Quectel LTE Standard Module Series Supplement

EG21-G Mini PCIe
Hardware Design
LTE Standard Module Series
Rev. EG21-G_Mini_PCIe_Hardware_Design_V1.0
Date: 2019-11-21
Status: Released
www.quectel.com

LTE Standard Module Series
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About the Document
History
Revision
Date
Author
Description
1.0
2019-11-21
Lorry XU/
Ethan SHAN
Initial

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Contents
About the Document...................................................................................................................................2
Contents.......................................................................................................................................................3
Table Index...................................................................................................................................................5
Figure Index.................................................................................................................................................6
1Introduction ..........................................................................................................................................7
1.1. Safety Information......................................................................................................................8
2Product Concept..................................................................................................................................9
2.1. General Description...................................................................................................................9
2.2. Module Description....................................................................................................................9
2.3. Key Features ...........................................................................................................................10
2.4. Functional Diagram .................................................................................................................13
3Application Interfaces .......................................................................................................................14
3.1. Pin Assignment........................................................................................................................14
3.2. Pin Description.........................................................................................................................15
3.1. Operating Modes.....................................................................................................................18
3.2. Power Saving...........................................................................................................................19
3.2.1. Sleep Mode....................................................................................................................19
3.2.2. Airplane Mode................................................................................................................19
3.3. Power Supply...........................................................................................................................19
3.4. (U)SIM Interface ......................................................................................................................20
3.5. USB Interface ..........................................................................................................................22
3.6. UART Interface........................................................................................................................23
3.7. PCM and I2C Interfaces..........................................................................................................24
3.8. Control and Indication Signals.................................................................................................27
3.8.1. RI Signal.........................................................................................................................27
3.8.2. DTR Signal.....................................................................................................................27
3.8.3. W_DISABLE# Signal......................................................................................................28
3.8.4. PERST# Signal..............................................................................................................28
3.8.5. LED_WWAN# Signal .....................................................................................................29
3.8.6. WAKE# Signal................................................................................................................30
4GNSS Receiver...................................................................................................................................31
4.1. General Description.................................................................................................................31
4.2. GNSS Performance.................................................................................................................31
4.3. GNSS Frequency.....................................................................................................................32
5Antenna Connection..........................................................................................................................33
5.1. Antenna Connectors................................................................................................................33
5.1.1. Operating Frequency .....................................................................................................33
5.2. Antenna Requirements............................................................................................................35
5.3. Recommended Mating Plugs forAntenna Connection...........................................................36

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6Electrical, Reliability and Radio Characteristics............................................................................38
6.1. General Description.................................................................................................................38
6.2. Power Supply Requirements...................................................................................................38
6.3. I/O Requirements.....................................................................................................................39
6.4. RF Characteristics...................................................................................................................39
6.5. ESD Characteristics ................................................................................................................41
6.6. Current Consumption ..............................................................................................................42
6.7. Thermal Consideration............................................................................................................47
7Dimensions and Packaging..............................................................................................................49
7.1. General Description.................................................................................................................49
7.2. Mechanical Dimensions of EG21-G Mini PCIe .......................................................................49
7.3. Standard Dimensions of Mini PCI Express .............................................................................50
7.4. Packaging Specifications.........................................................................................................51
8Appendix A References.....................................................................................................................52

