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Hardware Development Guide of Module Product
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18
ZTE MG2618
4.3
SIM Card Interface
Module supports two kinds of SIM card of 1.8V and 3V. The following Figure shows the reference
design of the SIM card. On the line close to the SIM card console, be sure to add the ESD circuit protection
during the design.
Table 4
–
3 Definition of SIM Card Signal
PIN
Function
Definition
I/O
Description
Remark
21
SIM
VREG_SIM
O
SIM card power, output
from the module
1.8/3V
22
SIM
SIM_DATA
I/O
SIM card DATA signal
--
23
SIM
SIM_CLK
O
SIM card clock signal
--
24
SIM
SIM_RST
O
SIM card reset signal
--
The typical rate of SIM card interface is about 3.25MHz. It is recommended to place SIM card
console close to the SIM card interface to prevent the wiring from being too long(less than 100mm), which
might seriously distort the waveform and thus affect the signal integrity
The distance between the module and headset/handset should be as shor
t as possible and it’s
enveloped by the ground wires to avoid strong interference sources.
It is recommended to make the grounding protection for SIM_CLK and SIM_DATA signal wiring.
Cascade one 1uF capacitor between VREG_SIM and GND, another 0.1uF and 33pF capacitor can be
added between VREG_UIM and GND. In order to filter out the
antenna’s
interference signal, add three
33pF capacitors between SIM_CLK, SIM_DATA, SIM_RST and GND.
It is recommended to take electrostatic discharge (ESD) protection measures near the SIM card socket.
The TVS diode junction capacitance less than 10 pF must be placed as close as possible to the SIM socket,
and the Ground pin of the ESD protection component is well connected to the Ground. The recommended
model is: CESDLC3V0L4//NZQA5V6AXV5T1G//PESD3V3V4UW. The reference circuit of SIM card
interface is as shown in Figure below.