Quectel FC21 Supplement

FC21 Hardware Design
Wi-Fi&BT Module Series
Version: 1.0
Date: 2020-08-13
Status: Preliminary
www.quectel.com

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About the Document
Revision History
Version Date Author Description
1.0 2020-08-13 Power JIN/Kris ZHANG Initial

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Contents
About the Document .............................................................................................................................. 2
Contents ................................................................................................................................................. 3
Table Index ............................................................................................................................................. 5
Figure Index ............................................................................................................................................ 6
1 Introduction ..................................................................................................................................... 7
1.1. Safety Information ................................................................................................................... 8
2 Product Concept ............................................................................................................................. 9
2.1 General Description ................................................................................................................ 9
2.2 Key Features .......................................................................................................................... 9
2.3 Functional Diagram ............................................................................................................... 11
2.4 Evaluation Board .................................................................................................................. 12
3 Application Interfaces ................................................................................................................... 13
3.1. General Description .............................................................................................................. 13
3.2. Pin Assignment ..................................................................................................................... 14
3.3. Pin Description ..................................................................................................................... 15
3.4. Power Supply ....................................................................................................................... 19
3.4.1. Pin Introduction .......................................................................................................... 19
3.5. Wireless Connectivity Interfaces ........................................................................................... 20
3.5.1. Wi-Fi Interface ............................................................................................................ 20
3.5.1.1. WAKE_ON_WIRELESS .................................................................................... 21
3.5.1.2. WAKE_EN ........................................................................................................ 21
3.5.1.3. SDIO Interface .................................................................................................. 22
3.5.2. BT Interface* .............................................................................................................. 23
3.5.2.1. BT_EN .............................................................................................................. 23
3.5.2.2. BT_WAKE_HOST ............................................................................................. 24
3.5.2.3. PCM Interface ................................................................................................... 24
3.5.2.4. BT_UART Interface ........................................................................................... 25
3.5.3. Coexistence Interface ................................................................................................. 26
3.6. Other Interfaces .................................................................................................................... 27
3.6.1. DBG_TXD Interface ................................................................................................... 27
3.6.2. 32KHz_IN Interface .................................................................................................... 27
3.7. Antenna Interface ................................................................................................................. 28
3.7.1. Pin Definition of RF Antenna Interface ........................................................................ 28
3.7.2. Operating Frequency .................................................................................................. 28
3.7.3. Reference Designs ..................................................................................................... 28
3.7.4. Reference Design of RF Layout ................................................................................. 29
3.7.5. Antenna Requirements ............................................................................................... 31
3.7.6. Recommended RF Connector for Antenna Installation ............................................... 32

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4 Electrical, Reliability and Radio Characteristics ......................................................................... 34
4.1. General Description .............................................................................................................. 34
4.2. Electrical Characteristics ....................................................................................................... 34
4.3. I/O Interface Characteristics .................................................................................................. 35
4.4. Current Consumption ............................................................................................................ 35
4.4.1. Wi-Fi Current Consumption ........................................................................................ 35
4.4.2. BLE Current Consumption .......................................................................................... 37
4.5. RF Performance ................................................................................................................... 37
4.5.1. Wi-Fi Performance ..................................................................................................... 37
4.5.2. BLE Performance ....................................................................................................... 39
4.6. Electrostatic Discharge ......................................................................................................... 40
5 Mechanical Dimensions ................................................................................................................ 41
5.1. Mechanical Dimensions of the Module .................................................................................. 41
5.2. Recommended Footprint and Stencil Design......................................................................... 43
5.3. Top and Bottom Views of the Module .................................................................................... 45
6 Storage, Manufacturing and Packaging ....................................................................................... 46
6.1. Storage ................................................................................................................................. 46
6.2. Manufacturing and Soldering ................................................................................................ 47
6.3. Packaging ............................................................................................................................. 49
7 Appendix A References ................................................................................................................ 50

