The CCB, Diversity and GPS Port
Length (mm)
Width (mm)
Diversity Port
24.35
1.58
GPS Port
27.01
1.58
* Diversity Port is for Rx only.
The figure below is the RF trace in AR7552 CCB.
Figure 7. The definition of RF trace in the AR7552 CCB
Integrators may use the AR7552 modem in their final products without additional FCC/IC (Industry
Canada) certification if they meet the above design in AR7552 CCB. Otherwise, FCC/IC Class II
Permissive change need be obtained.
Angel 1
Angel 2
4117336 Rev 1.0 May 18, 2015 22
6. Regulatory Information
6.1. Important Notice
Because of the nature of wireless communications, transmission and reception of data can
never be guaranteed. Data may be delayed, corrupted (i.e., have errors) or be totally lost.
Although significant delays or losses of data are rare when wireless devices such as the
Sierra Wireless modem are used in a normal manner with a well-constructed network, the
Sierra Wireless modem should not be used in situations where failure to transmit or receive
data could result in damage of any kind to the user or any other party, including but not
limited to personal injury, death, or loss of property. Sierra Wireless and its affiliates accept
no responsibility for damages of any kind resulting from delays or errors in data transmitted
or received using Sierra Wireless modem, or for failure of the Sierra Wireless modem to
transmit or receive such data.
6.2. Safety and Hazards
Do not operate the AR7552 modem:
In areas where blasting is in progress
Where explosive atmospheres may be present including refueling points, fuel
depots, and chemical plants
Near medical equipment, life support equipment, or any equipment which may be
susceptible to any form of radio interference. In such areas, the AR Series device
MUST BE POWERED OFF. Otherwise, the AR Series device can transmit signals
that could interfere with this equipment
In an aircraft, the AR Series device MUST BE POWERED OFF. Otherwise, the AR
Series device can transmit signals that could interfere with various onboard systems
and may be dangerous to the operation of the aircraft or disrupt the cellular network.
Use of cellular phone in aircraft is illegal in some jurisdictions. Failure to observe this
instruction may lead to suspension or denial of cellular telephone services to the
offender, or legal action or both.
Some airlines may permit the use of cellular phones while the aircraft is on the
ground and the door is open. The AR Series device may be used normally at this
time.
6.3. Important Compliance Information for
USA OEM Integrators
The AR Series device is granted with a modular approval for mobile applications. Integrators
may use the AR Series device in their final products without additional FCC/IC (Industry
Canada) certification if they meet the following conditions. Otherwise, additional FCC/IC
approvals must be obtained.
1. At least 20cm separation distance between the antenna and the user’s body must
be maintained at all times.
2. To comply with FCC/IC regulations limiting both maximum RF output power and
human exposure to RF radiation, the maximum antenna gain including cable loss in
4117336 Rev 1.0 May 18, 2015 23
Hardware Integration Guide
Regulatory Information
a mobile-only exposure condition must not exceed the gain values presented in the
table below:
5.0 dBi in Cellular band
5.0 dBi in PCS band
5.0 dBi in LTE Band 4
7.0 dBi in LTE Band 7
5.0 dBi in LTE Band 17
3. The AR7552 modem may transmit simultaneously with other collocated radio
transmitters within a host device, provided the following conditions are met:
Each collocated radio transmitter has been certfied by FCC / IC for mobile
application.
At least 20 cm separation distance between the antennas of the collocated
transmitters and the user’s body must be maintained at all times.
The output power and antenna gain must not exceed the limits and configu-
rations stipulated in the following table.
Device
Technology
Band
Frequency
(MHz)
Maximum
conducted power
Maximum
antenna gain
AR7552
Module
LTE
2
1850-1910
25.0
5
4
1710-1755
25.0
5
5
824-849
25.0
5
7
2500 – 2570
25.7
7
17
704-716
25.0
5
UMTS
2
1850-1910
25.7
5
5
824-849
25.7
5
Collocated
transmitters1
WLAN
2400-2500
29
5
5150-580
29
5
WiMAX
2300-2400
29
5
2500-2700
29
5
3300-3800
29
5
BT
2400-2500
15
5
1. Valid collocated Transmitter combinations: WLAN+BT; WiMAX+BT. (WLAN+WiMAX+BT is not permitted.)
4. A label must be affixed to the outside of the end product into which the AirPrime
AR7552 device is incorporated, with a statement similar to the following:
This device contains FCC ID: N7NAR7552
This equipment contains equipment certified under IC: 2417C-AR7552
5. A user manual with the end product must clearly indicate the operating requirements
and conditions that must be observed to ensure compliance with current FCC/IC RF
exposure guidelines.
The end product with an embedded AirPrime AR7552 device may also need to pass the
FCC Part 15 unintentional emission testing requirements and be properly authorized.
Note: If this module is intended for use in a portable device, you are responsible for separate
approval to satisfy the SAR requirements of FCC Part 2.1093 and IC RSS-102.
4117336 Rev 1.0 May 18, 2015 24
7. References
7.1. Reference Documents
The table below lists the reference specifications for this product.
Table 21. Reference Specifications
Ref
Title
Issuer
[1]
Recommended Minimum Performance Standards for
cdma2000 High Rate Packet Data Access Terminal – C.S0033
3GPP2
[2]
Recommended Minimum Performance Standards for
cdma2000 Spread Spectrum Mobile Stations – C.S0011 (IS-98D)
3GPP2
[3]
Universal Serial Bus Specification
USB Implementers Forum
[4]
Universal Serial Bus CDC Subclass Specification for Wireless Mobile
Communication Devices
USB Implementers Forum
[5]
Universal Serial Bus Class Definitions for Communication Devices
USB Implementers Forum
[6]
AirPrime AR Series Customer Process Guidelines
Sierra Wireless
[7]
AirPrime AR7 Series AT Command Interface Specification
Sierra Wireless
[8]
AirPrime AR7 Series Firmware Download Guide
Sierra Wireless
7.2. Abbreviations
The table below lists several abbreviations used in this document.
Table 22. Abbreviations
Abbreviation
Description
CDMA
Code Division Multiple Access
DRX
Discontinuous Receive
GNSS
Global Navigation Satellite System
GSM
Global System for Mobile Communications
HSPA
High Speed Packet Access
LTE
Long Term Evolution
SCI
Slot Cycle Index
USB
Universal Serial Bus
WCDMA
Wideband Code Division Multiple Access
WWAN
Wireless Wide Area Network