Simcom 201607 User Manual

SIM868_User Manual_REV2

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General Notes

SIMCom offers this information as a service to its customers, to support application and engineering efforts that

use the products designed by SIMCom. The information provided is based upon requirements specifically

provided to SIMCom by the customers. SIMCom has not undertaken any independent search for additional

relevant information, including any information that may be in the customer’s possession. Furthermore, system

validation of this product designed by SIMCom within a larger electronic system remains the responsibility of the

customer or the customer’s system integrator. All specifications supplied herein are subject to change.

Copyright

This document contains proprietary technical information which is the property of SIMCom Limited, copying of

this document and giving it to others and the using or communication of the contents thereof, are forbidden

without express authority. Offenders are liable to the payment of damages. All rights reserved in the event of grant

of a patent or the registration of a utility model or design. All specification supplied herein are subject to change

without notice at any time.

Copyright © Shanghai SIMCom Wireless Solutions Ltd. 2016

Compliance Information

FCC Compliance Statement: This device complies with Part 15 of the FCC Rules . Operation is subject to the

following two conditions: 1. This device may not cause harmful interference, and 2. This device must accept

any interference received, including interference that may cause undesired operation. This device must accept

any interference received, including interference that may cause undesired operation. Product that is a radio

transmitter is labeled with FCC ID.

FCC Caution

(1) Exposure to Radio Frequency Radiation. This equipment must be installed and operated in accordance with

provided instructions and the antenna(s) used for this transmitter must be installed to provide a separation

distance of at least 20 cm from all persons and must not be collocated or operating in conjunction with any other

antenna or transmitter. End-users and installers must be provided with antenna installation instructions and

transmitter operating conditions for satisfying RF exposure compliance.

(2) Any changes or modifications not expressly approved by the grantee of this device could void the user's

authority to operate the equipment.

(3) This Transmitter must not be co-located or operating in conjunction with any other antenna or transmitter.

(4) Changes or modifications to this unit not expressly approved by the party responsible for compliance could

void the user authority to operate the equipment.

(5) The modules FCC ID is not visible when installed in the host, or

(6) If the host is marketed so that end users do not have straight forward commonly used methods for access to

remove the module so that the FCC ID of the module is visible; then an additional permanent label referring to

the enclosed module Contains Transmitter Module FCC ID: UDV-201607 or Contains UDV-201607 must be used.

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Contents

Version History ........................................................................................................ 9

1. Introduction .................................................................................................... 10

2. SIM868 Overview ........................................................................................... 10

2.1. SIM868 .......................................................................................................................... 10

2.2. SIM868 Key Features ..................................................................................................... 10

2.3. Operating Mode .............................................................................................................. 13

2.4. Functional Diagram ........................................................................................................ 14

3. Package Information ...................................................................................... 15

3.1. Pin Out Diagram ............................................................................................................. 15

3.2. Pin Description ............................................................................................................... 15

3.3. Package Dimensions ....................................................................................................... 18

4. Application Interface ...................................................................................... 20

4.1. Power Supply ................................................................................................................. 20

4.1.1. Power Supply Pin ................................................................................................................................ 21

4.1.2. Monitoring Power Supply ................................................................................................................... 22

4.2. Power on/off SIM868 ..................................................................................................... 22

4.2.1. Power on SIM868 ............................................................................................................................... 22

4.2.2. Power off SIM868 ............................................................................................................................... 23

4.3. Power Saving Mode........................................................................................................ 25

4.3.1. Minimum Functionality Mode ............................................................................................................ 25

4.3.2. Sleep Mode 1 (AT+CSCLK=1) .......................................................................................................... 25

4.3.3. Wake Up SIM868 from Sleep Mode 1 ................................................................................................ 25

4.3.4. Sleep Mode 2 (AT+CSCLK=2) .......................................................................................................... 26

4.3.5. Wake Up SIM868 from Sleep Mode 2 ................................................................................................ 26

4.4. Power Saving Mode........................................................................................................ 26

4.5. Serial Port and USB Interface ......................................................................................... 27

4.5.1 Function of Serial Port ........................................................................................................................ 28

4.5.2 Serial Interfaces ................................................................................................................................... 29

4.5.3 Debug Interface ................................................................................................................................... 30

4.5.4 Software Upgrade ................................................................................................................................ 31

4.6. UART1_RI Behaviors .................................................................................................... 31

4.7. Audio Interfaces ............................................................................................................. 32

4.7.1. Speaker Interfaces Configuration ........................................................................................................ 33

4.7.2. Microphone Interfaces Configuration ................................................................................................. 34

4.7.3. Audio Electronic Characteristic .......................................................................................................... 34

4.7.4. TDD .................................................................................................................................................... 34

4.8. SIM Card Interface ......................................................................................................... 35

4.8.1. SIM Card Application ......................................................................................................................... 35

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4.8.2. SIM Card Design Guide ...................................................................................................................... 36

4.8.3. Design Considerations for SIM Card Holder ...................................................................................... 37

4.9. SD Interface ................................................................................................................... 39

4.10. I2C Bus .......................................................................................................................... 39

4.10.1. I2C Multiplexing Function .............................................................................................................. 39

4.11. ADC ............................................................................................................................... 40

4.12. Network Status Indication............................................................................................... 40

4.13. Operating Status Indication ............................................................................................. 41

4.14. RF Synchronization Signal ............................................................................................. 41

4.14.1. RF_SYNC Multiplexing Function ................................................................................................... 42

4.15. GNSS ............................................................................................................................. 42

4.15.1. GNSS Overview .............................................................................................................................. 42

4.15.2. Power on/down GNSS ..................................................................................................................... 42

4.15.3. 1PPS Output..................................................................................................................................... 42

4.16. Antenna Interface ........................................................................................................... 42

4.16.1. GSM Antenna Interface ................................................................................................................... 43

4.16.2. GNSS Antenna Interface .................................................................................................................. 46

5. PCB Layout ..................................................................................................... 48

5.1 Pin Assignment .............................................................................................................. 48

5.2 Principle of PCB Layout ................................................................................................. 49

5.2.1 Antenna Interface ................................................................................................................................ 49

5.2.2 Power Supply ...................................................................................................................................... 49

5.2.3 SIM Card Interface .............................................................................................................................. 49

5.2.4 Audio Interface.................................................................................................................................... 49

5.2.5 Others .................................................................................................................................................. 49

6. Electrical, Reliability and Radio Characteristics .......................................... 50

6.1 Absolute Maximum Ratings ........................................................................................... 50

6.2 Recommended Operating Conditions .............................................................................. 50

6.3 Digital Interface Characteristics ...................................................................................... 50

6.4 SIM Card Interface Characteristics ................................................................................. 50

6.5 SIM_VDD Characteristics .............................................................................................. 51

6.6 VDD_EXT Characteristics ............................................................................................. 51

6.7 Current Consumption（VBAT=4.0V） .......................................................................... 51

6.8 Electro-Static Discharge ................................................................................................. 52

6.9 Radio Characteristics ...................................................................................................... 52

6.9.1 Module RF Output Power ................................................................................................................... 52

6.9.2 Module RF Receive Sensitivity ........................................................................................................... 54

6.9.3 Module Operating Frequencies ........................................................................................................... 54

7. Manufacturing ................................................................................................ 55

7.1. Top and Bottom View of SIM868 ................................................................................... 55

7.2. Typical Solder Reflow Profile ........................................................................................ 55

7.3. The Moisture Sensitivity Level ....................................................................................... 55

7.4. Baking Requirements ..................................................................................................... 56

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8. Appendix ......................................................................................................... 57

I. Related Documents ......................................................................................................... 57

II. Multiplexing Function .................................................................................................... 58

III. Terms and Abbreviations ................................................................................................ 58

IV. Safety Caution ................................................................................................................ 60

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Table Index

TABLE 1: MODULE INFORMATION ......................................................................................................................10

TABLE 2: SIM868 KEY FEATURES .........................................................................................................................10

TABLE 3: GNSS ENGINE PERFORMANCE ............................................................................................................12

TABLE 4: CODING SCHEMES AND MAXIMUM NET DATA RATES OVER AIR INTERFACE ...........................13

TABLE 5: OVERVIEW OF OPERATING MODES....................................................................................................13

TABLE 6: PIN DESCRIPTION ..................................................................................................................................15

TABLE 7: RECOMMENDED ZENER DIODE ..........................................................................................................20

TABLE 8: THE CURRENT CONSUMPTION OF FUNCTION MODE .....................................................................25

TABLE 9: SERIAL PORT AND USB PIN DEFINITION ...........................................................................................27

TABLE 10: SERIAL PORT CHARACTERISTICS.....................................................................................................27

TABLE 11: USB_VBUS OPERATION VOLTAGE ....................................................................................................31

TABLE 12: RI BEHAVIORS......................................................................................................................................31

TABLE 13: AUDIO INTERFACE DEFINITION........................................................................................................32

TABLE 14: PERFORMANCE OF AUDIO AMPLIFIER ............................................................................................33

TABLE 15: MICROPHONE INPUT CHARACTERISTICS .......................................................................................34

TABLE 16: AUDIO OUTPUT CHARACTERISTICS ................................................................................................34

TABLE 17: SIM PIN DEFINITION ...........................................................................................................................35

TABLE 18: PIN DESCRIPTION (MOLEX SIM CARD HOLDER) ...........................................................................37

TABLE 19: PIN DESCRIPTION (AMPHENOL SIM CARD HOLDER) ....................................................................38

TABLE 20: SD MULTIPLEXING FUNCTION ..........................................................................................................39

TABLE 21: PIN DEFINITION OF THE I2C ..............................................................................................................39

TABLE 22: I2C MULTIPLEXING FUNCTION .........................................................................................................39

TABLE 23: PIN DEFINITION OF THE ADC ............................................................................................................40

TABLE 24: ADC SPECIFICATION ...........................................................................................................................40

TABLE 25: PIN DEFINITION OF THE NETLIGHT .................................................................................................40

TABLE 26: STATUS OF THE NETLIGHT PIN .........................................................................................................40

TABLE 27: NETLIGHT MULTIPLEXING FUNCTION ............................................................................................41

TABLE 28: PIN DEFINITION OF THE STATUS ......................................................................................................41

