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SIM Interface
The Subscriber Identification Module can be directly connected to the WISMO228 through this
dedicated interface.
This interface controls both 1.8V and 3V SIM cards and is fully compliant with GSM 11.11
recommendations concerning SIM functions.
The SIM uses four signals, namely:
•
SIM‐VCC: SIM power supply
•
~SIM‐RST: reset
•
SIM‐CLK: clock
•
SIM‐IO: I/O port
It is recommended to add Transient Voltage Suppressor (TVS) diodes on the signals connected to
the SIM socket in order to prevent any Electrostatic Discharge. TVS diodes with low capacitance
(less than 10pF) have to be connected on the SIM‐CLK and SIM‐IO signals to avoid any disturbance
from the rising and falling edge of the signals. TVS diodes are mandatory for the Full Type
Approval and they must be placed as close to the SIM socket as possible.
The recommended low capacitance diode array to use is the DALC208SC6 from ST Microelectronics.
Electrical Characteristics
The following table describes the electrical characteristics of the SIM interface.
Parameters
SIM-IO VIH
SIM-IO VIL
~SIM-RST, SIM-CLK
VOH
SIM-IO VOH
~SIM-RST, SIM-IO, SIM-
CLK
VOL
SIM-VCC Output Voltage
WA_DEV_W228_PTS_002
Table 12. Electrical Characteristics of the SIM Interface
Conditions
IIH = ± 20µA
IIL = 1mA
Source current = 20µA
Source current = 20µA
Sink current =
-200µA
SIM-VCC = 2.9V
Rev 001
Product Technical Specification &
Customer Design Guidelines
Minimum
Typical
0.7xVSIM
-
-
-
0.9xVSIM
-
0.8xVSIM
-
-
-
2.75
2.9
Maximum
Unit
-
V
0.4
V
-
V
-
V
0.4
V
3.0
V
Page 48 of 108
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