Quectel M85 User manual

M85 Hardware Design
GSM/GPRS Module Series
Rev. M85_Hardware_Design_V3.0
Date: 2015-10-22
www.quectel.com

GSM/GPRS Module Series
M85 Hardware Design
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About the Document
History
Revision
Date
Author
Description
1.0
2012-07-15
Winter CHEN
Initial
1.1
2013-11-04
Felix YIN
Optimized the parameters of VBAT ripple in Table 33
3.0
2015-03-13
Stone YU/
Hollis WANG
1. Updated module key features in Table 1
2. Modified pin assignment in Figure 2
3. Updated DC characteristics of module’s pins in
Table 4
4. Updated reference circuit for power supply in
Figure 5
5. Modified over-voltage or under-voltage automatic
shutdown in Section 3.4.2.3
6. Modified RTC backup in Section 3.6
7. Modified UART application in Section 3.7.4
8. Deleted the data call mode in Section 3.13
9. Added antenna requirement in Section 4.5

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Contents
About the Document...................................................................................................................................2
Contents.......................................................................................................................................................3
Table Index...................................................................................................................................................6
Figure Index.................................................................................................................................................7
1Introduction..........................................................................................................................................9
1.1. Safety Information .................................................................................................................10
2Product Concept................................................................................................................................11
2.1. General Description...............................................................................................................11
2.2. Directives and Standards ...................................................................................................... 11
2.2.1. FCC Statement............................................................................................................... 11
2.2.2. FCC Radiation Exposure Statement..............................................................................12
2.3. Key Features.........................................................................................................................12
2.4. Functional Diagram...............................................................................................................14
2.5. Evaluation Board...................................................................................................................15
3Application Interface .........................................................................................................................16
3.1. Pin of Module.........................................................................................................................17
3.1.1. Pin Assignment ..............................................................................................................17
3.1.2. Pin Description...............................................................................................................18
3.2. Operating Modes...................................................................................................................23
3.3. Power Supply ........................................................................................................................24
3.3.1. Power Features of Module.............................................................................................24
3.3.2. Decrease Supply Voltage Drop......................................................................................24
3.3.3. Reference Design For Power Supply ............................................................................25
3.3.4. Monitor Power Supply....................................................................................................26
3.4. Power On and Down Scenarios............................................................................................26
3.4.1. Power On .......................................................................................................................26
3.4.2. Power Down...................................................................................................................28
3.4.2.1. Power Down Module Using the PWRKEY Pin................................................28
3.4.2.2. Power Down Module Using AT Command......................................................29
3.4.2.3. Over-voltage or Under-voltage Automatic Shutdown......................................29
3.4.2.4. Emergency Shutdown Using EMERG_OFF Pin.............................................30
3.4.3. Restart............................................................................................................................31
3.5. Power Saving ........................................................................................................................32
3.5.1. Minimum Functionality Mode.........................................................................................32
3.5.2. SLEEP Mode..................................................................................................................33
3.5.3. Wake up Module from SLEEP Mode.............................................................................33
3.5.4. Summary of State Transition..........................................................................................33
3.6. RTC Backup ..........................................................................................................................34

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3.7. Serial Interfaces.....................................................................................................................36
3.7.1. UART Port......................................................................................................................38
3.7.1.1. The Features of UART Port.............................................................................38
3.7.1.2. The Connection of UART Port.........................................................................39
3.7.1.3. Firmware Upgrade...........................................................................................40
3.7.2. Debug Port.....................................................................................................................41
3.7.3. Auxiliary UART Port .......................................................................................................42
3.7.4. UARTApplication...........................................................................................................42
3.8. Audio Interfaces.....................................................................................................................44
3.8.1. Decrease TDD Noise and Other Noise..........................................................................45
3.8.2. Microphone Interfaces Design.......................................................................................46
3.8.3. Receiver and Speaker Interface Design........................................................................46
3.8.4. Earphone Interface Design............................................................................................48
3.8.5. Loud Speaker Interface Design......................................................................................49
3.8.6. Audio Characteristics.....................................................................................................49
3.9. SIM Card Interfaces ..............................................................................................................50
3.10. SD Card Interface..................................................................................................................53
3.11. PCM Interface........................................................................................................................55
3.11.1. Configuration..................................................................................................................56
3.11.2. Timing.............................................................................................................................56
3.11.3. Reference Design ..........................................................................................................58
3.11.4. AT Command .................................................................................................................58
3.12. ADC.......................................................................................................................................59
3.13. Behaviors Of The RI..............................................................................................................60
3.14. Network Status Indication......................................................................................................62
3.15. Operating Status Indication...................................................................................................62
4Antenna Interface...............................................................................................................................64
4.1. Reference Design..................................................................................................................64
4.2. RF Output Power...................................................................................................................65
4.3. RF Receiving Sensitivity........................................................................................................65
4.4. Operating Frequencies..........................................................................................................66
4.5. Antenna Requirement ...........................................................................................................66
4.6. RF Cable Soldering...............................................................................................................67
5Electrical, Reliability and Radio Characteristics............................................................................68
5.1. Absolute Maximum Ratings...................................................................................................68
5.2. Operating Temperature .........................................................................................................69
5.3. Power Supply Ratings...........................................................................................................69
5.4. Current Consumption............................................................................................................70
5.5. Electro-static Discharge ........................................................................................................72
6Mechanical Dimensions....................................................................................................................74
6.1. Mechanical Dimensions of Module .......................................................................................74
6.2. Recommended Footprint.......................................................................................................76
6.3. Top View of the Module.........................................................................................................77