TABLE 29: DEFINITION OF THE RF_SYNC PIN ...................................................................................................41

TABLE 30: RF_SYNC MULTIPLEXING FUNCTION ..............................................................................................42

TABLE 31: RECOMMENDED TVS COMPONENT .................................................................................................46

TABLE 32: ABSOLUTE MAXIMUM RATINGS ......................................................................................................50

TABLE 33: RECOMMENDED OPERATING CONDITIONS ....................................................................................50

TABLE 34: DIGITAL INTERFACE CHARACTERISTICS ........................................................................................50

TABLE 35: SIM CARD INTERFACE CHARACTERISTICS ....................................................................................50

TABLE 36: SIM_VDD CHARACTERISTICS ...........................................................................................................51

TABLE 37: VDD_EXT CHARACTERISTICS ...........................................................................................................51

TABLE 38: CURRENT CONSUMPTION..................................................................................................................51

TABLE 39: THE ESD CHARACTERISTICS (TEMPERATURE: 25℃, HUMIDITY: 45 %) ......................................52

TABLE 40: GSM850 AND EGSM900 CONDUCTED RF OUTPUT POWER............................................................53

TABLE 41: DCS1800 AND PCS1900 CONDUCTED RF OUTPUT POWER ............................................................53

TABLE 42: CONDUCTED RF RECEIVE SENSITIVITY..........................................................................................54

TABLE 43: OPERATING FREQUENCIES ................................................................................................................54

TABLE 44: MOISTURE SENSITIVITY LEVEL AND FLOOR LIFE ........................................................................56

TABLE 45: BAKING REQUIREMENTS...................................................................................................................56

TABLE 46: RELATED DOCUMENTS ......................................................................................................................57

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TABLE 47: MULTIPLEXING FUNCTION................................................................................................................58

TABLE 48: TERMS AND ABBREVIATIONS ...........................................................................................................58

TABLE 49: SAFETY CAUTION ...............................................................................................................................60

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Figure Index

FIGURE 1: SIM868 FUNCTIONAL DIAGRAM .......................................................................................................14

FIGURE 2: PIN OUT DIAGRAM (TOP VIEW).........................................................................................................15

FIGURE 3: DIMENSIONS OF SIM868 (UNIT: MM) ................................................................................................18

FIGURE 4: RECOMMENDED PCB FOOTPRINT OUTLINE (UNIT: MM) ..............................................................19

FIGURE 5: REFERENCE CIRCUIT OF THE VBAT/GPS_VBAT INPUT .................................................................20

FIGURE 6: REFERENCE CIRCUIT OF THE LDO POWER SUPPLY ......................................................................20

FIGURE 7: REFERENCE CIRCUIT OF THE DC-DC POWER SUPPLY ..................................................................21

FIGURE 8: VBAT VOLTAGE DROP DURING TRANSMIT BURST ........................................................................21

FIGURE 9: THE MINIMAL VBAT VOLTAGE REQUIREMENT AT VBAT DROP...................................................21

FIGURE 10: POWERED ON/DOWN MODULE USING TRANSISTOR ..................................................................22

FIGURE 11: POWERED ON/DOWN MODULE USING BUTTON ..........................................................................22

FIGURE 12: TIMING OF POWER ON MODULE.....................................................................................................22

FIGURE 13: TIMING OF POWER OFF SIM868 BY PWRKEY ................................................................................23

FIGURE 14: TIMING OF RESTART SIM868 ............................................................................................................24

FIGURE 15: RTC SUPPLY FROM CAPACITOR ......................................................................................................26

FIGURE 16: RTC SUPPLY FROM NON-CHARGEABLE BATTERY .......................................................................26

FIGURE 17: RTC SUPPLY FROM RECHARGEABLE BATTERY ...........................................................................27

FIGURE 18: CONNECTION OF THE SERIAL INTERFACES .................................................................................29

FIGURE 19: RESISTOR MATCHING CIRCUIT .......................................................................................................29

FIGURE 20 : DIODE ISOLATION CIRCUIT ............................................................................................................29

FIGURE 21: TX LEVEL MATCHING CIRCUIT .......................................................................................................30

FIGURE 22: RX LEVEL MATCHING CIRCUIT .......................................................................................................30

FIGURE 23: USB REFERENCE CIRCUIT ................................................................................................................30

FIGURE 24: CONNECTION FOR SOFTWARE UPGRADING AND DEBUGGING ................................................31

FIGURE 25: UART1_RI BEHAVIOUR OF VOICE CALLING AS A RECEIVER .....................................................32

FIGURE 26: UART1_RI BEHAVIOUR OF URC OR RECEIVE SMS .......................................................................32

FIGURE 27: UART1_RI BEHAVIOUR AS A CALLER .............................................................................................32

FIGURE 28: SPEAKER REFERENCE CIRCUIT ......................................................................................................33

FIGURE 29: MICROPHONE REFERENCE CIRCUIT ..............................................................................................34

FIGURE 30: REFERENCE CIRCUIT OF THE 8-PIN SIM CARD HOLDER ............................................................35

FIGURE 31: REFERENCE CIRCUIT OF THE 6-PIN SIM CARD HOLDER ............................................................36

FIGURE 32: MOLEX 91228 SIM CARD HOLDER ..................................................................................................37

FIGURE 33: AMPHENOL C707 10M006 512 SIM CARD HOLDER ........................................................................38

FIGURE 34: SD REFERENCE CIRCUIT ..................................................................................................................39

FIGURE 35: REFERENCE CIRCUIT OF NETLIGHT...............................................................................................41

FIGURE 36: RF_SYNC SIGNAL DURING TRANSMIT BURST .............................................................................42

FIGURE 37: GSM ANTENNA MATCHING CIRCUIT ..............................................................................................43

FIGURE 38: GSM ANTENNA MATCHING CIRCUIT WITHOUT RF CONNECTOR..............................................43

FIGURE 39: GNSS PASSIVE ANTENNA MATCHING CIRCUIT ............................................................................47

FIGURE 40: GNSS ACTIVE ANTENNA MATCHING CIRCUIT..............................................................................47

FIGURE 41: PIN ASSIGNMENT ..............................................................................................................................48

FIGURE 42: TOP AND BOTTOM VIEW OF SIM868 ...............................................................................................55

FIGURE 43: TYPICAL SOLDER REFLOW PROFILE OF LEAD-FREE PROCESS .................................................55

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Version History

Date Version Description of change Author

2016-06-20 1.00 Origin

Yanwu.Wang;

Xiaoxu.Chen

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1. Introduction

This document describes SIM868 hardware interface in great detail. The document can help customer to quickly

understand SIM868 interface specifications, electrical and mechanical details. With the help of this document

and other SIM868 application notes, customer guide, customers can use SIM868 to design various applications

quickly.

2. SIM868 Overview

Designed for global market, SIM868 is integrated with a high performance GSM/GPRS engine and a GNSS

engine. SIM868 is a quad-band GSM/GPRS module that works on frequencies GSM 850MHz, EGSM 900MHz,

DCS 1800MHz and PCS 1900MHz. SIM868 features GPRS multi-slot class 12/class 10 (optional) and supports

the GPRS coding schemes CS-1, CS-2, CS-3 and CS-4. The GNSS solution offers best-in-class acquisition and

tracing sensitivity, Time-To-First-Fix (TTFF) and accuracy.

With a tiny configuration of 17.6*15.7*2.3mm, SIM868 can meet almost all the space requirements in

customers’ applications, such as smart phone, PDA and other mobile devices.

SIM868 is a SMT+LGA package with 77 pads, and provides all hardware interfaces between the module and

customers’ boards.

 One 3 lines serial port and one full modem serial port;

 USB interface which can be used for debugging and upgrading firmware;

 Audio channels which include a microphone input and two speakers output;

 Programmable general purpose input and output;

 Two SIM cards interface;

 Support GNSS function;

 SD card interface;

 I2C interface;

 ADC interface.

SIM868 is designed with power saving technique so that the current consumption is as low as 0.65 mA in sleep

mode (with GNSS engine powered down).

SIM868 integrates TCP/IP protocol and extended TCP/IP AT commands which are very useful for data transfer

applications. For details about TCP/IP applications, please refer to document [2].

2.1. SIM868

Table 1: Module Information

Information SIM868

GSM 850,900,1800 and 1900MHz

GNSS GNSS interface

FLASH 32Mbit

RAM 32Mbit

2.2. SIM868 Key Features

Table 2: SIM868 Key Features

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Feature Implementation

Power supply 3.4V ~4.2V

Power saving Typical power consumption in sleep mode is 0.65 mA (AT+CFUN=0 )

 Quad-band: GSM 850, EGSM 900, DCS 1800, PCS 1900. SIM868 can search

Frequency bands

the 4 frequency bands automatically. The frequency bands can also be set by

AT command “AT+CBAND”. For details, please refer to document [1].

 Compliant to GSM Phase 2/2+

Transmitting power

GPRS connectivity

Temperature range

 Class 4 (2W) at GSM 850 and EGSM 900

 Class 1 (1W) at DCS 1800 and PCS 1900

 GPRS multi-slot class 12（default）

 GPRS multi-slot class 1~12 (option)

 Normal operation: -40°C ~ +85°C

 Storage temperature -45°C ~ +90°C

 GPRS data downlink transfer: max. 85.6 kbps

 GPRS data uplink transfer: max. 85.6 kbps

Data GPRS

 Coding scheme: CS-1, CS-2, CS-3 and CS-4

 PAP protocol for PPP connect

 Integrate the TCP/IP protocol.

