Huawei MC509 Series Hardware Manual page 26

HUAWEI MC509 Series CDMA 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 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 3-3 shows the connections of the POWER_ON_OFF and RESIN_N pins.
Figure 3-3 Connections of the POWER_ON_OFF and RESIN_N pins
Power-On Time Sequence
After VBAT has been applied and is stable, the module will generate an on board
power on reset signal and on the release of the reset, the module will boot up.
USB_DP will be pulled high when boot up completes, simultaneously the module
starts to communicate with host via USB or UART. Figure 3-4 shows power on timing
sequence.
During power on timing, please make sure the VBAT is stable.
Issue 02 (2013-05-06)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
Description of the Application Interfaces
26