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Table Index
Table 1: FC21 Module ............................................................................................................................. 7
Table 2: Key Features ............................................................................................................................. 9
Table 3: I/O Parameters Definition ......................................................................................................... 15
Table 4: Pin Description of FC21 Module ............................................................................................... 15
Table 5: Power Supply Pins and GND Pins ............................................................................................ 19
Table 6: Pin Definition of WAKE_ON_WIRELESS ................................................................................. 21
Table 7: Pin Definition of WLAN_EN ...................................................................................................... 21
Table 8: Pin Definition of SDIO Interface ................................................................................................ 22
Table 9: Pin Definition of BT_EN............................................................................................................ 23
Table 10: Pin Definition of BT_WAKE_HOST ......................................................................................... 24
Table 11: Pin Definition of PCM Interface ............................................................................................... 24
Table 12: Pin Definition of UART Interface ............................................................................................. 25
Table 13: Pin Definition of Coexistence Interface ................................................................................... 26
Table 14: Pin Definition of DBG_TXD Interface ...................................................................................... 27
Table 15: Pin Definition of 32KHz_IN Interface ...................................................................................... 27
Table 16: Pin Definition of RF Antenna Interface .................................................................................... 28
Table 17: Operating Frequency ............................................................................................................. 28
Table 18: Antenna Cable Requirements ................................................................................................. 31
Table 19: Antenna Requirements ........................................................................................................... 32
Table 20: Absolute Maximum Ratings .................................................................................................... 34
Table 21: Recommended Operating Conditions ..................................................................................... 35
Table 22: General DC Electrical Characteristics ..................................................................................... 35
Table 23: Wi-Fi Current Consumption .................................................................................................... 35
Table 24: BLE Current Consumption During Non-signaling .................................................................... 37
Table 25: Conducted RF Output Power at 2.4GHz ................................................................................. 37
Table 26: Conducted RF Output Power at 5GHz .................................................................................... 38
Table 27: Conducted RF Receiving Sensitivity at 2.4GHz ...................................................................... 38
Table 28: Conducted RF Receiving Sensitivity at 5GHz ......................................................................... 39
Table 29: BLE Transmitting and Receiving Performance........................................................................ 39
Table 30: Electrostatic Discharge Characteristics (25ºC, 45% Relative Humidity) .................................. 40
Table 31: Recommended Thermal Profile Parameters ........................................................................... 48
Table 32: Related Documents ................................................................................................................ 50
Table 33: Terms and Abbreviations ........................................................................................................ 50

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Figure Index
Figure 1: Functional Diagram of FC21 Module....................................................................................... 11
Figure 2: Pin Assignment of FC21 Module ............................................................................................. 14
Figure 3: Reference Circuit for VDD_3V3 .............................................................................................. 19
Figure 4: Timing of Turning on/off FC21 Module .................................................................................... 20
Figure 5: Wi-Fi Interface Connection ..................................................................................................... 20
Figure 6: SDIO Interface Connection ..................................................................................................... 22
Figure 7: Block Diagram of BT Interface Connection ............................................................................. 23
Figure 8: Reference Design for PCM Interface ...................................................................................... 25
Figure 9: Reference Design for UART Interface Connection .................................................................. 25
Figure 10: Coexistence Interface Connection ........................................................................................ 26
Figure 11: Reference Circuit for RF Antenna Interface ........................................................................... 29
Figure 12: Reference Circuit for RF Antenna Interface (Vehicle Applications) ........................................ 29
Figure 13: Microstrip Design on a 2-layer PCB ...................................................................................... 30
Figure 14: Coplanar Waveguide Design on a 2-layer PCB ..................................................................... 30
Figure 15: Coplanar Waveguide Design on a 4-layer PCB (Layer 3 as Reference Ground) ................... 30
Figure 16: Coplanar Waveguide Design on a 4-layer PCB (Layer 4 as Reference Ground) ................... 31
Figure 17: Dimensions of the U.FL-R-SMT Connector (Unit: mm) .......................................................... 32
Figure 18: Mechanicals of U.FL-LP Connectors ..................................................................................... 33
Figure 19: Space Factor of Mated Connector (Unit: mm) ....................................................................... 33
Figure 20: Top and Side Dimensions ..................................................................................................... 41
Figure 21: Bottom Dimensions .............................................................................................................. 42
Figure 22: Recommended Footprint ...................................................................................................... 43
Figure 23: Recommended Stencil Design .............................................................................................. 44
Figure 24: Top View of the Module ......................................................................................................... 45
Figure 25: Bottom View of the Module ................................................................................................... 45
Figure 26: Recommended Reflow Soldering Thermal Profile ................................................................. 47
Figure 27: Tape Dimensions .................................................................................................................. 49
Figure 28: Reel Dimensions .................................................................................................................. 49