 Support Packet Broadcast Control Channel (PBCCH)

USSD  Unstructured Supplementary Services Data (USSD) support

SMS

 MT, MO, CB, Text and PDU mode

 SMS storage: SIM card

SIM interface Support SIM card: 1.8V, 3V

External antenna Antenna pad

Speech codec modes:

 Half Rate (ETS 06.20)

 Full Rate (ETS 06.10)

Audio features

 Enhanced Full Rate (ETS 06.50 / 06.60 / 06.80)

 Adaptive multi rate (AMR)

 Echo Cancellation

 Noise Suppression

Serial port:

 Default one Full modem serial port

 Can be used for AT commands or data stream

Serial port and

USB port

 Support RTS/CTS hardware handshake and software ON/OFF flow control

 Multiplex ability according to GSM 07.10 Multiplexer Protocol

 Autobauding supports baud rate from 1200 bps to 115200bps

 upgrading firmware

USB port:

 Can be used for debugging and upgrading firmware

Phonebook management Support phonebook types: SM, FD, LD, RC, ON, MC

SIM application toolkit GSM 11.14 Release 99

Physical characteristics

 Size:17.6*15.7*2.3mm

 Weight:1.5g

Firmware upgrade Full modern serial port or USB interface (recommend to use USB port)

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Acceleration Accuracy

Table 3: GNSS engine Performance

Parameter Description

Performance

Min Type Max Unit

Horizontal Position

Accuracy

(1)

Velocity Accuracy

(2)

Autonomous <2.5 m

Without Aid 0.1 m/s

DGPS 0.05 m/s

Without Aid 0.1 m/s2

DGPS 0.05 m/s2

Timing Accuracy 10 nS

Backup batter voltage V_BACKUP 2.3 4.3 V

Maximum Altitude 18000 m

Dynamic Performance

Maximum Velocity 515 m/s

Maximum Acceleration

4 G

Hot start 0.7 s

TTFF with GPS

(3)

only

Warm start 21.4 s

Cold start 22.3 s

Hot start 0.7 s

TTFF with

GLONASS only

(3)

Warm start 21.2 s

Cold start 21.68 s

TTFF with GPS and

GLONASS

(3)

A-GPS TTFF(EPO in

flash mode)

Sensitivity with GPS

only mode

Sensitivity with

GLONASS only mode

Sensitivity with GPS

and GLONASS

Hot start 0.6 s

Warm start 21.54 s

Cold start 21.67 s

Hot start 0.6 s

Warm start 21.32 s

Cold start 22.17 s

Autonomous

acquisition(cold start)

-148

dBm

Re-acquisition -158 dBm

Tracking -166 dBm

Autonomous

acquisition(cold start)

-147

dBm

Re-acquisition -155 dBm

Tracking -160 dBm

Autonomous

acquisition(cold start)

-149

dBm

Re-acquisition -157 dBm

Receiver

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Tracking -162 dBm

Channels 22/66

Update rate 5 Hz

Tracking L1, CA Code

Protocol support

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NMEA

Power consumption

With GPS only

(4)

mode

Power consumption

With GLONASS only

(4)

mode

Power consumption

With GPS and

GLONASS

(4)

Acquisition 23.4 mA

Continuous tracking 22.6 mA

Sleep current 650 uA

Acquisition 24 mA

Continuous tracking 21 mA

Sleep current 650 uA

Acquisition 31 mA

Continuous tracking 26 mA

Sleep current 650 uA

(1) 50% 24hr static, -130dBm

(2) 50% at 30m/s

(3) GPS signal level: -130dBm

(4) Single Power supply 3.8V@-130dBm,GSM IDLE

Table 4: Coding schemes and maximum net data rates over air interface

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

2.3. Operating Mode

The table below summarizes the various operating modes of SIM868.

Table 5: Overview of operating modes

Mode Function

Module will automatically go into sleep mode if the conditions of sleep

mode are enabling and there aren’t on air and hardware interrupt (such as

GSM/GPRS

SLEEP

GPIO interrupt or data on serial port).

In this case, the current consumption of module will reduce to the minimal

level.

In sleep mode, the module can still receive paging message and SMS.

Software is active. Module is registered to the GSM network, and the

module is ready to communicate.

Connection between two subscribers is in progress. In this case, the power

consumption depends on network settings such as DTX off/on,

Normal

operation

GSM IDLE

GSM TALK

FR/EFR/HR, hopping sequences, antenna.

GPRS

STANDBY

Module is ready for GPRS data transfer, but no data is currently sent or

received. In this case, power consumption depends on network settings and

GPRS configuration.

GPRS DATA There is GPRS data transfer (PPP or TCP or UDP) in progress. In this case,

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power consumption is related with network settings (e.g. power control

level); uplink/downlink data rates and GPRS configuration (e.g. used

multi-slot settings).

Normal power off by sending AT command “AT+CPOWD=1” or using the PWRKEY. The

Power off

power management unit shuts down the power supply for the baseband part of the module.

Software is not active. The serial port is not accessible. Power supply (connected to 3V)

remains applied.

AT command “AT+CFUN” can be used to set the module to a minimum functionality mode

Minimum

functionality

mode

without removing the power supply. In this mode, the RF part of the module will not work

or the SIM card will not be accessible, or both RF part and SIM card will be closed, and the

serial port is still accessible. The power consumption in this mode is lower than normal

mode.

2.4. Functional Diagram

The following figure shows a functional diagram of SIM868:

 GSM baseband

 PMU

 The GSM Radio Frequency part

 Antenna interface

 GNSS interface

 Other interface

Figure 1: SIM868 functional diagram

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3. Package Information

3.1. Pin Out Diagram

Figure 2: Pin out Diagram (Top view)

3.2. Pin Description

Table 6: Pin description

Pin name Pin number I/O Description Comment

Power supply

GPS_VBAT 34 I Power supply for GNSS

VBAT 35 I Power supply for GSM

VDD_EXT 40 O 2.8V power output

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If these pins are unused,

keep open.

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8,13,19,21,27,30,

GND

31,33,36,37,45,63,

66,67,69,70,71,72,

73,74,75,76,77

Power on/down

PWRKEY 39 I

Audio interfaces

Ground

PWRKEY should be pulled low

and then released to power

on/down the module.

GND for VBAT recommend

to use 36,37pin

Internally pulled up to 3V.

MICP 9

I Differential audio input

MICN 10

SPK1P 11

SPK1N 12

O Differential audio output

SPK2P 44

SPK2N 43

GNSS interface

GPS_RXD 62 I Receive data

GPS_TXD 61 O Transmit data

1PPS 60 O

Time Mark outputs timing pulse

related to receiver time

GPS_EN 59 I GNSS power enable

VRTC 28 I/O Power supply for GNSS RTC

SD interface

MCCA3 46

MCCA2

47

I/O

I/O

SD serial data I/O

MCCA1

MCCA0

48

49

I/O

I/O

If these pins are unused,

keep open.

If these pins are unused,

keep open.

It is recommended to

connect with a battery.

If these pins are unused,

keep open.

MCCK 50

MCCM0 51

I/O

SD serial clock

I/O

SD command output

GPIO

NETLIGHT 41 O Network status

STATUS 42 O Power on status

GPIO1 57 I/O

GPIO2 58 I/O

Programmable general purpose

input and output.

If these pins are unused,

keep open.

Serial port

UART1_DTR 6 I Data terminal ready

UART1_RI 7 O Ring indicator

UART1_DCD 5 O Data carrier detect

UART1_CTS 4 O Clear to send

If these pins are unused,

keep open.

UART1_RTS 3 I Request to send

UART1_TXD 1 O Transmit data

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UART1_RXD 2 I Receive data

UART2_TXD 22 O Transmit data

UART2_RXD 23 I Receive data

Debug interface

USB_VBUS 24 I

USB_DP 25 I/O

Debug and download

USB_DM 26 I/O

ADC

If these pins are unused,

keep open.

ADC 38 I

10bit general analog to digital

converter

I2C

SDA 64 I/O I2C serial bus data

SCL 65 O I2C serial bus clock

SIM card interface

SIM1_VDD 18 O

Voltage supply for SIM card.

Support 1.8V or 3V SIM card

SIM1_DATA 15 I/O SIM data input/output

SIM1_CLK 16 O SIM clock

SIM1_RST 17 O SIM reset

SIM1_DET 14 I SIM card detection

SIM2_VDD 56 O

Voltage supply for SIM card.

Support 1.8V or 3V SIM card

SIM2_DATA 53 I/O SIM data input/output

SIM2_CLK 54 O SIM clock

SIM2_RST 55 O SIM reset

If these pins are unused,

keep open.

Internal pulled up to 2.8V

via 4.7KΩ

All signals of SIM interface

should be protected against

ESD with a TVS diode

array.

If these pins are unused,

keep open.

All signals of SIM interface

should be protected against

ESD with a TVS diode

array.

SIM2_DET 52 I SIM card detection

Antenna interface

GSM_ANT 32 I/O Connect GSM antenna

NC 20 I/O Connect Bluetooth antenna

GPS_ANT 68 I Connect GNSS antenna

Synchronizing signal of RF

RF_SYNC 29 O Synchronizing signal of RF

If these pins are unused,

keep open.

If these pins are unused,

keep open.

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3.3. Package Dimensions

Figure 3: Dimensions of SIM868 (Unit: mm)

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Figure 4: Recommended PCB footprint outline (Unit: mm)

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4. Application Interface

4.1. Power Supply

The power supply range of SIM868 is from 3.4V to 4.2V. Recommended voltage is 4.0V. The transmitting burst

will cause voltage drop and the power supply must be able to provide sufficient current up to 2A. For the VBAT

/GPS_VBAT input, a bypass capacitor (low ESR) such as a 100 µF is strongly recommended.

For the VBAT/GPS_VBAT input, a 100uF Tantalum capacitor (CA low ESR) and a 1uF~10uF Ceramics

capacitor CB are strongly recommended. Increase the 33pF and 10pF capacitors can effectively eliminate the

high frequency interference. A 5.1V/500mW Zener diode is strongly recommended, the diode can prevent chip

from damaging by the voltage surge. These capacitors and Zener diode should be placed as close as possible to

SIM868 VBAT pins.

Figure 5: Reference circuit of the VBAT/GPS_VBAT input

Table 7: Recommended zener diode

Vendor Part number Power(watts) Packages

1 On semi MMSZ5231BT1G 500mW SOD123

2 Prisemi PZ3D4V2H 500mW SOD323

3 Vishay MMSZ4689-V 500mW SOD123

4 Crownpo CDZ55C5V1SM 500mW 0805

The following figure is the reference design of +5V input power supply. The output power supply is 4.1V, thus a

linear regulator can be used.

Figure 6: Reference circuit of the LDO power supply

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VBAT

If there is a high drop-out between the input and the desired output (VBAT), a DC-DC power supply will be

preferable because of its better efficiency especially with the 2A peak current in burst mode of the module. The

following figure is the reference circuit.

