User's Guide

9
2.2.3. USIM interface
DWM-800A supports USIM card in UMTS mode as well as SIM card in GSM/GPRS/EDGE mode，and UIM card in
WCDMA mode.
2.2.3.1. Description
DWM-800A provides USIM card interface by MINI PCI-E which can be used in both UMTS and
GSM/GPRS/EDGE networks. The Table 2-3 gives more detailed information.
Table 2-3 DWM-800A USIM card interface description
Signals offered
by
USIM interface
The name of the correlative
pins in
MINI PCI-E
SN. of the MINI
PCI-E
Description
DATA
USIM_DATA
10
USIM card data
CLK
USIM_CLK
12
USIM card CLK
RST
USIM_RESET
14
Reset signal
VCC
VREG_EXTUSIM
8
USIM card power
GND
GND
4,9,15,18,21,26,27,29,34,3
5,37,43,50
GND
2.2.3.2. Reference circuit
The reference circuit of USIM interface is shown in Figure 2-6 below.
1) The DATA line of USIM is connected to SIM power supply by a pull-up resistor with reference value 15KΩ.
2) To avoid the instantaneous voltage overflowing, the resistor with reference value 22Ω can be used for the DATA,
CLK and RST line. Just like the resistors R307, R308 and R309 in Figure 2-6.
3) To avoid the static electricity in USIM socket, it is recommended to use the ESD protection device for the DATA，
CLK and VCC line. Just like the varistors RV301, RV302, RV303 and RV304 in Figure 2-6 this should be close to the
USIM socket as possible.
4) To get more flat USIM power supply, it is recommended to use the filter capacitors. Just like C311 and C312 in
Figure 2-6with reference value 33pF and 100nF.
5) To eliminate the peak interference and high frequency interference signal on RST and CLK line, the filter capacities
(C310, C309) can be placed in RST and CLK line, the reference value is 33pF.