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Table Index
TABLE 1: DESCRIPTION OF EG21-G MINI PCIE.............................................................................................. 9
TABLE 2: KEY FEATURES OF EG21-G MINI PCIE......................................................................................... 10
TABLE 3: I/O PARAMETERS DEFINITION....................................................................................................... 15
TABLE 4: PIN DESCRIPTION........................................................................................................................... 15
TABLE 5: OVERVIEW OF OPERATING MODES............................................................................................. 18
TABLE 6: DEFINITION OF VCC_3V3 AND GND PINS.................................................................................... 19
TABLE 7: PIN DEFINITION OF (U)SIM INTERFACE ....................................................................................... 20
TABLE 8: PIN DEFINITION OF USB INTERFACE ........................................................................................... 22
TABLE 9: PIN DEFINITION OF MAIN UART INTERFACE............................................................................... 23
TABLE 10: PIN DEFINITION OF PCM AND I2C INTERFACES....................................................................... 24
TABLE 11: PIN DEFINITION OF CONTROLAND INDICATION SIGNALS...................................................... 27
TABLE 12: AIRPLANE MODE CONTROLLED BY HARDWARE METHOD..................................................... 28
TABLE 13: AIRPLANE MODE CONTROLLED BY SOFTWARE METHOD ..................................................... 28
TABLE 14: INDICATIONS OF NETWORK STATUS (AT+QCFG="LEDMODE",0, DEFAULT SETTING)......... 30
TABLE 15: INDICATIONS OF NETWORK STATUS (AT+QCFG="LEDMODE",2) ........................................... 30
TABLE 16: GNSS FREQUENCY....................................................................................................................... 32
TABLE 17: OPERATING FREQUENCIES ........................................................................................................ 33
TABLE 18: ANTENNA REQUIREMENTS.......................................................................................................... 35
TABLE 19: POWER SUPPLY REQUIREMENTS.............................................................................................. 38
TABLE 20: I/O REQUIREMENTS...................................................................................................................... 39
TABLE 21: EG21-G MINI PCIE CONDUCTED RF OUTPUT POWER............................................................. 39
TABLE 22: EG21-G MINI PCIE CONDUCTED RF RECEIVING SENSITIVITY............................................... 40
TABLE 23: ESD CHARACTERISTICS OF EG21-G MINI PCIE........................................................................ 41
TABLE 24: CURRENT CONSUMPTION OF EG21-G MINI PCIE .................................................................... 42
TABLE 25: GNSS CURRENT CONSUMPTION OF EG21-G MINI PCIE......................................................... 46
TABLE 26: RELATED DOCUMENTS................................................................................................................ 52
TABLE 27: TERMS AND ABBREVIATIONS...................................................................................................... 52

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Figure Index
FIGURE 1: FUNCTIONAL DIAGRAM ............................................................................................................... 13
FIGURE 2: PIN ASSIGNMENT ......................................................................................................................... 14
FIGURE 3: REFERENCE CIRCUIT OF POWER SUPPLY .............................................................................. 20
FIGURE 4: REFERENCE CIRCUIT OF (U)SIM INTERFACE WITH AN 8-PIN (U)SIM CARD CONNECTOR 21
FIGURE 5: REFERENCE CIRCUIT OF (U)SIM INTERFACE WITH A6-PIN (U)SIM CARD CONNECTOR... 21
FIGURE 6: REFERENCE CIRCUIT OF USB INTERFACE .............................................................................. 22
FIGURE 7: REFERENCE CIRCUIT OF POWER SUPPLY .............................................................................. 24
FIGURE 8: TIMING IN PRIMARY MODE.......................................................................................................... 25
FIGURE 9: TIMING IN AUXILIARY MODE........................................................................................................ 26
FIGURE 10: REFERENCE CIRCUIT OF PCM AND I2C APPLICATION WITH AUDIO CODEC..................... 26
FIGURE 11: RI BEHAVIORS............................................................................................................................. 27
FIGURE 12: TIMING OF RESETTING MODULE ............................................................................................. 29
FIGURE 13: LED_WWAN# SIGNAL REFERENCE CIRCUIT DIAGRAM ........................................................ 29
FIGURE 14: WAKE# BEHAVIORS.................................................................................................................... 30
FIGURE 15: DIMENSIONS OF THE RECEPTACLE RF CONNECTORS (UNIT: MM).................................... 36
FIGURE 16: MECHANICALS OF U.FL-LP MATING PLUGS ........................................................................... 36
FIGURE 17: SPACE FACTOR OF MATING PLUGS (UNIT: MM)..................................................................... 37
FIGURE 18: REFERENCED HEATSINK DESIGN ........................................................................................... 47
FIGURE 19: MECHANICAL DIMENSIONS OF EG21-G MINI PCIE................................................................ 49
FIGURE 20: STANDARD DIMENSIONS OF MINI PCI EXPRESS................................................................... 50
FIGURE 21: DIMENSIONS OF THE MINI PCI EXPRESS CONNECTOR (MOLEX 679105700).................... 51

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1Introduction
This document defines EG21-G Mini PCIe module, and describes its air interfaces and hardware
interfaces which are connected with customers’ applications.
This document helps customers quickly understand module interface specifications, electrical
characteristics, mechanical specifications and other related information of the module. To facilitate
application designs, it also includes some reference designs for customers’ reference. The document,
coupled with application notes and user guides, makes it easy to design and set up wireless applications
with EG21-G Mini PCIe.