Figure 7: Reference circuit of the DC-DC power supply

The single 3.7V Li-ion cell battery can be connected to SIM868 VBAT/GPS_VBAT pins directly. But the Ni-Cd

or Ni-MH battery must be used carefully, since their maximum voltage can rise over the absolute maximum

voltage of the module and damage it.

When battery is used, the total impedance between battery and VBAT/GPS_VBAT pins should be less than

150mΩ.

The following figure shows the VBAT voltage drop at the maximum power transmit phase, and the test condition

is as following:

VBAT=4.0V,

A VBAT bypass capacitor CA=100µF tantalum capacitor (ESR=0.7Ω),

Another VBAT bypass capacitor CB=1uF~10uF.

57 7u s 4.615ms

I

VBA T

VBA T

Burst:2 A

Max:35 0 m V

Figure 8: VBAT voltage drop during transmit burst

4.1.1. Power Supply Pin

Pin34 and Pin35 are GPS_VBAT and VBAT input; Pin36 and Pin37 are GND of power supply. VDD_EXT

output 2.8V when module is in normal operation mode.

When designing the power supply in customers’ application, pay special attention to power losses. Ensure that

the input voltage never drops below 3.0V even when current consumption rises to 2A in the transmit burst. If the

power voltage drops below 3.0V, the module may be shut down automatically. The PCB traces from the VBAT

pins to the power supply must be wide enough (at least 60mil) to decrease voltage drops in the transmit burst.

The power IC and the bypass capacitor should be placed to the module as close as possible.

MIN:3.0V

Figure 9: The minimal VBAT voltage requirement at VBAT drop

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Note: Hardware power off voltage is 3.0V.

4.1.2. Monitoring Power Supply

AT command “AT+CBC” can be used to monitor the VBAT voltage. For detail, please refer to document [1].

4.2. Power on/off SIM868

4.2.1. Power on SIM868

Customer can power on SIM868 by pulling down the PWRKEY pin for at least 1 second and release. This pin is

already pulled up to 3V in the module internal, so external pull up is not necessary. Reference circuits are shown

as below.

3V

100K

Turn on/off

impulse

4.7K

PWRKEY

1K

47K

Power

on/off logic

Module

Figure 10: Powered on/down module using transistor

PWRKEY

Figure 11: Powered on/down module using button

The power on timing is illustrated as in the following figure.

100K

1K

3V

Power

on/off logic

Module

Figure 12: Timing of power on module

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When power on procedure is completed, SIM868 will send following URC to indicate that the module is ready to

operate at fixed baud rate.

RDY

This URC does not appear when autobauding function is active.

Note: Customer can use AT command “AT+IPR=x” to set a fixed baud rate and save the configuration to

non-volatile flash memory. After the configuration is saved as fixed baud rate, the Code “RDY” should be

received from the serial port every time when SIM868 is powered on. For details, please refer to the chapter

“AT+IPR” in document [1].

4.2.2. Power off SIM868

SIM868 will be powered off in the following situations：

 Normal power off procedure: power off SIM868 by the PWRKEY pin.

 Normal power off procedure: power off SIM868 by AT command “AT+CPOWD=1”.

 Abnormal power off: over-voltage or under-voltage automatic power off.

 Abnormal power off: over-temperature or under-temperature automatic power off.

4.2.2.1. Power off SIM868 by the PWRKEY Pin

Customer can power off SIM868 by pulling down the PWRKEY pin for at least 1 second and release. Please refer

to the power on circuit. The power off timing is illustrated in the following figure.

Figure 13: Timing of power off SIM868 by PWRKEY

Note:

1. the module will restart after pull down the pwrkey over 33 seconds.

2. VDD_EXT will power off after STATUS change into low level and the PWRKEY release 55ms..

If 1s<T1<2s，T2>2s；

If 2s≤T1<33s，T2>T1+55ms

This procedure makes the module log off from the network and allows the software to enter into a secure state to

save data before completely shut down.

Before the completion of the power off procedure, the module will send URC:

NORMAL POWER OFF

At this moment, AT commands can’t be executed any more. Power off mode can also be indicated by STATUS pin,

which is at low level at this time.

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4.2.2.2. Power off SIM868 by AT Command

SIM868 can be powered off by AT command “AT+CPOWD=1”. This procedure makes the module log off from

the network and allows the software to enter into a secure state to save data before completely shut down.

Before the completion of the power off procedure, the module will send URC:

NORMAL POWER OFF

At this moment, AT commands can’t be executed any more. Power off mode can also be indicated by STATUS pin,

which is at low level at this time.

For detail about AT command “AT+CPOWD”, please refer to document [1].

4.2.2.3. Over-Temperature or Under-Temperature Power off

The module will constantly monitor the temperature of the module,
If the temperature ≥ +80℃, the following URC will be reported:

+CMTE: 1

If the temperature ≤ -30℃, the following URC will be reported:

+CMTE:-1

If the temperature > +85℃, the following URC will be reported, and the module will be automatically powered

off.

+CMTE: 2

If the temperature < -40℃, the following URC will be reported, and the module will be automatically powered

off.

+CMTE:-2

At this moment, AT commands can’t be executed any more. Power off mode can also be indicated by STATUS

pin, which is at low level at this time.

Note：The default temperature detect is disable, AT command “AT+CMTE” could be used to read the

temperature when the module is running.For details please refer to document [1].

4.2.2.4. Restart SIM868 by PWRKEY Pin:

When the module works normally, if the customer wants to restart the module, follow the procedure below:

1) Power off the module.

2) Wait for at least 800ms after STATUS pin changed to low level.

3) Power on the module.

Figure 14: Timing of restart SIM868

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4.3. Power Saving Mode

SIM868 has two power saving modes: Minimum functionality mode and sleep mode. AT command

“AT+CSCLK=1”can be used to set SIM868 into sleep mode. AT command “AT+CFUN=<fun>“can be used to

set SIM868 into minimum functionality. When SIM868 is in sleep mode and minimum functionality mode, the

current of module is lowest.

4.3.1. Minimum Functionality Mode

There are three functionality modes, which could be set by AT command “AT+CFUN=<fun>“. The command

provides the choice of the functionality levels <fun>=0, 1, 4.

 AT+CFUN=0： Minimum functionality.
 AT+CFUN=1： Full functionality (default).
 AT+CFUN=4： Flight mode (disable RF function).

Table 8: The current consumption of Function Mode

<fun>

BS-PA-MFRMS Current consumption(mA)

0 / 0.65

9 0.86

1

5 1.02

2 1.42

4 / 0.69

Minimum functionality mode minimizes the current consumption to the lowest level. If SIM868 is set to

minimum functionality by “AT+CFUN=0”, the RF function and SIM card function will be disabled. In this

case, the serial port is still accessible, but partial AT commands and correlative to RF function and SIM card

function will not be accessible.

For detailed information about AT command “AT+CFUN=<fun>“, please refer to document [1].

4.3.2. Sleep Mode 1 (AT+CSCLK=1)

Customer can control SIM868 module to enter or exit the sleep mode (AT+CSCLK=1) by DTR signal. When

DTR is in high level and without interrupt (on air and hardware such as GPIO interrupt or data in serial port),

SIM868 will enter sleep mode automatically. In this mode, SIM868 can still receive paging or SMS from

network but the serial port is not accessible.

4.3.3. Wake Up SIM868 from Sleep Mode 1

When SIM868 is in sleep mode 1(AT+CSCLK=1), the following methods can wake up the module:

 Pull down DTR pin.

The serial port will be active after DTR pin is pulled to low level for about 50ms.

 Receive a voice or data call from network.

 Receive a SMS from network.

 Receive external interrupt.

Note: After module has received incoming call or new SMS, serial port can report URC, but the serial port can

not input AT command. Only after the DTR pin is pulled to low level for 50ms, the serial port can input AT

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command.

4.3.4. Sleep Mode 2 (AT+CSCLK=2)

In this mode, SIM868 will continuously monitor the serial port data signal. When there is no data transfer over 5

seconds on the RXD signal and there is no on air and hardware interrupts (such as GPIO interrupt), SIM868 will

enter sleep mode 2 automatically. In this mode, SIM868 can still receive paging or SMS from network.

4.3.5. Wake Up SIM868 from Sleep Mode 2

When SIM868 is in sleep mode 2 (AT+CSCLK=2), the following methods can wake up the module:

 Send data to SIM868 via main serial port (the first character will lose).

 Receive a voice or data call from network.

 Receive a SMS from network.

Note: Autobauding is default. It cannot enter sleep mode in the absence of synchronous serial port baud rate

after module power on.

4.4. Power Saving Mode

Current input for GNSS RTC when the GPS_VBAT is not supplied for the GNSS power system. Current output

for backup battery when the GPS_VBAT power supply is in present and the backup battery is in low voltage

state. The RTC power supply of GNSS can be provided by an external capacitor or a battery (non-chargeable or

rechargeable) through the VRTC. The following figures show various reference circuits for RTC back up.

 External capacitor backup

Figure 15: RTC supply from capacitor

 Non-chargeable battery backup

Figure 16: RTC supply from non-chargeable battery

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 Rechargeable battery backup

Figure 17: RTC supply from rechargeable battery

4.5. Serial Port and USB Interface

SIM868 default provides one unbalanced asynchronous serial ports. The module is designed as a DCE (Data

Communication Equipment). The following figure shows the connection between module and client (DTE).

Table 9: Serial port and USB pin definition

Pin name Pin number Function

UART1_DTR 6 Data terminal ready

UART1_RI 7 Ring indicator

UART1_DCD 5 Data carrier detect

UART1_CTS 4 Clear to send

UART1_RTS 3 Request to send

Serial port

UART1_TXD 1 Transmit data

UART1_RXD 2 Receive data

UART2_TXD 22 Transmit data

UART2_RXD 23 Receive data

GPS_TXD 61 Transmit data

GPS_RXD 62 Receive data

USB_VBUS 24 USB power supply

Debug port

USB_DP 25 D+ data input/output

USB_DM 26 D- data input/output

Note: Hardware flow control is disabled by default. AT command “AT+IFC=2, 2”can enable hardware flow

control. AT command “AT+IFC=0,0”can disable hardware flow control. For more details please refer to

document [1].