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6.4. Bottom View of the Module ...................................................................................................77
7Storage and Manufacturing ..............................................................................................................78
7.1. Storage..................................................................................................................................78
7.2. Soldering ...............................................................................................................................79
7.3. Packaging..............................................................................................................................80
8Appendix A Reference.......................................................................................................................82
9Appendix B GPRS Coding Scheme.................................................................................................87
10 Appendix C GPRS Multi-slot Class..................................................................................................89

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Table Index
TABLE 1: MODULE KEY FEATURES............................................................................................................... 12
TABLE 2: CODING SCHEMES AND MAXIMUM NET DATA RATES OVER AIR INTERFACE........................ 14
TABLE 3: PIN DESCRIPTION........................................................................................................................... 18
TABLE 4: OVERVIEW OF OPERATING MODES............................................................................................. 23
TABLE 5: SUMMARY OF STATE TRANSITION ............................................................................................... 33
TABLE 6: LOGIC LEVELS OF THE UART INTERFACE .................................................................................. 37
TABLE 7: PIN DEFINITION OF THE UART INTERFACES .............................................................................. 37
TABLE 8: PIN DEFINITION OF AUDIO INTERFACE ....................................................................................... 44
TABLE 9: AOUT3 OUTPUT CHARACTERISTICS............................................................................................ 45
TABLE 10: TYPICAL ELECTRET MICROPHONE CHARACTERISTICS......................................................... 49
TABLE 11: TYPICAL SPEAKER CHARACTERISTICS..................................................................................... 49
TABLE 12: PIN DEFINITION OF THE SIM INTERFACE.................................................................................. 50
TABLE 13: PIN DEFINITION OF THE SD CARD INTERFACE........................................................................ 54
TABLE 14: PIN DEFINITION OF THE SD CARD INTERFACE........................................................................ 54
TABLE 15: PIN DEFINITION OF PCM INTERFACE......................................................................................... 55
TABLE 16: CONFIGURATION........................................................................................................................... 56
TABLE 17: QPCMON COMMAND DESCRIPTION .......................................................................................... 59
TABLE 18: QPCMVOL COMMAND DESCRIPTION......................................................................................... 59
TABLE 19: PIN DEFINITION OF THE ADC ...................................................................................................... 60
TABLE 20: CHARACTERISTICS OF THE ADC................................................................................................ 60
TABLE 21: BEHAVIORS OF THE RI................................................................................................................. 60
TABLE 22: WORKING STATE OF THE NETLIGHT.......................................................................................... 62
TABLE 23: PIN DEFINITION OF THE STATUS................................................................................................ 63
TABLE 24: PIN DEFINITION OF THE RF_ANT................................................................................................ 64
TABLE 25: THE MODULE CONDUCTED RF OUTPUT POWER .................................................................... 65
TABLE 26: THE MODULE CONDUCTED RF RECEIVING SENSITIVITY....................................................... 65
TABLE 27: THE MODULE OPERATING FREQUENCIES................................................................................ 66
TABLE 28: ANTENNACABLE REQUIREMENTS............................................................................................. 66
TABLE 29: ANTENNA REQUIREMENTS.......................................................................................................... 66
TABLE 30: ABSOLUTE MAXIMUM RATINGS .................................................................................................. 68
TABLE 31: OPERATING TEMPERATURE........................................................................................................ 69
TABLE 32: THE MODULE POWER SUPPLY RATINGS .................................................................................. 69
TABLE 33: THE MODULE CURRENT CONSUMPTION.................................................................................. 70
TABLE 34: THE ESD ENDURANCE (TEMPERATURE: 25ºC , HUMIDITY: 45%)............................................ 73
TABLE 35: REEL PACKING .............................................................................................................................. 81
TABLE 36: RELATED DOCUMENTS................................................................................................................ 82
TABLE 37: TERMS AND ABBREVIATIONS...................................................................................................... 83
TABLE 38: DESCRIPTION OF DIFFERENT CODING SCHEMES .................................................................. 87
TABLE 39: GPRS MULTI-SLOT CLASSES ...................................................................................................... 89

