Huawei MU509 Series Hardware Manual page 32

HUAWEI MU509 Series HSDPA LGA Module
Hardware Guide
As the RESIN_N and POWER_ON_OFF signals are relatively sensitive, it is
recommended that you install a 10 nF capacitor near the RESIN_N and
POWER_ON_OFF pins of the interface for filtering. In addition, when you design a
circuit on the PCB of the interface board, it is recommended that the circuit length not
exceed 20 mm and that the circuit be kept at a distance of 2.54 mm (100 mil) at least
from the PCB edge. Furthermore, you need to wrap the area adjacent to the signal
wire with a ground wire. Otherwise, the module may be reset due to interference.
Figure 3-4 Connections of the POWER_ON_OFF and RESIN_N pins
Power-On Time Sequence
After VBAT has been applied and is stable, the POWER_ON_OFF signal is pulled
down, and then the module will boot up.
During power on timing, please make sure the VBAT is stable.
Issue 09 (2014-03-06)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
Description of the Application Interfaces
32