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1
Introduction
This document defines the FC21 module and describes its air interface and hardware interfaces which
are connected to the customers’ applications.
The document can help customers quickly understand module interface specifications, electrical and
mechanical details, as well as other related information of the module. In combination with Quectel
EC2x&EG2X-G1) modules, FC21 module can help customers to design and set up LTE+Wi-Fi/BT
applications easily.
Table 1: FC21 Module
1) In this document, EC2x refers to Quectel EC25, EC21 and EC20 R2.1 modules and EG2x-G refers to
Quectel EG21-G and EG25-G modules.
Module Wi-Fi BT
FC21 2.4GHz and 5GHz BT 4.2
NOTE

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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 FC21 module. Manufacturers of the cellular
terminal should notify users and operating personnel of the following safety information by incorporating
these guidelines into all manuals of the product. Otherwise, Quectel assumes no liability for customers’
failure to comply with these precautions.
Full attention must be paid 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 there is an Airplane Mode, it should be enabled prior to
boarding an aircraft. Please consult the airline staff for more restrictions on the use
of wireless devices on an 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 signal and cellular network
cannot be guaranteed to connect in certain conditions, such as when the mobile bill
is unpaid or the (U)SIM card is invalid. When emergent help is needed in such
conditions, use emergency call if the device supports it. 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. In an emergency, the device with emergency call
function cannot be used as the only contact method considering network
connection cannot be guaranteed under all circumstances.
The cellular terminal or mobile contains a transceiver. When it is ON, it receives
and transmits radio frequency signals. RF interference can occur if it is used close
to TV sets, radios, computers or other electric equipment.
In locations with explosive or potentially explosive atmospheres, obey all posted
signs and turn off wireless devices such as mobile phone or other cellular
terminals. Areas with explosive or potentially explosive atmospheres include
fuelling areas, below decks on boats, fuel or chemical transfer or storage facilities,
and areas where the air contains chemicals or particles such as grain, dust or
metal powders.

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2
Product Concept
2.1 General Description
FC21 is a low-power cost-effective Wi-Fi/BT module based on QCA1023. FC21 supports 1×1 IEEE
802.11a/b/g/n/ac WLAN standards and BT 4.2 (BLE and SPP) and provides a low-power SDIO 3.0
interface for Wi-Fi and UART&PCM interfaces for BT*, and also supports LTE/WLAN coexistence.
FC21 module is a SMT module, with 38 LCC pins and 14 LGA pins. The module package is compact and
the size is only 16.6mm × 13mm × 2.1mm.
1. “*” means under development.
2. BLE function of FC21 module is available.
2.2 Key Features
The following table describes the detailed features of FC21 module.
Table 2: Key Features
Features Description
Power Supply
VDD_3V3 Power Supply:
Voltage Range: 3.14V~3.46V
Typical voltage: 3.3V
I/O supply voltage:
Voltage Range: 1.71V~3.46V
Typical voltage: 1.8V
Wi-Fi Data Rates
 802.11b: 1Mbps, 2Mbps, 5.5Mbps, 11Mbps
 802.11g: 6Mbps, 9Mbps, 12Mbps, 18Mbps, 24Mbps, 36Mbps, 48Mbps,
54Mbps
NOTES
批注 [RL1]: 这里面不要加上
FC21 模块为贴片式模块，共
有38 个LCC 引脚和 14 个LGA
引脚；模块封装紧凑，尺寸仅
为16.6 mm × 13 mm × 2.1
mm。
批注 [RL2]: 中文这里没加星
号，中文是否要加上
批注 [RL3]: 中文这里没有这一
条，中文是否要加上