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Figure Index
FIGURE 1: MODULE FUNCTIONAL DIAGRAM............................................................................................... 15
FIGURE 2: PIN ASSIGNMENT ......................................................................................................................... 17
FIGURE 3: VOLTAGE RIPPLE DURING TRANSMITTING .............................................................................. 24
FIGURE 4: REFERENCE CIRCUIT FOR THE VBAT INPUT ........................................................................... 25
FIGURE 5: REFERENCE CIRCUIT FOR POWER SUPPLY............................................................................ 25
FIGURE 6: TURN ON THE MODULE WITH AN OPEN-COLLECTOR DRIVER.............................................. 26
FIGURE 7: TURN ON THE MODULE WITH A BUTTON.................................................................................. 27
FIGURE 8: TURN-ON TIMING.......................................................................................................................... 27
FIGURE 9: TURN-OFF TIMING........................................................................................................................ 28
FIGURE 10: AN OPEN-COLLECTOR DRIVER FOR EMERG_OFF................................................................ 30
FIGURE 11: REFERENCE CIRCUIT FOR EMERG_OFF BY USING BUTTON.............................................. 31
FIGURE 12: TIMING OF RESTARTING SYSTEM............................................................................................ 31
FIGURE 13: TIMING OF RESTARTING SYSTEM AFTER EMERGENCY SHUTDOWN ................................ 32
FIGURE 14: VRTC IS SUPPLIED BY A NON-CHARGEABLE BATTERY........................................................ 35
FIGURE 15: VRTC IS SUPPLIED BY A RECHARGEABLE BATTERY............................................................ 35
FIGURE 16: VRTC IS SUPPLIED BY A CAPACITOR ...................................................................................... 36
FIGURE 17: REFERENCE DESIGN FOR FULL-FUNCTION UART................................................................ 39
FIGURE 18: REFERENCE DESIGN FOR UART PORT................................................................................... 40
FIGURE 19: REFERENCE DESIGN FOR UART PORT WITH HARDWARE FLOW CONTROL.................... 40
FIGURE 20: REFERENCE DESIGN FOR FIRMWARE UPGRADE................................................................. 41
FIGURE 21: REFERENCE DESIGN FOR DEBUG PORT ............................................................................... 41
FIGURE 22: REFERENCE DESIGN FOR AUXILIARY UART PORT............................................................... 42
FIGURE 23: LEVEL MATCH DESIGN FOR 3.3V SYSTEM.............................................................................. 42
FIGURE 24: SKETCH MAP FOR RS-232 INTERFACE MATCH...................................................................... 43
FIGURE 25: REFERENCE DESIGN FOR AIN1&AIN2..................................................................................... 46
FIGURE 26: HANDSET INTERFACE DESIGN FOR AOUT1........................................................................... 46
FIGURE 27: SPEAKER INTERFACE DESIGN WITH AN AMPLIFIER FOR AOUT1 ....................................... 47
FIGURE 28: HANDSET INTERFACE DESIGN FOR AOUT2 ........................................................................... 47
FIGURE 29: SPEAKER INTERFACE DESIGN WITH AN AMPLIFIER FOR AOUT2 ....................................... 48
FIGURE 30: EARPHONE INTERFACE DESIGN.............................................................................................. 48
FIGURE 31: LOUD SPEAKER INTERFACE DESIGN...................................................................................... 49
FIGURE 32: REFERENCE CIRCUIT FOR SIM1 INTERFACE WITH 8-PIN SIM CARD HOLDER ................. 51
FIGURE 33: REFERENCE CIRCUIT FOR SIM1 INTERFACE WITH THE 6-PIN SIM CARD HOLDER ......... 52
FIGURE 34: REFERENCE CIRCUIT FOR SIM2 INTERFACE WITH THE 6-PIN SIM CARD HOLDER ......... 52
FIGURE 35: REFERENCE CIRCUIT FOR SD CARD ...................................................................................... 54
FIGURE 36: LONG SYNCHRONIZATION & SIGN EXTENSION DIAGRAM................................................... 57
FIGURE 37: LONG SYNCHRONIZATION & ZERO PADDING DIAGRAM....................................................... 57
FIGURE 38: SHORT SYNCHRONIZATION & SIGN EXTENSION DIAGRAM................................................. 57
FIGURE 39: SHORT SYNCHRONIZATION & ZERO PADDING DIAGRAM .................................................... 58
FIGURE 40: REFERENCE DESIGN FOR PCM ............................................................................................... 58
FIGURE 41: RI BEHAVIOR OF VOICE CALLING AS A RECEIVER................................................................ 61
FIGURE 42: RI BEHAVIOR AS A CALLER ....................................................................................................... 61