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1.1. Safety Information
The following safety precautions must be observed during all phases of operation, such as usage, service
or repair of any cellular terminal or mobile incorporating EG21-G Mini PCIe module. Manufacturers of the
cellular terminal should send the following safety information to users and operating personnel, and
incorporate these guidelines into all manuals supplied with the product. If not so, Quectel assumes no
liability for customers’ failure to comply with these precautions.
Full attention must be given to driving at all times in order to reduce the risk of an
accident. Using a mobile while driving (even with a handsfree kit) causes
distraction and can lead to an accident. Please comply with laws and regulations
restricting the use of wireless devices while driving.
Switch off the cellular terminal or mobile before boarding an aircraft. The operation
of wireless appliances in an aircraft is forbidden to prevent interference with
communication systems. If the device offers an Airplane Mode, then it should be
enabled prior to boarding an aircraft. Please consult the airline staff for more
restrictions on the use of wireless devices on boarding the aircraft.
Wireless devices may cause interference on sensitive medical equipment, so
please be aware of the restrictions on the use of wireless devices when in
hospitals, clinics or other healthcare facilities.
Cellular terminals or mobiles operating over radio signals and cellular network
cannot be guaranteed to connect in all possible conditions (for example, with
unpaid bills or with an invalid (U)SIM card). When emergent help is needed in such
conditions, please remember using emergency call. In order to make or receive a
call, the cellular terminal or mobile must be switched on in a service area with
adequate cellular signal strength.
The cellular terminal or mobile contains a transmitter and receiver.When it is ON, it
receives and transmits radio frequency signals. RF interference can occur if it is
used close to TV set, radio, computer or other electric equipment.
In locations with potentially explosive atmospheres, obey all posted signs to turn
off wireless devices such as your phone or other cellular terminals. Areas with
potentially explosive atmospheres include fuelling areas, below decks on boats,
fuel or chemical transfer or storage facilities, areas where the air contains
chemicals or particles such as grain, dust or metal powders, etc.

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2Product Concept
2.1. General Description
EG21-G Mini PCIe module provides data connectivity on LTE-FDD, LTE-TDD, DC-HSDPA, HSPA+,
HSDPA, HSUPA, WCDMA, EDGE and GPRS networks with PCI Express Mini Card 1.2 standard interface.
It supports embedded operating systems such as Linux, Android, etc., and also provides audio,
high-speed data transmission and GNSS functionalities for customers’ applications.
EG21-G Mini PCIe module can be applied in the following fields:
PDA and Laptop Computer
Remote Monitor System
Vehicle System
Wireless POS System
Intelligent Meter Reading System
Wireless Router and Switch
Other Wireless Terminal Devices
2.2. Module Description
The following table shows the supported frequency bands, GNSS and digital audio functions of EG21-G
Mini PCIe module.
Table 1: Description of EG21-G Mini PCIe
Frequency Bands/
GNSS/
Digital Audio
EG21-G Mini PCIe
LTE-FDD
B1/B2/B3/B4/B5/B7/B8/B12/B13/B18/B19/B20/B25/B26/B28
LTE-TDD
B38/B39/B40/B41
WCDMA
B1/B2/B4/B5/B6/B8/B19

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2.3. Key Features
The following table describes the detailed features of EG21-G Mini PCIe module.
Table 2: Key Features of EG21-G Mini PCIe
GSM
850/900/1800/1900MHz
GNSS (Optional)
GPS, GLONASS, BeiDou (Compass), Galileo, QZSS
Digital Audio (PCM)
Supported
Features
Description
Function Interface
PCI Express Mini Card 1.2 Standard Interface
Power Supply
Supply voltage: 3.0V~3.6V
Typical supply voltage: 3.3V
Transmitting Power
Class 4 (33dBm±2dB) for GSM850
Class 4 (33dBm±2dB) for EGSM900
Class 1 (30dBm±2dB) for DCS1800
Class 1 (30dBm±2dB) for PCS1900
Class E2 (27dBm±3dB) for GSM850 8-PSK
Class E2 (27dBm±3dB) for EGSM900 8-PSK
Class E2 (26dBm±3dB) for DCS1800 8-PSK
Class E2 (26dBm±3dB) for PCS1900 8-PSK
Class 3 (24dBm+1/-3dB) for WCDMAbands
Class 3 (23dBm±2dB) for LTE-FDD bands
Class 3 (23dBm±2dB) for LTE-TDD bands
LTE Features
Support up to non-CA Cat 1 FDD and TDD
Support 1.4/3/5/10/15/20MHz RF bandwidth
Support MIMO in DL direction
LTE-FDD: Max 10Mbps (DL), Max 5Mbps (UL)
LTE-TDD: Max 8.96Mbps (DL), Max 3.1Mbps (UL)
UMTS Features
Support 3GPP R8 DC-HSDPA, HSPA+, HSDPA, HSUPA and WCDMA
Support QPSK,16-QAM and 64-QAM modulation
DC-HSDPA: Max 42Mbps (DL)
HSUPA: Max 5.76Mbps (UL)
WCDMA: Max 384Kbps (DL), Max 384Kbps (UL)
GSM Features
GPRS:
Support GPRS multi-slot class 33 (33 by default)
Coding scheme: CS-1, CS-2, CS-3 and CS-4