Table 10: Serial port characteristics

Symbol Min Max Unit

VIL -0.3 0.7 V

VIH 2.1 3.1 V

VOL - 0.4 V

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VOH 2.4 - V

4.5.1 Function of Serial Port

Serial port:

 Full mode device.

 Contain data lines UART1_TXD/UART1_RXD, hardware flow control lines UART1_RTS/UART1_CTS,

status lines UART1_DTR、UART1_DCD and UART1_RI.

 Serial port can be used for GPRS service and AT communication. It can also be used for multiplexing

function. For details about multiplexing function, please refer to table 11.

 Autobauding supports the following baud rates:

1200, 2400, 4800, 9600, 19200, 38400, 57600 and 115200bps

Autobauding allows SIM868 to automatically detect the baud rate of the host device. Pay more attention to the

following requirements:

 Synchronization between DTE and DCE:

When DCE powers on with autobauding enabled, it is recommended to send "AT" or "at" or "aT" or "At"

to synchronize the baud rate, until DTE receives the "OK" response, which means DTE and DCE are

correctly synchronized. For more information please refer to AT command "AT+IPR".

 Restrictions of autobauding operation:

The DTE serial port must be set at 8 data bits, no parity and 1 stop bit.

The URC such as "RDY", "+CFUN: 1" and "+CPIN: READY” will not be reported.

Note: Customer can use AT command “AT+IPR=x” to set a fixed baud rate and the setting will be saved to

non-volatile flash memory automatically. After the configuration is set as fixed baud rate, the URC such as

"RDY", "+CFUN: 1" and "+CPIN: READY” will be reported when SIM868 is powered on.

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4.5.2 Serial Interfaces

The following figure shows the connection between module and client (DTE).

Module(DCE)

Serial Port

UART1_TXD

UART1_RXD

UART1_RTS

UART1_CTS

UART1_DTR

UART1_DCD

UART1_RI

GND GND

Customer(DTE)

Serial Port

TXD

RXD

RTS

CTS

DTR

DCD

RING

Figure 18: Connection of the serial interfaces

If the voltage of UART is 3.3V, the following reference circuits are recommended. If the voltage is 3.0V, please

change the resistors in the following figure from 5.6K to 14K.

UART1_TXD

UART1_RXD

UART1_RTS

UART1_CTS

UART1_DTR

UART1_DCD

UART1_RI

GND

1K

1K

1K

1K

1K

1K

1K

5.6K

5.6K5.6K

RXD

TXD

RTS

CTS

GPIO

GPIO

EINT

GND

Module

(3.3V)

Figure 19: Resistor matching circuit

If the voltage of UART is 3V or3.3V, the following reference circuits are recommended:

DTE

VDD_EXT

UART1_TXD

GND

10K

TXDUART1_RXD

RXD

10K

GND

Module DTE

Figure 20 : Diode isolation circuit

Note: please make sure the minimum of client high limit should be less than 2.8V minus the diode drop.

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VDD

_

EXT

If the voltage of UART is 5V, the following reference circuits are recommended:

VDD_EXT

Module

VDD_EXT

UART1_TXD

Figure 21: TX level matching circuit

Module

VDD_EXT

UART1_RXD

47K

4.7K

4.7K

4.7K

DTE

VDD

4.7K

RXD

DTE

VDD

47K

TXD

Figure 22: RX level matching circuit

4.5.3 Debug Interface

SIM868 could achieve software debug function through USB interface. When powering on the module, connect

USB_VBUS, USB_DP, USB_DM, and GND to PC, then install the driver following the prompts, a UART port

could be recognized by PC, customer could achieve the software Debug with this UART port.

SIMCom recommended the following connected diagram:

USB_VBUS

22R

USB_DM

22R

USB_DP

1uF

GND

VBUS

USB_DM

USB_DP

GND

MODULE

USB

Figure 23: USB reference circuit

The TVS on USB data line should be less than 5pF, and traced by differential forms.

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Note: please reserve the USB interface or test point for the further debugging

Table 11: USB_VBUS operation voltage

Pin Min Typ Max Unit

USB_VBUS 4.3 5.0 7.0 V

4.5.4 Software Upgrade

Customer could upgrade module’s firmware through USB or UART interface.

If upgrading through USB interface, it is necessary to power on SIM868 first, and then connect USB_VBUS,

USB_DP, USB_DM, and GND to PC. There is no need to operate PWRKEY pin in the whole procedure, when

SIM868 detects USB_VBUS and could communicate normally with USB_DP and USB_DM, it will enter USB

download mode automatically.

If customer upgrades the software through UART interface, it is strongly recommended to lead the UART1_TXD,

UART1_RXD, GND and PWRKEY pin to IO connector for the upgrading, and PWRKEY pin should connect to

GND while upgrading. Refer to the following figure for debugging and upgrading software.

Module(DCE)

Serial Port

UART1_TXD

UART1_RXD

GND

PWRKEY

I/O Connector

TXD

RXD

GND

PWRKEY

Figure 24: Connection for software upgrading and debugging

The UART interface supports the CMOS level. If customer connects the module to the computer, the level shifter

should be added between the DCE and DTE.

4.6. UART1_RI Behaviors

Table 12: RI behaviors

State RI response

Standby High

The pin is changed to low. When any of the following events occur, the pin will be changed to

Voice call

high:

（1）Establish the call
（2）Hang up the call

SMS

The pin is changed to low, and kept low for 120ms when a SMS is received. Then it is changed

to high.

Others For more details, please refer to document [2].

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The behavior of the RI pin is shown in the following figure when the module is used as a receiver.

HIGH

LOW

RI

Establish the call

Hang up the call

Idle Ring

Figure 25: UART1_RI behaviour of voice calling as a receiver

HIGH

LOW

RI

120ms

Idle

Receive SMS
URC

Figure 26: UART1_RI behaviour of URC or receive SMS

However, if the module is used as caller, the UART1_RI will remain high. Please refer to the following figure.

RI

HIGH

LOW

Idle

Ring

Establish

the call

Hang up

the call

Idle

Figure 27: UART1_RI behaviour as a caller

4.7. Audio Interfaces

SIM868 provides an analog input (MICP; MICN), which could be used for electret microphone. The module also

provides two analog outputs (SPK1P/2P; SPK1N/2N).

Table 13: Audio interface definition

Pin name Pin number Function

MICP 9 Audio input positive

MICN 10 Audio input negative

SPK1P 11 Audio output positive

SPK1N 12 Audio output negative

SPK2P 44 Audio output positive

SPK2N 43 Audio output negative

SPK1P/1N output can directly drive 32Ω receiver.

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SIM868 internal has class-AB audio amplifier, the following table is class-AB performance:

Table 14: Performance of audio amplifier

Test Conditions Class-AB AMP

4.2V 8Ω THD+N=1% 0.87W

3.3V 8Ω THD+N=1% 0.53W

4.2V 8Ω THD+N=10% 1.08W

3.3V 8Ω THD+N=10% 0.65W

SPK2P/2N output can directly drive 8Ω speaker.

AT command “AT+CMIC” is used to adjust the input gain level of microphone. AT command “AT+SIDET”

is used to set the side-tone level. In addition, AT command “AT+CLVL” is used to adjust the output gain level.

For more details, please refer to document [1].

In order to improve audio performance, the following reference circuits are recommended. The audio signals

have to be layout according to differential signal layout rules as shown in following figures.

4.7.1. Speaker Interfaces Configuration

SPK1P/2P

SPK1N/2N

Module

10pF

10pF

10pF

33pF

33pF

33pF

Figure 28: Speaker reference circuit

Close to speaker

10pF

10pF

10pF

33pF

33pF

33pF

ESD

ESD

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4.7.2. Microphone Interfaces Configuration

These components should

be placed to microphone

as close as possible

ESD

ESD

Electret

Microphone

MICP

MICN

The lines in bold type should

be accorded to differential

signal layout rules

10pF

10pF

10pF

33pF

33pF

33pF

Module

Figure 29: Microphone reference circuit

4.7.3. Audio Electronic Characteristic

Table 15: Microphone input characteristics

Parameter Min Typ Max Unit

Microphone biasing voltage - 1.9 2.2 V

Working current - - 2.0 mA

Input impedance(differential) 13 20 27 KΩ

Idle channel noise - - -67 dBm0

Input level:-40dBm0 29 - - dB

SINAD

Input level:0dBm0 - 69 - dB

Table 16: Audio output characteristics

Parameter Conditions Min Typ Max Unit

RL=32 Ω receiver - 15 90 mW

Normal output

RL=8 Ω speaker - - 1080 mW

4.7.4. TDD

Audio signal could be interferenced by RF signal. Coupling noise could be filtered by adding 33pF and 10pF

capacitor to audio lines. 33pF capacitor could eliminate noise from GSM850/EGSM900MHz, while 10pF

capacitor could eliminate noise from DCS1800/PCS1900Mhz frequency. Customer should develop this filter

solution according to field test result.

GSM antenna is the key coupling interfering source of TDD noise. Thereat, pay attention to the layout of audio

lines which should be far away from RF cable, antenna and VBAT pin. The bypass capacitor for filtering should

be placed near module and another group needs to be placed near to connector.

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Conducting noise is mainly caused by the VBAT drop. If audio PA was powered by VBAT directly, then there

will be some cheep noise from speaker output easily. So it is better to put big capacitors and ferrite beads near

audio PA input.

TDD noise has something to do with GND signal. If GND plane is not good, lots of high-frequency noises will

interference microphone and speaker over bypass capacitor. So a good GND during PCB layout could avoid

TDD noise.

4.8. SIM Card Interface

The SIM interface complies with the GSM Phase 1 specification and the new GSM Phase 2+ specification for

FAST 64kbps SIM card. Both 1.8V and 3.0V SIM card are supported. The SIM interface is powered from an

internal regulator in the module.

4.8.1. SIM Card Application

Table 17: SIM pin definition

Pin name

Pin number Function

SIM1_VDD 18 Voltage supply for SIM card. Support 1.8V or 3V SIM card

SIM1_DATA 15 SIM data input/output

SIM1_CLK 16 SIM clock

SIM1_RST 17 SIM reset

SIM1_DET 14 SIM card detection

SIM2_VDD 56 Voltage supply for SIM card. Support 1.8V or 3V SIM card

SIM2_DATA 53 SIM data input/output

SIM2_CLK 54 SIM clock

SIM2_RST 55 SIM reset

SIM2_DET 52 SIM card detection

It is recommended to use an ESD protection component such as ST (www.st.com ) ESDA6V1-5W6 or ON

SEMI (www.onsemi.com ) SMF05C. The SIM card peripheral components should be placed close to the SIM

card holder. The reference circuit of the 8-pin SIM card holder is illustrated in the following figure.