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FIGURE 43: RI BEHAVIOR OF URC OR SMS RECEIVED ............................................................................. 61
FIGURE 44: REFERENCE DESIGN FOR NETLIGHT ..................................................................................... 62
FIGURE 45: REFERENCE DESIGN FOR STATUS.......................................................................................... 63
FIGURE 46: REFERENCE DESIGN FOR RF .................................................................................................. 64
FIGURE 47: RF SOLDERING SAMPLE ........................................................................................................... 67
FIGURE 48: M85 MODULE TOP AND SIDE DIMENSIONS (UNIT: MM)......................................................... 74
FIGURE 49: M85 MODULE BOTTOM DIMENSIONS (UNIT: MM)................................................................... 75
FIGURE 50: THE PAD DIMENSIONS (UNIT: MM) ........................................................................................... 75
FIGURE 51: RECOMMENDED FOOTPRINT (UNIT: MM)................................................................................ 76
FIGURE 52: TOP VIEW OF THE MODULE...................................................................................................... 77
FIGURE 53: BOTTOM VIEW OF THE MODULE.............................................................................................. 77
FIGURE 54: RAMP-SOAK-SPIKE REFLOW PROFILE.................................................................................... 79
FIGURE 55: TAPE AND REEL INFORMATION ................................................................................................ 81
FIGURE 56: RADIO BLOCK STRUCTURE OF CS-1, CS-2 AND CS-3........................................................... 87
FIGURE 57: RADIO BLOCK STRUCTURE OF CS-4....................................................................................... 88

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1Introduction
This document defines the M85 module and describes its hardware interface which are connected with
the customer application and the air interface.
This document can help you quickly understand module interface specifications, electrical and
mechanical details. Associated with application notes and user guide, you can use M85 module to design
and set up mobile applications easily.

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1.1. Safety Information
The following safety precautions must be observed during all phases of the operation, such as usage,
service or repair of any cellular terminal or mobile incorporating M85 module. Manufacturers of the
cellular terminal should send the following safety information to users and operating personnel and to
incorporate these guidelines into all manuals supplied with the product. If not so, Quectel does not take on
any liability for customer failure to comply with these precautions.
Full attention must be given to driving at all times in order to reduce the risk of an
accident. Using a mobie while driving (even with a handsfree kit) cause distraction
and can lead to an accident. You must comply with laws and regulations restrcting
the use of wireless devices while driving.
Switch off the cellular terminal or mobile before boarding an aircraft. Make sure it
switched off. The operation of wireless appliances in an aircraft is forbidden to
prevent interference with communication systems. Consult the airline staff about
the use of wireless devices on boarding the aircraft. If your device offers a Flight
Mode which must be enabled prior to boarding an aircraft.
Switch off your wireless device when in hospitals or clinics or other health care
facilities. These requests are desinged to prevent possible interference with
sentitive medical equipment.
Cellular terminals or mobiles operate over radio frequency signal and cellular
network and cannot be guaranteed to connect in all conditions, for example no
mobile fee or an invalid SIM card. While you are in this condition and need
emergent help, please remember using emergency call. In order to make or
receive call, the cellular terminal or mobile must be switched on and in a service
area with adequate cellular signal strength.
Your cellular terminal or mobile contains a transmitter and receiver. When it is ON ,
it receives and transmits radio frequency energy. RF interference can occur if it is
used close to TV set, radio, computer or other electric equipment.
In locations with potencially explosive atmospheres, obey all posted signs to turn
off wireless devices such as your phone or other cellular terminals. Areas with
potencially exposive atmospheres including fuelling areas, below decks on boats,
fuel or chemical transfer or storage facilities, areas where the air contains
chemicals or particles such as grain, dust or metal powders.