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Max 107Kbps (DL), Max 85.6Kbps (UL)
EDGE:
Support EDGE multi-slot class 33 (33 by default)
Support GMSK and 8-PSK for different MCS (Modulation and Coding
Scheme)
Downlink coding schemes: CS 1-4 and MCS 1-9
Uplink coding schemes: CS 1-4 and MCS 1-9
Max 296Kbps (DL), Max 236.8Kbps (UL)
Internet Protocol Features
Support TCP/UDP/PPP/FTP/FTPS/HTTP/HTTPS/NTP/PING/QMI/NITZ/
SMTP/SSL/MQTT/CMUX/SMTPS/MMS*/FILE* protocols
Support PAP (Password Authentication Protocol) and CHAP (Challenge
Handshake Authentication Protocol) protocols which are usually used for
PPP connection
SMS
Text and PDU modes
Point-to-point MO and MT
SMS cell broadcast
SMS storage: ME by default
(U)SIM Interface
Support USIM/SIM card: 1.8V, 3.0V
UART Interface
Main UART:
Support RTS and CTS hardware flow control
Baud rate can reach up to 230400bps, 115200bps by default
Used for AT command communication
Audio Features
Support one digital audio interface: PCM interface
GSM: HR/FR/EFR/AMR/AMR-WB
WCDMA:AMR/AMR-WB
LTE: AMR/AMR-WB
Support echo cancellation and noise suppression
PCM Interface
Support 16-bit linear data format
Support long frame synchronization and short frame synchronization
Support master and slave modes, but must be the master in long frame
synchronization
USB Interface
Compliant with USB 2.0 specification (slave only); the data transfer rate
can reach up to 480Mbps
Used for AT command communication, data transmission, firmware
upgrade, software debugging, GNSS NMEA output and voice over USB.
Support USB serial drivers for: Windows 7/8/8.1/10, Linux 2.6~5.4, Android
4.x/5.x/6.x/7.x/8.x/9.x, etc.
Antenna Connectors
Include main antenna, diversity antenna and GNSS antenna receptacle
connectors
Rx-diversity (Optional)
Support LTE/WCDMA Rx-diversity
GNSS Features
Gen8C Lite of Qualcomm
Protocol: NMEA 0183

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1. 1) Within operation temperature range, the module is 3GPP compliant.
2. 2) Within extended temperature range, the module remains the ability to establish and maintain a
voice, SMS, data transmission, emergency call*, etc. There is no unrecoverable malfunction. There
are also no effects on radio spectrum and no harm to radio network. Only one or more parameters
like Pout might reduce in their value and exceed the specified tolerances. When the temperature
returns to normal operation temperature levels, the module will meet 3GPP specifications again.
3. “*” means under development.
Data update rate: 1Hz by default
AT Commands
Compliant with 3GPP TS 27.007, 27.005 and Quectel enhanced AT
commands
Physical Characteristics
Size: (51.0±0.15)mm ×(30.0±0.15)mm ×(4.9±0.2)mm
Weight: approx. 9.8g
Temperature Range
Operation temperature range: -35°C ~ +75°C 1)
Extended temperature range: -40°C ~ +80°C 2)
Storage temperature range: -40°C ~ +90°C
Firmware Upgrade
Upgrade via USB interface or DFOTA
RoHS
All hardware components are fully compliant with EU RoHS directive
NOTES