Module

VDD_EXT

SIM_VDD

SIM_RST
SIM_CLK
SIM_DET

SIM_DATA

4.7K

22pF

22pF

22pF

51O
51O

51O

100nF

MOLEX-91228

VCC
RST
CLK I/O
PRESENCE

ESDA6V1

GND
VPP

GND

SIM Card

Figure 30: Reference circuit of the 8-pin SIM card holder

The SIM_DET pin is used for detection of the SIM card hot plug in. Customer can select the 8-pin SIM card

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holder to implement SIM card detection function. AT command “AT+CSDT” is used to enable or disable SIM

card detection function. For details of this AT command, please refer to document [1].

If the SIM card detection function is not used, customer can keep the SIM_DET pin open. The reference circuit

of 6-pin SIM card holder is illustrated in the following figure.

MOLEX-91228

VCC
RST
CLK I/O

C107 10M 006 512

ESDA6V1

GND
VPP

Module

SIM_VDD

SIM_RST
SIM_CLK
SIM_DET

SIM_DATA

22pF

22pF

22pF

51O
51O

51O

100nF

Figure 31: Reference circuit of the 6-pin SIM card holder

4.8.2. SIM Card Design Guide

SIM card signal could be interferenced by some high frequency signal, it is strongly recommended to follow

these guidelines while designing:

 SIM card holder should be far away from GSM antenna

 SIM traces should keep away from RF lines, VBAT and high-speed signal lines

 The traces should be as short as possible

 Keep SIM card holder’s GND connect to main ground directly

 Shielding the SIM card signal by ground well

 Recommended to place a 100nF capacitor on SIM_VDD line and keep close to the SIM card holder

 Add some TVS which parasitic capacitance should not exceed 50pF

 Add 51Ω resistor to (SIM_RST/SIM_CLK/SIM_DATA) signal could enhance ESD protection

 Add 22pf capacitors to (SIM_RST/SIM_CLK/SIM_DATA) signal to reduce RF interference

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4.8.3. Design Considerations for SIM Card Holder

For 8 pins SIM card holder, SIMCom recommends to use Molex 91228.Customer can visit

http://www.molex.com for more information about the holder.

Figure 32: Molex 91228 SIM card holder

Table 18: Pin description (Molex SIM card holder)

Pin name Signal Description

C1 SIM_VDD SIM card power supply

C2 SIM_RST SIM card reset

C3 SIM_CLK SIM card clock

C4 GND Connect to GND

C5 GND Connect to GND

C6 VPP Not connect

C7 SIM_DATA SIM card data I/O

C8 SIM_DET Detect SIM card presence

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For 6-pin SIM card holder, SIMCom recommends to use Amphenol C707 10M006 512 .Customer can visit

http://www.amphenol.com for more information about the holder.

Figure 33: Amphenol C707 10M006 512 SIM card holder

Table 19: Pin description (Amphenol SIM card holder)

Pin name Signal Description

C1 SIM_VDD SIM card power supply

C2 SIM_RST SIM card reset

C3 SIM_CLK SIM card clock

C5 GND Connect to GND

C6 VPP Not connect

C7 SIM_DATA SIM card data I/O

Note: Every time plug SIM card interval advice is greater than 2s. Otherwise may not be able to correct

detection.

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4.9. SD Interface

SD interface can be configured as PCM interface; the following table shows the detailed multiplexing function.

Table 20: SD multiplexing function

Pin name Pin number Mode 0(default) Mode 1 Mode 2 Mode 3

MCCA3 46 MCCA3 DAIPCMOUT(1.8V) GPIO EINT19

MCCA2 47 MCCA2 DAICLK(1.8v) GPIO EINT18

MCCA1 48 MCCA1 DAIPCMIN(1.8v) GPIO EINT17

MCCA0 49 MCCA0 DAISYNC (1.8v) GPIO

MCCK 50 MCCK GPIO

MCCM0 51 MCCM0 GPIO

Note: Customer can use AT command set mode. For detail, please refer to document [1].

SIM868 provides a hardware SD interface:

Figure 34: SD reference circuit

If power supply is 2.8V for SD card, customer can use VDD_EXT; if power supply is 3.3V, please use external

design LDO.

4.10. I2C Bus

The SIM868 provides an I2C interface which is only used in the embedded AT application.

Table 21: Pin definition of the I2C

Pin name Pin number Description

SCL 65 I2C serial bus clock(open drain output)

SDA 64 I2C serial bus data(open drain output)

Note:

1. I2C should be pulled up to 2.8V via 4.7K externally.

2. I2C function is not supported in the standard firmware. If you need, please contact SIMCom.

4.10.1. I2C Multiplexing Function

Table 22: I2C multiplexing function

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Status

SIM868

behavior

Off Powered off

64ms On/ 800ms Off

Not registered the network

64ms On/ 3000ms Off

Registered to

the network

64ms On/ 300ms Off

GPRS communication is established

NETLIGHT

41

Network Status Indication

Pin name Pin number Mode 0(default) Mode 1

SCL 65 SCL GPIO

SDA 64 SDA GPIO

Note: Customer can use AT command set mode. For detail, please refer to document t[1].

4.11. ADC

Table 23: Pin definition of the ADC

Pin name Pin number Description

ADC 38 Analog voltage input

SIM868 provides an auxiliary ADC, which can be used to measure the voltage. Customer can use AT command

“AT+CADC” to read the voltage value.

Note: Customer can use AT command set mode. For detail, please refer to document t[1].

Table 24: ADC specification

Parameter Min Typ Max Unit

Voltage range 0 - 2.8 V

ADC Resolution - 10 - bits

RIN

CIN

Input resistance

Unselected channel

Selected channel

Input capacitance

Unselected channel

Selected channel

400

1

50

4

M

M

fF

pF

Sampling rate - - 1.08 MHz

ADC precision 10 30 mV

4.12. Network Status Indication

Table 25: Pin definition of the NETLIGHT

Pin name Pin number Description

The NETLIGHT pin can be used to drive a network status indication LED. The status of this pin is listed in

following table:

Table 26: Status of the NETLIGHT pin

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Reference circuit is recommended in the following figure:

Module

VBAT

R

NETLIGHT

4.7K

47K

Figure 35: Reference circuit of NETLIGHT

Table 27: NETLIGHT multiplexing function

Pin name Pin number Mode 0(default) Mode 1

NETLIGHT 41 NETLIGHT GPIO

Note: Customer can use AT command set mode. For detail, please refer to document t[1].

4.13. Operating Status Indication

The pin42 is for operating status indication of the module. The pin output is high when module is powered on,

and output is low when module is powered off.

Table 28: Pin definition of the STATUS

Pin name Pin number Description

STATUS 42 Operating status indication

Note: For timing about STATUS, please reference to the chapter “4.2 power on/down scenarios”

4.14. RF Synchronization Signal

The synchronization signal serves to indicate growing power consumption during the transmit burst.

Table 29: Definition of the RF_SYNC pin

Pin name Pin number Description

RF_SYNC 29 Transmit synchronization signal

The timing of the synchronization signal is shown in the following figure. High level of the RF_SYNC signal

indicates increased power consumption during transmission.

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220us

577us

Transmit burst

RF_SYNC

Figure 36: RF_SYNC signal during transmit burst

4.14.1. RF_SYNC Multiplexing Function

RF_SYNC can also be used as GPIO to indicate the RF Jamming. The RF_SYNC function and RF Jamming

Detection function can be switched by AT+SJDR command.

Table 30: RF_SYNC Multiplexing function

Pin name Pin number Mode 0(default) Mode 1

RF_SYNC 29 RF Synchronization Signal JD（RF jamming detection）

Note: About AT+SJDR, please refer to document [1].

4.15. GNSS

4.15.1. GNSS Overview

SIM868 provide a high-performance L1 GNSS solution for cellular handset applications. The solution offers

best-in-class acquisition and tracking sensitivity, Time-To-First-Fix (TTFF) and accuracy. The GNSS engine

supports both fully-autonomous operations for use in handheld consumer navigation devices and other

standalone navigation systems.

GNSS engine Performance, please refer to Table 3.

GNSS NMEA information is output by serial port. The default baud rate is 115200bps.

4.15.2. Power on/down GNSS

The GNSS engine is controlled by GNSS_EN PIN, so when it is necessary to run GNSS，the GNSS_EN must be
pulled up to 2.8V. When it is necessary to power off GNSS，the GNSS_EN must be pulled down to GND.

4.15.3. 1PPS Output

The 1PPS pin outputs pulse-per-second (1PPS) pulse signal for precise timing purposes. It will come out after

successfully positioning .The 1PPS signal can be provided through designated output pin for many external

applications.

4.16. Antenna Interface

There are two antenna interfaces, GSM_ANT、GPS_ANT.

 The input impendence of the two antenna should be 50Ω, and the VSWR should be less than 2.

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 It is recommended that the GSM antenna should be placed as far as possible.

 The isolations of the two antenna should be bigger than 30dB

 The modular connection to the antenna is made through a host’s printed board microstrip trace

layout,the impendence of the microstrip trace is control in 50Ω，the series connection component in the
trace is 0Ω resistors for default, the size of series connection componentcan be 0402 or 0201.the length

of the microstrip trace should be as short as possible for reduce insertion loss.

4.16.1. GSM Antenna Interface

There is a GSM antenna pad named GSM_ANT to connect an external GSM antenna, the connection of the

antenna must be decoupled from DC voltage. This is necessary because the antenna connector is DC coupled to

ground via an inductor for ESD protection. The external antenna must be matched properly to achieve the best

performance, so the matching circuit is necessary.

It is recommended to reserve the matching circuit as following:

Figure 37: GSM antenna matching circuit

The RF connector is used for conduction test. If the space between RF pin and antenna is not enough, the

matching circuit should be designed as in the following figure:

Figure 38: GSM antenna matching circuit without RF connector

In above figure, the components R101, C101 and C102 are used for antenna matching, the value of components
can only be got after the antenna tuning, usually, they are provided by antenna vendor. By default, the R101 is 0Ω

resistors, and the C101, C102 are reserved for tuning.