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2Product Concept
2.1. General Description
M85 is a Quad-band GSM/GPRS engine that works at frequencies of GSM850MHz, EGSM900MHz,
DCS1800MHz and PCS1900MHz. The M85 features GPRS multi-slot class 12 and supports the GPRS
coding schemes CS-1, CS-2, CS-3 and CS-4. For more details about GPRS multi-slot classes and coding
schemes, please refer to the Appendix B & C.
With a tiny profile of 24.5mm ×25.3mm ×2.6mm, the module can meet almost all the requirements for
M2M applications, including Vehicles and Personal Tracking, Security System, Wireless POS, Industrial
PDA, Smart Metering, and Remote Maintenance & Control, etc.
M85 is an SMD type module with LCC package, which can be easily embedded into applications. It
provides abundant hardware interfaces like PCM and SD Card Interface.
Designed with power saving technique, the current consumption of M85 is as low as 1.3 mA in SLEEP
mode when DRX is 5.
M85 is integrated with Internet service protocols, such as TCP/UDP, FTP and PPP. Extended AT
commands have been developed for you to use these Internet service protocols easily.
The module fully complies with the RoHS directive of the European Union.
2.2. Directives and Standards
The M85 module is designed to comply with the FCC statements. FCC ID: XMR201511M85
The Host system using M85 should have label ―contains FCC ID: XMR201511M85‖.
2.2.1. FCC Statement
Changes or modifications not expressly approved by the party responsible for compliance could void the
user’s authority to operate the equipment.

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2.2.2. FCC Radiation Exposure Statement
This equipment complies with FCC radiation exposure limits set forth for an uncontrolled environment.
This equipment should be installed and operated with minimum distance 20cm between the radiator and
your body as well as kept minimum 20cm from radio antenna depending on the Mobile status of this
module usage. This module should NOT be installed and operating simultaneously with other radio. The
manual of the host system, which uses M85, must include RF exposure warning statement to advice user
should keep minimum 20cm from the radio antenna of M85 module depending on the Mobile status. Note:
If a portable device (such as PDA) uses M85 module, the device needs to do permissive change and SAR
testing.
The following list indicates the performance of antenna gain in certificate testing.
2.3. Key Features
The following table describes the detailed features of M85 module.
Table 1: Module Key Features
Feature
Implementation
Power Supply
Single supply voltage: 3.3V~4.6V
Typical supply voltage: 4.0V
Power Saving
Typical power consumption in SLEEP mode: 1.3 mA@ DRX=5
1.2 mA@ DRX=9
Frequency Bands
Quad-band: GSM850, EGSM900, DCS1800, PCS1900
The module can search these frequency bands automatically
The frequency bands can be set byAT command
Compliant to GSM Phase 2/2+
GSM Class
Small MS
Transmitting Power
Class 4 (2W) at GSM850 and EGSM900
Class 1 (1W) at DCS1800 and PCS1900
Part
Number
Frequency Range (MHz)
Peak Gain
(XZ-V)
Average
Gain(XZ-V)
VS
WR
Impedanc
e
GSM850:824～894MHz
3R007
EGSM900:880～960MHz
DCS1800:1710～1880MHz
1 dBi typ.
1 dBi typ.
2 max
50Ω
PCS1900: 1850～1990MHz