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2.4. Functional Diagram
The following figure shows the block diagram of EG21-G Mini PCIe.
EG21-G Module
PCM&I2C
Mini PCI Express
Interface
USB
W_DISABLE#
PERST#
LED_WWAN#
Main
Antenna
Connector
VCC
Main
Antenna
VBAT
GNSS
Antenna
Connector
GNSS
Antenna
Boost
Circuit
Diversity
Antenna
Connector
Diversity
Antenna
WAKE#
UART
DTR
RI
(U)SIM
Figure 1: Functional Diagram

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3Application Interfaces
The physical connections and signal levels of EG21-G Mini PCIe comply with PCI Express Mini Card
Electromechanical Specification. This chapter mainly describes the definition and application of the
following interfaces/pins of EG21-G Mini PCIe:
Power supply
(U)SIM interface
USB interface
UART interface
PCM and I2C interfaces
Control and indication signals
3.1. Pin Assignment
The following figure shows the pin assignment of EG21-G Mini PCIe module. The top side contains
EG21-G module and antenna connectors.
PIN2
PIN52
BOT
PIN1
PIN51
TOP
Pin Name Pin No.
WAKE# 1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33
35
37
39
41
43
45
47
49
51
RESERVED
RESERVED
RESERVED
GND
UART_RX
UART_TX
GND
RI
RESERVED
GND
UART_CTS
UART_RTS
GND
GND
DTR
RESERVED
GND
GND
VCC_3V3
VCC_3V3
GND
PCM_CLK
PCM_DOUT
PCM_DIN
PCM_SYNC
Pin Name
Pin No.
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
42
44
46
48
50
52
VCC_3V3
GND
NC
USIM_VDD
USIM_DATA
USIM_CLK
USIM_RST
RESERVED
GND
W_DISABLE#
PERST#
RESERVED
GND
NC
I2C_SCL
I2C_SDA
GND
USB_DM
USB_DP
GND
LED_WWAN#
USIM_PRESENCE
RESERVED
NC
GND
VCC_3V3
Figure 2: Pin Assignment

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3.2. Pin Description
The following tables show the pin definition and description of the 52 pins on EG21-G Mini PCIe.
Table 3: I/O Parameters Definition
Table 4: Pin Description
Type
Description
DI
Digital Input
DO
Digital Output
IO
Bidirectional
OC
Open Collector
PI
Power Input
PO
Power Output
Pin No.
Mini PCI Express
Standard Name
EG21-G Mini PCIe
Pin Name
I/O
Description
Comment
1
WAKE#
WAKE#
OC
Output signal used to
wake up the host.
2
3.3Vaux
VCC_3V3
PI
3.0V~3.6V, typically
3.3V DC supply
3
COEX1
RESERVED
DI
Reserved
It is prohibited to
be pulled up
high before
startup.
4
GND
GND
Mini card ground
5
COEX2
RESERVED
DO
Reserved
It is prohibited to
be pulled up
high before
startup.
6
1.5V
NC
Not connected
7
CLKREQ#
RESERVED
Reserved
8
UIM_PWR
USIM_VDD
PO
Power supply for the

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(U)SIM card
9
GND
GND
Mini card ground
10
UIM_DATA
USIM_DATA
IO
Data signal of (U)SIM
card
11
REFCLK-
UART_RX
DI
UART receive data
Connect to
DTE’s TX.
12
UIM_CLK
USIM_CLK
DO
Clock signal of
(U)SIM card
13
REFCLK+
UART_TX
DO
UART transmit data
Connect to
DTE’s RX.
14
UIM_RESET
USIM_RST
DO
Reset signal of
(U)SIM card
15
GND
GND
Mini card ground
16
UIM_VPP
RESERVED
Reserved
17
RESERVED
RI
DO
Ring indication
18
GND
GND
Mini card ground
19
RESERVED
RESERVED
Reserved
20
W_DISABLE#
W_DISABLE#
DI
Airplane mode control
Pulled up by
default.
Active low.
21
GND
GND
Mini card ground
22
PERST#
PERST#
DI
Fundamental reset
signal
Pulled up by
default.
Active low
23
PERn0
UART_CTS
DI
UART clear to send
Connect to
DTE’s RTS.
24
3.3Vaux
RESERVED
Reserved
25
PERp0
UART_RTS
DO
UART request to send
Connect to
DTE’s CTS.
26
GND
GND
Mini card ground
27
GND
GND
Mini card ground
28
1.5V
NC
Not connected
29
GND
GND
Mini card ground

