HUAWEI MG323 GSM M2M Module
Description of the Application Interfaces
Issue 06 (2013-06-13)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
17
Table 3-2 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 supply 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
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 greatly 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, At least five 220 µF storage
capacitors should be connected in parallel at the power interface of the MG323
module. 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.
It is recommended to employ a ferrite bead in series on VBAT power circuit to
improve the EMI performance. And the rated current of the ferrite bead is required at
least 2 A.
Figure 3-2 shows the recommended power circuit of MG323 module.
Figure 3-2 Recommended power circuit of MG323 module
Module
(DCE)
VBAT
VBAT
100 nF
10 μF
+
220 μF
+
220 μF
+
220 μF
+
220 μF
+
220 μF
