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HUAWEI MG323 GSM M2M Module
Hardware Guide
Description of the Application Interfaces
Issue 04 (2011-08-22)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
13
3.3 Power Interface
3.3.1 Overview
The power supply part of the B2B interface of the MG323 module contains:
VBAT interface for the power supply
VCOIN interface for the standby power supply of the real-time clock (RTC)
VIO interface for external power output
Table 3-1 lists the definitions of the pins on the power supply interface.
Table 3-1 Definitions of the pins on the power supply interface
Pin No.
Signal Name
I/O
Description
42, 44, 46, 48, 50
VBAT
P
Pins for power voltage input
41, 43, 45, 47, 49
GND
-
GND
35
VCOIN
P
Pin for standby power input of
the RTC
40
VIO
P
Pin for external power output
P indicates power pins; I indicates pins for digital signal input; O indicates pins for digital signal
output; AI indicates pins for analog signal input; AO indicates pins for analog signal input.
3.3.2 VBAT Interface
When the MG323 module works normally, power is supplied through the VBAT pins
and the voltage ranges from 3.3 V to 4.8 V (typical value: 3.8 V). The 50-pin B2B
connector provides five VBAT pins and five GND pins for external power input. To
ensure that the MG323 module works normally, all the pins must be used efficiently.
When the MG323 module is used for different external applications, pay special
attention to the design for the power supply. When the MG323 module transmits
signals at the maximum power, the transient current may reach the transient peak
value of about 2.0 A due to the differences in actual network environments. In this
case, the VBAT voltage drops. Make sure that the voltage does not decrease below
3.3 V in any case. Otherwise, exceptions such as restart of the MG323 module may
occur.
A low-dropout (LDO) regulator or switch power with current output of more than 2 A is
recommended for external power supply. Furthermore, a 2.2 mF or above energy
storage capacitor is connected in parallel at the power interface of the MG323
module. As for the energy storage capacitor, a 2.2 mF or above electrolytic capacitor
is recommended. In addition, to reduce the impact of channel impedance on voltage
drop, you are recommended to try to shorten the power supply circuit of the VBAT
interface.