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GPRS Connectivity
GPRS multi-slot class 12 (default)
GPRS multi-slot class 1~12 (configurable)
GPRS mobile station class B
DATA GPRS
GPRS data downlink transfer: max. 85.6kbps
GPRS data uplink transfer: max. 85.6kbps
Coding scheme: CS-1, CS-2, CS-3 and CS-4
Support the protocols PAP (Password Authentication Protocol)
usually used for PPP connections
Internet service protocols:
TCP/UDP/FTP/PPP/HTTP/NTP/MMS/SMTP/PING
Support Packet Broadcast Control Channel (PBCCH)
Support Unstructured Supplementary Service Data (USSD)
Temperature Range
Normal operation: -35°C ~ +80°C
Restricted operation: -40°C ~ -35°C and +80°C ~ +85°C 1)
Storage temperature: -45°C ~ +90°C
SMS
Text and PDU mode
SMS storage: SIM card
SIM Interfaces
Support SIM card: 1.8V, 3V
Audio Features
Speech codec modes:
Half Rate (ETS 06.20)
Full Rate (ETS 06.10)
Enhanced Full Rate (ETS 06.50/06.60/06.80)
Adaptive Multi-Rate (AMR)
Echo Suppression
Noise Reduction
Embedded one amplifier of class AB with maximum driving power up
to 870mW
UART Interfaces
UART Port:
Seven lines on UART port interface
Used for AT command, GPRS data
Multiplexing function
Support autobauding from 4800bps to 115200bps
Debug Port:
Two lines on debug port interface DBG_TXD and DBG_RXD
Use for software debugging and log output
Auxiliary Port:
Used for AT command
Phonebook Management
Support phonebook types: SM, ME, ON, MC, RC, DC, LD, LA
SIM Application Toolkit
Support SAT class 3, GSM 11.14 Release 99
Real Time Clock
Supported

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1) When the module works within this temperature range, the deviations from the GSM specification may
occur. For example, the frequency error or the phase error will be increased.
Table 2: Coding Schemes and Maximum Net Data Rates over Air Interface
2.4. Functional Diagram
The following figure shows a block diagram of M85 and illustrates the major functional parts.
Radio frequency part
Serial Flash
Power management
The Peripheral interface
—Power supply
—Turn-on/off interface
—UART interfaces
—Audio interfaces
—SIM interfaces
—SD interface
—PCM interface
—ADC interface
—RTC interface
Physical Characteristics
Size: 25.3±0.15 ×24.5±0.15 ×2.6±0.2mm
Weight: Approx. 3.3g
Firmware Upgrade
Firmware upgrade via UART Port
Antenna Interface
Connected to antenna pad with 50 Ohm impedance control
Coding scheme
1 Timeslot
2 Timeslot
4 Timeslot
CS-1
9.05kbps
18.1kbps
36.2kbps
CS-2
13.4kbps
26.8kbps
53.6kbps
CS-3
15.6kbps
31.2kbps
62.4kbps
CS-4
21.4kbps
42.8kbps
85.6kbps
NOTE

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—RF interface
BB&RF
RF PAM
26MHzRF Transceiver
RTC
GPIO&PWM
Serial Interface
SIM
Interface
RF_ANT
VBAT
PWRKEY
EMERG_OFF
VRTC
GPIO&
Status&
Netlight
UART
SIM Interfaces
Reset
ESD
PMU
MEMORY Audio Audio
PCM
Interface PCM
Serial Flash
SD
Interface
SD
ADC ADC
Figure 1: Module Functional Diagram
2.5. Evaluation Board
In order to help customer to develop applications with M85, Quectel supplies an evaluation board (EVB),
RS-232 to USB cable, power adapter, earphone, antenna and other peripherals to control or test the
module. For details, please refer to the document [12].

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3Application Interface
The module adopts LCC package and has 83 pins. The following chapters provide detailed descriptions
about these pins below.
Power supply
Power on/down
Power saving
RTC
Serial interfaces
Audio interfaces
SIM interfaces
SD interface
PCM interface
ADC
RI
NETLIGHT
Status