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Dipole Antenna Reference PCBLayout Requirements.

Dipole Antenna Reference Design PCB

Mount these devices with brown mark facing up. Units: mm

Line width should be designed to provide 50Ωimpedance matching characteristics.

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The RF test connector in the figure is used for the conducted RF performance test, and should be placed as close
as to the module’s antenna pin. The traces impedance between components must be controlled in 50Ω. The

component D101 is a bidirectional TVS component, which is used for ESD protection, the recommended part

numbers of the TVS are listed in the following table:

Table 31: Recommended TVS component

Package Type Supplier

0201 LXES03AAA1-098 Murata

0201 LXES03AAA1-154 Murata

0402 LXES15AAA1-153 Murata

0402 LXES15AAA1-100 Murata

0402 LXES15AAA1-017 Murata

4.16.2. GNSS Antenna Interface

The module also provides a GNSS antenna interface named GPS_ANT to connect the antenna on the customer’s

application board. To obtain excellent GNSS reception performance, a good antenna will always be required.

Proper choice and placement of the antenna will ensure that satellites at all elevations can be seen, and therefore,

accurate fix measurements are obtained. There are two normal options: passive antenna and active antenna.

GNSS antenna choice should be based on the designing product and other conditions. For detailed Antenna

designing consideration, please refer to related antenna vendor’s design recommendation. The antenna vendor will

offer further technical support and tune their antenna characteristic to achieve successful GNSS reception

performance.

SIM868 provides GSM antenna named GSM_ANT, customer could use 50Ω microstrip line or stripline antenna

connect to the module. The maximum gain of the Main antenna gain should not exceed 3dBi considering the

SAR radio. No antenna gain may be used that would exceed the 2W EIRP power limit in 1900MHz band。

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It have according to reference trace and matching circuit testing all FCC items,and all items satisfy FCC

requirements.Only the reference trace and matching circuit is certified, antenna design must refer to it, any

other deviations require testing Class II applications as required by FCC. The certified matching circuit as

following:

The external antenna must be matched properly to achieve best performance, so the matching circuit is necessary,

the connection is recommended as the following figure:

Figure 39: GNSS passive antenna matching circuit

The components R101, C101 and C102 are used for antenna matching, the components’ value only can be got
after the antenna tuning. Normally R101 is 0Ω, C101 and C102 are not mounted.

Figure 40: GNSS active antenna matching circuit

Active antennas have an integrated Low-Noise Amplifier (LNA). VCC_ANT is needed on customer’s application

board for the active antenna power input, as shown in Figure 40. The inductor L101 is used to prevent the RF

signal from leaking into the VCC_ANT pass and route the bias supply to the active antenna, the recommended

value of L101 is no less than 27nH. R102 can protect the whole circuit in case the active antenna is shorted to

ground.

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5. PCB Layout

This section will give some guidelines on PCB layout, in order to eliminate interfere or noise.

5.1 Pin Assignment

Before PCB layout, we should learn about pin assignment in order to get reasonable layout with so many

external components. Following figure is the overview of pin assignment of the module.

Figure 41: PIN assignment

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5.2 Principle of PCB Layout

During layout, attention should be paid to the following interfaces, like Antenna, power supply, SIM card

interface, audio interface, and so on.

5.2.1 Antenna Interface

 The length of trace between pin output and connector should be as short as possible;

 Do not trace RF signal over across the board;

 The RF signal should be far away from SIM card, power ICs.

5.2.2 Power Supply

 VBAT and return GND are very important in layout;

 The positive line of VBAT should be as short and wide as possible;

 The correct flow from source to VBAT pin should go though Zener diode then huge capacitor;

 Pin 36 and Pin37 are GND signals, and shortest layout to GND of power source should be designed;

 There are 23 GND pads in the module; these pads could enhance the GND performances. On the

upper layer of these pads, do not trace any signal if possible.

5.2.3 SIM Card Interface

 SIM card holder has no anti-EMI component inside. Thus SIM card interface maybe interfered,

please pay more attention on this interface during layout;

 Ensure SIM card holder is far way from antenna or RF cable inside;

 Put SIM card holder near the module, as nearer as possible;

 Add ESD component to protect SIM_CLK, SIM_DATA, SIM_RST and SIM_VDD signals which

should be far away from power and high-speed-frequency signal.

5.2.4 Audio Interface

 The signal trace of audio should far away from antenna and power;

 The audio signal should avoid to parallel with VBAT trace.

5.2.5 Others

 It is better to trace signal lines of UART bunched, as well as signals of USB.

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6. Electrical, Reliability and Radio Characteristics

6.1 Absolute Maximum Ratings

The absolute maximum ratings stated in following table are stress ratings under non-operating conditions.

Stresses beyond any of these limits will cause permanent damage to SIM868.

Table 32: Absolute maximum ratings

Symbol Min Typ Max Unit

VBAT - - 4.5 V

Current 0 - 2.0 A

USB_VBUS - - 7 V

II* - 4 16 mA

IO* - 4 16 mA

These parameters are for digital interface pins, GPIO, and UART.

6.2 Recommended Operating Conditions

Table 33: Recommended operating conditions

Symbol Parameter Min Typ Max Unit

VBAT Power supply voltage 3.4 4.0 4.4 V

T

Operating temperature -40 +25 +85 ℃

OPER

T

Storage temperature -45 +90 ℃

STG

6.3 Digital Interface Characteristics

Table 34: Digital interface characteristics

Symbol Parameter Min Typ Max Unit

VIH High-level input voltage 2.1 - 3.1 V

VIL Low-level input voltage -0.3 - 0.7 V

VOH High-level output voltage 2.4 - - V

VOL Low-level output voltage - - 0.4 V

Note: These parameters are for digital interface pins, such as keypad, GPIO and UART.

6.4 SIM Card Interface Characteristics

Table 35: SIM card interface characteristics

Symbol Parameter Min Typ Max Unit

IIH High-level input current -1.0 - 1.0 uA

IIL Low-level input current -1.0 - 1.0 uA

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50

VIH High-level input voltage

1.4 - - V

2.4 - - V

- - 0.27 V

VIL Low-level input voltage

0.4 V

1.62 - - V

VOH High-level output voltage

2.7 - - V

- - 0.36 V

VOL Low-level output voltage

- - 0.4 V

6.5 SIM_VDD Characteristics

Table 36: SIM_VDD characteristics

Symbol Parameter Min Typ Max Unit

- 3.0 -

VO Output voltage

V

- 1.8 -

IO Output current - - 10 mA

6.6 VDD_EXT Characteristics

Table 37: VDD_EXT characteristics

Symbol Parameter Min Typ Max Unit

VO Output voltage 2.7 2.8 2.9 V

IO Output current - - 50 mA

6.7 Current Consumption（VBAT=4.0V）

Table 38: Current consumption

Symbol Parameter Conditions Min Typ Max Unit

Voltage 4.0 V

Power drop PCL=5 350 mV

VBAT

Voltage ripple

I

Average current

VBAT

PCL=5

@ f<200kHz

@ f>200kHzss

2.0

mV

mV

Power off mode 130 150 uA

Sleep mode (AT+CFUN=1)：

( BS-PA-MFRMS=9 )

( BS-PA-MFRMS=5)

( BS-PA-MFRMS=2)

Idle mode (AT+CFUN=1)：

GSM850

EGSM900

DCS1800

0.86

1.02

1.42

13.7

13.7

13.7

mA

mA

mA

mA

mA

mA

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PCS1900 13.7 mA

Voice call (PCL=5)：

GSM850

EGSM900

Voice call (PCL=0)：

DCS1800

PCS1900

Data mode GPRS (1Rx,4Tx)：

GSM850

EGSM900

DCS1800

PCS1900

Data mode GPRS (3Rx,2Tx)：

GSM850

EGSM900

DCS1800

PCS1900

Data mode GPRS (4Rx,1Tx)：

GSM850

EGSM900

DCS1800

PCS1900

223

234

162

170

378

414

270

308

323

340

212

236

217

223

153

163

mA

mA

mA

mA

mA

mA

mA

mA

mA

mA

mA

mA

mA

mA

mA

mA

I

Peak current During Tx burst 2.0 A

MAX

Note: In above table the current consumption value is the typical one of the module tested in laboratory. In

the mass production stage, there may be differences among each individual.

6.8 Electro-Static Discharge

SIM868 is an ESD sensitive component, so attention should be paid to the procedure of handling and packaging.

The ESD test results are shown in the following table.

Table 39: The ESD characteristics (Temperature: 25℃, Humidity: 45 %)

Pin name Contact discharge Air discharge

VBAT ±5KV ±10KV

GND ±5KV ±10KV

UART1_TXD /UART1_RXD ±4KV ±8KV

Antenna port ±5KV ±10KV

SPKP/SPKN/MICP/MICN ±4KV ±8KV

PWRKEY ±4KV ±8KV

6.9 Radio Characteristics

6.9.1 Module RF Output Power

The following table shows the module conducted output power, it is followed by the 3GPP TS 05.05 technical

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specification requirement.

Table 40: GSM850 and EGSM900 conducted RF output power

GSM850,EGSM900

PCL Nominal output power (dBm)

Tolerance (dB) for conditions

Normal Extreme

5 33 ±2 ±2.5

6 31 ±3 ±4

7 29 ±3 ±4

8 27 ±3 ±4

9 25 ±3 ±4

10 23 ±3 ±4

11 21 ±3 ±4

12 19 ±3 ±4

13 17 ±3 ±4

14 15 ±3 ±4

15 13 ±3 ±4

16 11 ±5 ±6

17 9 ±5 ±6

18 7 ±5 ±6

19-31 5 ±5 ±6

Table 41: DCS1800 and PCS1900 conducted RF output power

DCS1800,PCS1900

Tolerance (dB) for conditions

PCL Nominal output power (dBm)

Normal Extreme

0 30 ±2 ±2.5

1 28 ±3 ±4

2 26 ±3 ±4

3 24 ±3 ±4

4 22 ±3 ±4

5 20 ±3 ±4

6 18 ±3 ±4

7 16 ±3 ±4

8 14 ±3 ±4

9 12 ±4 ±5

10 10 ±4 ±5

11 8 ±4 ±5

12 6 ±4 ±5

13 4 ±4 ±5

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14 2 ±5 ±6

15 0 ±5 ±6

For the module’s output power, the following should be noted:

At GSM900 and GSM850 band, the module is a class 4 device, so the module’s output power should not exceed

33dBm, and at the maximum power level, the output power tolerance should not exceed +/-2dB under normal

condition and +/-2.5dB under extreme condition.