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1. 1) Within extended temperature range, the module remains the ability for data transmission. 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 the normal operating temperature levels, the module
will meet IEEE compliant again.
2. “*” means under development.
 802.11n (20MHz): 7.2Mbps, 14.2Mbps, 21.7Mbps, 28.9Mbps,
43.3Mbps, 57.8Mbps, 65Mbps, 72.2Mbps
 802.11n (40MHz): 15Mbps, 30Mbps, 45Mbps, 60Mbps, 90Mbps,
120Mbps, 150Mbps
 802.11a: 6Mbps, 9Mbps, 12Mbps, 18Mbps, 24Mbps, 36Mbps, 48Mbps,
54Mbps
 802.11ac: VHT20 (MCS0~MCS8), VHT40 (MCS0~MCS9), VHT80
(MCS0~MCS9)
Wi-Fi Transmitting
Power  TBD
Wi-Fi Protocol Features  IEEE 802.11a/b/g/n/ac
Wi-Fi Modulation  BPSK, QPSK, CCK, 16QAM, 64QAM, 256QAM
Wi-Fi Operation Modes  AP
 STA
BT Protocol Features
 GATT*
 SPP*
BT Operation Modes  BT* BLE
BT Modulation  GFSK, 8-DPSK,π/4-DQPSK
Wireless Connectivity
Interfaces
 Wi-Fi：SDIO 3.0
 BT：UART and PCM
Antenna Interface Wi-Fi/BT antenna interface, 50Ω impedance
Physical Characteristics
Dimensions: (16.6 ±0.15) mm × (13.0 ±0.15) mm × (2.1±0.2) mm
Package: LCC
Weight: TBD
Temperature Ranges Extended temperature range: -40 to +85°C1)
Storage temperature range: -45 to +95°C
RoHS All hardware components are fully compliant with EU RoHS directive
NOTES
批注 [RL4]: 中文里没有这个，
中文是否要加上

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2.3 Functional Diagram
The following figure shows a block diagram of FC21 module and illustrates the major functional parts:
 Power supply
 Wireless Connectivity Interfaces
- Wi-Fi interface
- BT interface
- Coexistence interface
 Antenna interface
 Other interfaces
- DBG_TXD
- 32KHz_IN interface
Figure 1: Functional Diagram of FC21 Module
FC21_SA version has 2.4G Filter, FC21_SD version does not have 2.4G Filter.
NOTE
批注 [RL5]:
FC21_SA 版本带 2.4G Filter，
FC21_SD版本不带 2.4G Filter.
要不要加这个备注
批注 [RL6R5]:

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2.4 Evaluation Board
In order to help customers to develop applications with FC21 module, Quectel supplies an evaluation
board (UMTS&LTE EVB), an RS-232 to USB converter cable, a USB data cable, a power adapter, 4
antennas and other peripherals to control or test the module. For details, please refer to document [1].

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3
Application Interfaces
3.1. General Description
FC21 module is equipped with 38 LCC pads and 14 LGA pads that can be connected to cellular
application platform. The subsequent chapters will provide detailed descriptions of the following
interfaces:
 Power supply
 Wireless Connectivity Interfaces
- Wi-Fi interface
- BT interface
- Coexistence interface
 Other interfaces
- DBG_TXD interface
- 32KHz_IN interface
 Antenna interface

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3.2. Pin Assignment
32 34 35
33
36
37 38
29
28
30
31
27
26
24
23
25
22
21
20
19 17 16
18
15
14 13
47
48
49
46
1)
WLAN_EN
GND
RF_ANT
GND
GND
SDIO_CMD
SDIO_CLK
SDIO_D0
SDIO_D1
SDIO_D2
SDIO_D3
VDD_3V3
GND
GND
RESERVED
DBG_TXD
BT_UART_CTS
1)
BT_EN
1)
VIO
RESERVED
GND
LTE_UART_TXD
LTE_UART_RXD
BT_UART_RTS
1)
3
4
2
1
5
6
8
9
7
10
11
12
51 50 52
40
39
41
42
44 4543
PCM_IN
1)
PCM_SYNC
1)
PCM_CLK
1)
PCM_OUT
1)
BT_UART_TXD
1)
BT_UART_RXD
1)
32KHz_IN 2
)
GND GND
RESERVED
RESERVED RESERVED RESERVED
WAKE_ON_WIRELESS
Power
GND
WLAN Reserved Other signals RF
BT
Figure 2: Pin Assignment of FC21 Module
1. Please keep all RESERVED pins open.
2. 1) indicates that pins 7, 8, 10, 13~18 and 46 are BT function pins. BT function is under development.
3. 2) indicates that 32KHz_IN is reserved on FC21 module since the sleep function is under
development.
NOTES

