Chapter 3 – Electrical Characteristics
Wireless ModemModule MTMMC-G-F1 and MTMMC-G-F2 Developer’s Guide
29
SIM interface
The external SIM interface is available through the 50-pin connector in order to use a stand-alone SIM
cardholder. 5V SIMs can be driven using an external level shifter.
SIM line must not exceed 15 cm. See also the “Hardware and RF” section of
Chapter 5: Application
Considerations
.
Five signals are available:
SIMVCC: SIM power supply.
SIMRST: reset.
SIMCLK: clock.
SIMDATA: I/O port.
SIMPRES1 SIM card detect. This signal is connected to the external SIM connector on pin 8. Pin 4 of SIM
connector must be pulled down to GND with 1
K
.
This interface is fully compliant with GSM 11.11 recommendations concerning the SIM functionality.
Transient Voltage Suppressor diodes are internally added on the signals connected to the SIM socket in order to
prevent any Electro-Static Discharge. TVS diodes with low capacitance (less than 10pF) are connected on
SIMCLK and SIMDATA to avoid any disturbance of the rising and falling edge.
Table 3-23: SIM Interface Pin Description
Signal
Pin Number
I/O
I/O Type*
Description
SIMCLK
45
O
2X
SIM Clock
SIMRST
46
O
2X
SIM Reset
SIMDATA
49
I/O
CMOS/2X
SIM Data
SIMVCC
47
O
SIM Power Supply
SIMPRES1
48
I
CMOS
SIM Card Detect
GPO0
50
O
2X
SIM 3V or 5V
* See “Table 3-2: Operating Conditions” in section on the
50-pin Connector Description
.
The SIM schematic appears later in this chapter.