HUAWEI ME909s Series LTE Mini PCIe Module
Hardware Guide
Description of the Application Interfaces
Issue 02 (2016-09-07)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
28
Figure 3-12
Logic of USIM_DET
Modem
Processor
USIM Connector Switch
USIM installed=
Not Connected
USIM not
installed=
GND
WWAN Module
USIM_DET
1.8V
3.7.3
Circuit Recommended for the USIM Card Interface
As the Mini PCIe Adapter is not equipped with a USIM socket, you need to place a
USIM socket on the user interface board.
Figure 3-13 shows the circuit of the USIM card interface.
Figure 3-13
Circuit of the USIM card interface
USIM
Module
(DCE)
ESD protection
USIM-VCC
USIM-DET
USIM-CLK
USIM-DATA
USIM-RESET
1 µF
0 Ω
0 Ω
0 Ω
0 Ω
33 pF 33 pF
33 pF
33 pF
470 pF
1 kΩ
To meet the requirements of 3GPP TS 51.010-1 protocols and electromagnetic
compatibility (EMC) authentication, the USIM socket should be placed near the
PCIe interface (it is recommended that the PCB circuit connects the PCIe interface
and the USIM socket does not exceed 100 mm), because a long circuit may lead to
wave distortion, thus affecting signal quality.