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3.3. Pin Description
The following tables show the pin definition of FC21 module.
Table 3: I/O Parameters Definition
Table 4: Pin Description of FC21 Module
Type Description
DI Digital input
DO Digital output
IO Bidirectional
PI Power input
Power Supply
Pin Name Pin No. I/O Description DC Characteristics Comment
VDD_3V3 21 PI Main power supply
for module
Vmax=3.46V
Vmin=3.14V
Vnorm=3.3V
It must be provided
with sufficient current
up to 0.6A.
VIO 11 PI Power supply for
module’s I/O pins
Vmax=3.46V
Vmin=1.71V
Vnorm=1.8V
It is suggested to be
powered by
EC2x&EG2x-G
module.
GND
1, 12, 20,
28, 29,
31, 36,
38~40,
43~45,
48~52
Ground
Wi-Fi Interface
Pin Name Pin No. I/O Description DC Characteristics Comment
WAKE_ON_
WIRELESS 32 OD Wi-Fi wake up the host
VOLmax=0.18V
VOHmin=1.62V
1.8V power domain.
Active low.
Require external
pull-up to 1.8V.
If unused, keep this

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pin open.
WLAN_EN 9 DI Wi-Fi function
control
VILmin=-0.3V
VILmax=0.54V
VIHmin=1.26V
VIHmax=2.0V
1.8V power domain.
Active high.
SDIO_D3 22 IO SDIO data bus D3
VOLmax=0.18V
VOHmin=1.62V
VILmin=-0.3V
VILmax=0.54V
VIHmin=1.26V
VIHmax=2.0V
1.8V power domain
SDIO_D2 1) 23 IO SDIO data bus D2
VOLmax=0.18V
VOHmin=1.62V
VILmin=-0.3V
VILmax=0.54V
VIHmin=1.26V
VIHmax=2.0V
1.8V power domain.
Require external
pull-up to 1.8V.
SDIO_D1 24 IO SDIO data bus D1
VOLmax=0.18V
VOHmin=1.62V
VILmin=-0.3V
VILmax=0.54V
VIHmin=1.26V
VIHmax=2.0V
1.8V power domain
SDIO_D0 25 IO SDIO data bus D0
VOLmax=0.18V
VOHmin=1.62V
VILmin=-0.3V
VILmax=0.54V
VIHmin=1.26V
VIHmax=2.0V
1.8V power domain
SDIO_CLK 26 DI SDIO bus clock
VILmin=-0.3V
VILmax=0.54V
VIHmin=1.26V
VIHmax=2.0V
1.8V power domain
SDIO_CMD 27 IO SDIO bus command
VOLmax=0.18V
VOHmin=1.62V
VILmin=-0.3V
VILmax=0.54V
VIHmin=1.26V
VIHmax=2.0V
1.8V power domain
BT Interface
Pin Name Pin No. I/O Description DC Characteristics Comment

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BT_EN 10 DI BT function control
VILmin=-0.3V
VILmax=0.54V
VIHmin=1.26V
VIHmax=2.0V
1.8V power domain.
Active high.
If unused, keep this
pin open.
BT_WAKE_
HOST 46 OD BT wake up the host VOLmax=0.18V VOHmin=1.62V
1.8V power domain.
Active low.
Pulled up internally.
If unused, keep this
pin open.
PCM_IN 13 DI BT PCM data input
VILmin=-0.3V
VILmax=0.54V
VIHmin=1.26V
VIHmax=2.0V
1.8V power domain.
If unused, keep this
pin open.
PCM_SYNC 14 DI
BT PCM data frame
synchronization
signal
VILmin=-0.3V
VILmax=0.54V
VIHmin=1.26V
VIHmax=2.0V
1.8V power domain.
If unused, keep this
pin open.
PCM_CLK 15 DI BT PCM data bit
clock
VILmin=-0.3V
VILmax=0.54V
VIHmin=1.26V
VIHmax=2.0V
1.8V power domain.
If unused, keep this
pin open.
PCM_OUT 16 DO BT PCM data output VOLmax=0.18V
VOHmin=1.62V
1.8V power domain.
If unused, keep this
pin open.
BT_UART_
RTS 7 DO BT UART request to
send
VOLmax=0.18V
VOHmin=1.62V
1.8V power domain.
If unused, keep this
pin open.
BT_UART_
CTS 8 DI BT UART clear to
send
VILmin=-0.3V
VILmax=0.54V
VIHmin=1.26V
VIHmax=2.0V
1.8V power domain.
If unused, keep this
pin open.
BT_UART_
TXD 17 DO BT UART transmit
data
VOLmax=0.18V
VOHmin=1.62V
1.8V power domain.
If unused, keep this
pin open.
BT_UART_
RXD 18 DI BT UART receive
data
VILmin=-0.3V
VILmax=0.54V
VIHmin=1.26V
VIHmax=2.0V
1.8V power domain.
If unused, keep this
pin open.
Coexistence Interface
Pin Name Pin No. I/O Description DC Characteristics Comment
LTE_UART_
TXD 5 DO LTE/Wi-Fi&BT
coexistence signal
VOLmax=0.18V
VOHmin=1.62V
1.8V power domain.
If unused, keep this

