HUAWEI ME909 Series LTE LGA Module
Hardware Guide
Description of the Application Interfaces
Issue V0.3 (2013-05-21)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
23
Pin No.
Signal
Name
I/
O
Description
DC Characteristics (V)
Min. Typ.
Max.
48
–50, 52–54,
56
–59, 106,
108, 110, 112,
114, 116
GND
-
GND
-
-
-
32
VCC_EXT1 P
Pin for external
power output
1.75
1.8
1.85
34
SIM_VCC
P
Power supply
for USIM card
-
1.8/2.85 -
121
–145
GND
-
Thermal
Ground Pad
-
-
-
3.3.2
Power Supply VBAT Interface
When the ME909 module works normally, power is supplied through the VBAT pins
and the voltage ranges from 3.3 V to 4.2 V (typical value: 3.8 V). The 145-pin LGA
provides 2 VBAT pins and 41 GND pins for external power input. To ensure that the
ME909 module works normally, all the pins must be used efficiently.
When the ME909 module is used for different external applications, pay special
attention to the design for the power supply. When the ME909 module works at 2G
mode and transmits signals at the maximum power, the transient current may reach
the transient peak value of about 2.5 A due to the differences in actual network
environments. In this case, the VBAT voltage drops. If you want wireless good
performance, please make sure that the voltage does not decrease below 3.3 V in any
case. Otherwise, exceptions such as restart of the ME909 module may occur.
A low-dropout (LDO) regulator or switch power with current output of more than 2.5 A
is recommended for external power supply. Furthermore, five 220 µF or above energy
storage capacitors
are connected in parallel at the power interface of the ME909
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 that customer add the EMI ferrite bead (NR3015T4R7M
manufactured by TAIYO YUDEN or VLS3015T-4R7MR99 manufactured by TDK is
recommended) to directly isolate DTE from DCE in the power circuit. Figure 3-3
shows the recommended power circuit of ME909 module.