At DCS1800 and PCS1900 band, the module is a class 1 device, so the module’s output power should not exceed 30dBm, and at the

maximum power level, the output power tolerance should not exceed +/-2dB under normal condition and +/-2.5dB under extreme

condition.

6.9.2 Module RF Receive Sensitivity

The following table shows the module’s conducted receiving sensitivity, it is tested under static condition.

Table 42: Conducted RF receive sensitivity

Frequency

Receive sensitivity（Typical）

Receive sensitivity(Max)

GSM850,EGSM900 < -109dBm < -107dBm

DCS1800,PCS1900 < -109dBm < -107dBm

6.9.3 Module Operating Frequencies

The following table shows the module’s operating frequency range; it is followed by the 3GPP TS 05.05

technical specification requirement.

Table 43: Operating frequencies

Frequency Receive Transmit

GSM850 869 ～ 894MHz 824 ～ 849MHz

EGSM900 925 ～ 960MHz 880 ～ 915MHz

DCS1800 1805 ～ 1880MHz 1710 ～ 1785MHz

PCS1900 1930 ～ 1990MHz 1850 ～ 1910MHz

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7. Manufacturing

7.1. Top and Bottom View of SIM868

Figure 42: Top and bottom view of SIM868

7.2. Typical Solder Reflow Profile

Figure 43: Typical solder reflow profile of lead-free process

7.3. The Moisture Sensitivity Level

The moisture sensitivity level of SIM868 module is 3. The modules should be mounted within 168 hours after
unpacking in the environmental conditions of temperature <30℃ and relative humidity of <60% (RH). It is

necessary to bake the module if the above conditions are not met:

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Table 44: Moisture sensitivity level and floor life

Moisture Sensitivity Level

Floor Life (out of bag) at factory ambient≤30°C/60% RH or as stated

(MSL)

1 Unlimited at ≦30℃/85% RH

2 1 year

2a 4 weeks

3 168 hours

4 72 hours

5 48 hours

5a 24 hours

6

Mandatory bake before use. After bake, it must be reflowed within the time limit

specified on the label.

NOTES:

1. If the vacuum package is not open for 3 months or longer than the packing date, baking is also

recommended before re-flow soldering.

2. For product handling, storage, processing, IPC / JEDEC J-STD-033 must be followed.

7.4. Baking Requirements

SIM868 modules are vacuum packaged, and guaranteed for 6 months storage without opening or leakage under
the following conditions: the environment temperature is lower than 40℃, and the air humidity is less than 90%.

If the condition meets one of the following ones shown below, the modules should be baked sufficiently before

re-flow soldering, and the baking condition is shown in below table; otherwise the module will be at the risk of

permanent damage during re-flow soldering.

 If the vacuum package is broken or leakage;

 If the vacuum package is opened after 6 months since it’s been packed;
 If the vacuum package is opened within 6 months but out of its Floor Life at factory ambient≦30℃

/60%RH or as stated.

Table 45: Baking requirements

Baking temperature Moisture Time

40℃±5℃ <5% 192 hours

120℃±5℃ <5% 4 hours

Note: Care should be taken if that plastic tray is not heat-resistant, the modules should be taken out for

preheating, otherwise the tray may be damaged by high-temperature heating.

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8. Appendix

I. Related Documents

Table 46: Related documents

SN Document name Remark

[1]

[2]

[3]

[4] GSM 07.07：

SIM800_Series_AT_Command_

Manual

SIM800 Series Port Application

Note_V1 02.doc

ITU-T Draft new
recommendation V.25ter：

Serial asynchronous automatic dialing and control

Digital cellular telecommunications (Phase 2+); AT command set for

GSM Mobile Equipment (ME)

[5] GSM 07.10： Support GSM 07.10 multiplexing protocol

Digital cellular telecommunications (Phase 2+); Use of Data

[6] GSM 07.05：

Terminal Equipment – Data Circuit terminating Equipment (DTE –

DCE) interface for Short Message Service (SMS) and Cell

Broadcast Service (CBS)

Digital cellular telecommunications system (Phase 2+);

[7] GSM 11.14：

Specification of the SIM Application Toolkit for the Subscriber

Identity Module – Mobile Equipment (SIM – ME) interface

Digital cellular telecommunications system (Phase 2+);

[8] GSM 11.11：

Specification of the Subscriber Identity Module – Mobile

Equipment (SIM – ME) interface

[9] GSM 03.38：

Digital cellular telecommunications system (Phase 2+); Alphabets

and language-specific information

Digital cellular telecommunications system (Phase 2)； Mobile

[10] GSM 11.10

Station (MS) conformance specification； Part 1： Conformance

specification

[11] AN_Serial Port AN_Serial Port

[12]

SIM868_GNSS_Application

Note

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II. Multiplexing Function

Table 47: Multiplexing function

Pin name Reset Pin number Mode 0(default) Mode 1 Mode 2 Mode 3

SIM1_DET I/PD 14 SIM1_DET GPIO EINT14

SIM2_DET I/PD 52 SIM2_DET GPIO EINT16

NETLIGHT I/PD 41 NETLIGHT GPIO UTXD

UART1_DTR I/PD 6 UART1_DTR GPIO EINT13

UART1_RI I/PD 7 UART1_RI GPIO EINT11

UART1_DCD I/PD 5 UART1_DCD GPIO URXD

UART1_CTS I/PD 4 UART1_CTS GPIO EINT12

UART1_RTS I/PD 3 UART1_RTS GPIO

MCCA3 I/PD 46 MCCA3 DAIPCMOUT(1.8V) GPIO EINT19

MCCA2 I/PD 47 MCCA2 DAICLK(1.8v) GPIO EINT18

MCCA1 I/PD 48 MCCA1 DAIPCMIN(1.8v) GPIO EINT17

MCCA0 I/PD 49 MCCA0 DAISYNC (1.8v) GPIO

MCCK I/PD 50 MCCK GPIO

MCCM0 I/PD 51 MCCM0 GPIO

Note: Multiplexing function need different software supply.

III. Terms and Abbreviations

Table 48: Terms and abbreviations

Abbreviation Description

ADC Analog-to-Digital Converter

AMR Adaptive Multi-Rate

CS Coding Scheme

CTS Clear to Send

DTE Data Terminal Equipment (typically computer, terminal, printer)

DTR Data Terminal Ready

DTX Discontinuous Transmission

EFR Enhanced Full Rate

EGSM Enhanced GSM

ESD Electrostatic Discharge

ETS European Telecommunication Standard

FR Full Rate

GPRS General Packet Radio Service

GSM Global Standard for Mobile Communications

HR Half Rate

MO Mobile Originated

MS Mobile Station (GSM engine), also referred to as TE

MT Mobile Terminated

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PAP Password Authentication Protocol

PBCCH Packet Broadcast Control Channel

PCB Printed Circuit Board

PCL Power Control Level

PCS Personal Communication System, also referred to as GSM 1900

PDU Protocol Data Unit

PPP Point-to-point protocol

RF Radio Frequency

RMS Root Mean Square (value)

RX Receive Direction

SIM Subscriber Identification Module

SMS Short Message Service

TE Terminal Equipment, also referred to as DTE

TX Transmit Direction

SINAD Signal to Noise and Distortion Ratio

UART Universal Asynchronous Receiver & Transmitter

URC Unsolicited Result Code

USSD Unstructured Supplementary Service Data

Phonebook abbreviations

FD SIM fix dialing phonebook

LD SIM last dialing phonebook (list of numbers most recently dialed)

MC Mobile Equipment list of unanswered MT calls (missed calls)

ON SIM (or ME) own numbers (MSISDNs) list

RC Mobile Equipment list of received calls

SM SIM phonebook

NC Not connect

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IV. Safety Caution

Table 49: Safety caution

Marks Requirements

When in a hospital or other health care facility, observe the restrictions about the use of mobiles.

Switch the cellular terminal or mobile off, medical equipment may be sensitive to not operate

normally for RF energy interference.

Switch off the cellular terminal or mobile before boarding an aircraft. Make sure it is switched off.

The operation of wireless appliances in an aircraft is forbidden to prevent interference with

communication systems. Forget to think much of these instructions may lead to the flight safety or

offend against local legal action, or both.

Do not operate the cellular terminal or mobile in the presence of flammable gases or fumes. Switch

off the cellular terminal when you are near petrol stations, fuel depots, chemical plants or where

blasting operations are in progress. Operation of any electrical equipment in potentially explosive

atmospheres can constitute a safety hazard.

Your cellular terminal or mobile receives and transmits radio frequency energy while switched on.

RF interference can occur if it is used close to TV sets, radios, computers or other electric

equipment.

Road safety comes first! Do not use a hand-held cellular terminal or mobile when driving a

vehicle, unless it is securely mounted in a holder for hands free operation. Before making a call

with a hand-held terminal or mobile, park the vehicle.

GSM cellular terminals or mobiles operate over radio frequency signals and cellular networks and

cannot be guaranteed to connect in all conditions, for example no mobile fee or a invalid SIM card.

While you are in this condition and need emergent help, please remember using emergency calls.

In order to make or receive calls, the cellular terminal or mobile must be switched on and in a

service area with adequate cellular signal strength.

Some networks do not allow for emergency call if certain network services or phone features are in

use (e.g. lock functions, fixed dialing etc.). You may have to deactivate those features before you

can make an emergency call.

Also, some networks require that a valid SIM card be properly inserted in the cellular terminal or

mobile.

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Contact us:
Shanghai SIMCom Wireless Solutions Co.,Ltd.

Address: Building A, SIM Technology Building, No. 633, Jinzhong Road, Shanghai, P. R. China
200335
Tel: [phone]
Fax: [phone]
URL: www.sim.com/wm

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