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30
SMB_CLK
I2C_SCL
DO
I2C serial clock
Require
external pull-up
to 1.8V.
31
PETn0
DTR
DI
Sleep mode control
32
SMB_DATA
I2C_SDA
IO
I2C serial data
Require
external pull-up
to 1.8V.
33
PETp0
RESERVED
Reserved
34
GND
GND
Mini card ground
35
GND
GND
Mini card ground
36
USB_D-
USB_DM
IO
USB differential data
(-)
Require
differential
impedance of
90Ω.
37
GND
GND
Mini card ground
38
USB_D+
USB_DP
IO
USB differential data
(+)
Require
differential
impedance of
90Ω.
39
3.3Vaux
VCC_3V3
PI
3.0V~3.6V, typically
3.3V DC supply
40
GND
GND
Mini card ground
41
3.3Vaux
VCC_3V3
PI
3.0V~3.6V, typically
3.3V DC supply
42
LED_WWAN#
LED_WWAN#
OC
LED signal for
indicating the network
status of the module
Active low
43
GND
GND
Mini card ground
44
LED_WLAN#
USIM_PRESENCE
DI
(U)SIM card insertion
detection
45
RESERVED
PCM_CLK
IO
PCM clock signal
46
LED_WPAN#
RESERVED
Reserved
47
RESERVED
PCM_DOUT
DO
PCM data output
48
1.5V
NC
Not connected
49
RESERVED
PCM_DIN
DI
PCM data input

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
Keep all NC, reserved and unused pins unconnected.
3.1. Operating Modes
The following table briefly outlines the operating modes to be mentioned in the following chapters.
Table 5: Overview of Operating Modes
Mode
Details
Normal
Operation
Idle
Software is active. The module has registered on the network, and it is
ready to send and receive data.
Talk/Data
Network connection is ongoing. In this mode, the power consumption is
decided by network setting and data transfer rate.
Minimum
Functionality
Mode
AT+CFUN command can set the module to a minimum functionality mode without
removing the power supply. In this case, both RF function and (U)SIM card will be
invalid.
Airplane Mode
AT+CFUN command or W_DISABLE# pin can set the module to airplane mode. In
this case, RF function will be invalid.
Sleep Mode
In this mode, the current consumption of the module will be reduced to the minimal
level. In this mode, the module can still receive paging message, SMS, voice call and
TCP/UDP data from the network normally.
50
GND
GND
Mini card ground
51
RESERVED
PCM_SYNC
IO
PCM frame
synchronization
52
3.3Vaux
VCC_3V3
PI
3.0V~3.6V, typically
3.3V DC supply
NOTE

LTE Standard Module Series
EG21-G Mini PCIe Hardware Design
EG21-G_Mini_PCIe_Hardware_Design 19 / 54
3.2. Power Saving
3.2.1. Sleep Mode
EG21-G Mini PCIe is able to reduce its current consumption to a minimum value in sleep mode. There are
three preconditions must be met to make the module enter sleep mode.
Execute AT+QSCLK=1 to enable sleep mode.
Ensure the DTR is kept at high level or be kept open.
The host’s USB bus, which is connected with the module’s USB interface, enters suspend state.
3.2.2. Airplane Mode
When the module enters airplane mode, the RF function will be disabled, and allAT commands related to
it will be inaccessible. For more details, please refer to Chapter 3.10.3.
3.3. Power Supply
The following table shows pin definition of VCC_3V3 pins and ground pins.
Table 6: Definition of VCC_3V3 and GND Pins
The typical supply voltage of EG21-G Mini PCIe is 3.3V. In the 2G network, the input peak current may
reach 2.7A during the transmitting time. Therefore, the power supply must be able to provide a rated
output current of 2.7A at least, and a bypass capacitor of no less than 470µF with low ESR should be
used to prevent the voltage from dropping. If the switching power supply is used to supply power to the
module, the power device and power supply routing traces of the switching power supply should avoid the
antennas as much as possible to prevent EMI interference.
The following figure shows a reference design of power supply where R2 and R3 are 1% tolerance
resistors and C3 is a low-ESR capacitor.
Pin Name
Pin No.
I/O
Power Domain
Description
VCC_3V3
2, 39, 41, 52
PI
3.0V~3.6V
Typically 3.3V DC supply
GND
4, 9, 15, 18, 21,
26, 27, 29, 34, 35,
37, 40, 43, 50
Mini card ground