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3.1. Pin of Module
3.1.1. Pin Assignment
Power SIM1 RESERVED PCM
Other
SD
RESERVED
NETLIGHT
LOUDSPKN
LOUDSPKP
PWRKEY
EMERG_OFF
PCM_IN
PCM_CLK RESERVED
RESERVED
RESERVED
SIM_GND
SIM1_RST
SIM1_DATA
SIM1_CLK
SIM1_VDD
RESERVED
SIM2_VDD
SIM2_CLK
SIM2_DATA
SIM2_RST
SIM1_PRESENCE
GND Audio ADC
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
5758
59
60
616263646566676869
70
71727374
Top view
RFSIM2
VBAT UART
ADC0
RESERVED
SPK2P
AGND
MIC2P
MIC2N
MIC1P
MIC1N
SPK1N
SPK1P
STATUS
PCM_OUT
PCM_SYNC
RESERVED
RESERVED
RESERVED RESERVED RESERVED RESERVED RESERVED RESERVED RESERVED
RESERVED RESERVED
RESERVED
SD_CMD
SD_CLK
SD_DATA0
GND
TXD_AUX
RXD_AUX
DBG_TXD
DBG_RXD
DCD
RI
DTR
CTS
TXD
RXD
RTS
VRTC
VDD_EXT
GND
GND
RF_ANT
GND GND GND
VBAT VBAT VBAT
VBAT
75
76
77
78
79
80
81
82
RESERVED
RESERVED
RESERVED
RESERVED
GND
GND
GND
GND
RESERVED
83
Figure 2: Pin Assignment
Keep all reserved pins open.
NOTE

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3.1.2. Pin Description
Table 3: Pin Description
Power Supply
PIN NAME
PIN NO.
I/O
DESCRIPTION
DC
CHARACTERISTICS
COMMENT
VBAT
67, 68, 69,
70
I
Main power supply of
module:
VBAT=3.3V~4.6V
Vmax=4.6V
Vmin=3.3V
Vnorm=4.0V
Make sure that
supply sufficient
current in a
transmitting burst
typically rises to
1.6A.
VRTC
59
I/O
Power supply for RTC.
Charging for backup
battery or golden
capacitor when the
VBAT is applied.
VImax=3.3V
VImin=1.5V
VInorm=2.8V
VOmax=3V
VOmin=2V
VOnorm=2.8V
Iout(max)=2mA
Iin≈10uA
If unused, keep
this pin open.
VDD_EXT
60
O
Supply 2.8V voltage for
external circuit.
Vmax=2.9V
Vmin=2.7V
Vnorm=2.8V
Imax=20mA
1. If unused, keep
this pin open.
2. Recommend to
add a 2.2~4.7uF
bypass capacitor,
when using this
pin for power
supply.
GND
37, 61, 62,
64~66,
79~82,
Ground
Turn on/off
PIN NAME
PIN NO.
I/O
DESCRIPTION
DC
CHARACTERISTICS
COMMENT
PWRKEY
15
I
Power on/off key.
PWRKEY should be pulled
down for a moment to turn
on or turn off the system.
VILmax=
0.1×VBAT
VIHmin=
0.6×VBAT
VIHmax=3.1V
Emergency Shutdown

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M85 Hardware Design
M85_Hardware_Design Confidential / Released 19 / 88
PIN NAME
PIN NO.
I/O
DESCRIPTION
DC
CHARACTERISTICS
COMMENT
EMERG_
OFF
17
I
Emergency off. Pulled
down for at least 40ms,
which will turn off the
module in case of
emergency. Use it only
when shutdown via
PWRKEY or AT command
cannot be achieved.
VILmax=0.45V
VIHmin=1.35V
Vopenmax=1.8V
Open
drain/collector
driver required in
cellular device
application.
If unused, keep
this pin open.
Module Indicator
PIN NAME
PIN NO.
I/O
DESCRIPTION
DC
CHARACTERISTICS
COMMENT
STATUS
16
O
Indicate module’s
operating status. Output
high level when module
turns on, while output low
level when module turns
off.
VOHmin=
0.85×VDD_EXT
VOLmax=
0.15×VDD_EXT
If unused, keep
this pin open.
Audio Interface
PIN NAME
PIN NO.
I/O
DESCRIPTION
DC
CHARACTERISTICS
COMMENT
MIC1P
MIC1N
9, 10
I
Channel 1 positive and
negative voice input
Refer to Section 3.8
If unused, keep
these pins open.
MIC2P
MIC2N
7, 8
I
Channel 2 positive and
negative voice input
SPK1P
SPK1N
12, 11
O
Channel 1 positive and
negative voice output
1. If unused, keep
these pins open.
2. Support both
voice and
ringtone output.
SPK2P
5
O
Channel 2 voice output
AGND
6
Analog ground. Separate
ground connection for
external audio circuits.
If unused, keep
this pin open.
LOUDSPKN
LOUDSPKP
13, 14
O
Channel 3 positive and
negative voice output
1. If unused, keep
these pins open.
2. Integrate a
Class- AB
amplifier
internally.
3. Support both
voice and