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1. 1) indicates that SDIO_D2 is a boot strap signal, which must be kept at high level for normal
operation during power on.
2. 2) indicates that 32KHz_IN is reserved on FC21 module since the sleep function is still to be
developed.
pin open.
LTE_UART_
RXD 6 DI LTE/Wi-Fi&BT
coexistence signal
VILmin=-0.3V
VILmax=0.54V
VIHmin=1.26V
VIHmax=2.0V
1.8V power domain.
If unused, keep this
pin open.
RF Interface
Pin Name Pin No. I/O Description DC Characteristics Comment
RF_ANT 30 IO Wi-Fi/BT antenna
interface 50Ω impedance.
Other Interfaces
Pin Name Pin No. I/O Description DC Characteristics Comment
DBG_TXD 4 OD Used for software
debugging
VOLmax=0.18V
VOHmin=1.62V
1.8V power domain.
Require external pull-
up to 1.8V.
If unused, keep this pin
open.
32KHz_IN 2) 19 DI
Low power.
External 32.768kHz
clock input.
VILmin=-0.3V
VILmax=0.54V
VIHmin=1.26V
VIHmax=2.0V
1.8V power domain.
If unused, keep this pin
open.
RESERVED Pins
Pin Name Pin No. I/O Description DC Characteristics Comment
RESERVED
2, 3,
33~35,
37, 41,
42, 47
Reserved Keep these pins
open.
NOTES

Wi-Fi&BT Module Series
FC21 Hardware Design
FC21_Hardware_Design 19 / 52
3.4. Power Supply
3.4.1. Pin Introduction
The following table shows the power supply pins and the ground pins of FC21. The VIO power supply is
recommended to be powered by VDD_EXT of EC2x&EG2x-G modules.
Table 5: Power Supply Pins and GND Pins
FC21 is powered by VDD_3V3, and it is recommended to use a power supply chip with maximum output
current more than 0.6A.
The following figure shows a reference design for VDD_3V3. Pulling PM_ENABLE to a high voltage level
will enable VDD_3V3 power output. And this pin should be connected to pin 127 of EC2x&EG2x-G. For
more details, please refer to document [2], [3], [4], [5] or [6].
TPS630242
L1
L1
L2
L2
VIN
VIN
VIN
VINA
GND
EN
VOUT
VOUT
VOUT
PFM/PWM
FB
PGND
D2
D3
E1
E2
E3
E4
C4
D1 B1
A1
L1 L2
PGND
PGND
U402
D4
B2
B3
A2
A3
A4
B4
C1
C2
C3
C406
R408
C405
10 µF
1M
L401
1 µH
R407
100K
22 µF
C407
22 µF
PM_ENABLE
DC_5V
DC_5V
VDD_3V3
Figure 3: Reference Circuit for VDD_3V3
Pin Name Pin No. Description Min. Typ. Max. Unit
VDD_3V3 21 Main power supply for the
module 3.14 3.3 3.46 V
VIO 11 Power supply for the module’s
I/O pins 1.71 1.8 3.46 V
GND
1, 12, 20, 28,
29, 31, 36,
38~40,
43~45,
48~52
Ground
批注 [RL7]: 中文下面有个单独
的 3.4.1 引脚介绍，是否要加上