User's Manual

Table Of Contents

MC55/56 Hardware Interface Description

Confidential / Preliminary

MC55/56_hd_v03.00 Page 60 of 104 16.08.2005

3.11.2 Design considerations for SIM card holder

The schematic below is a sample configuration that illustrates the Molex SIM card holder

located on the DSB45 Support Box (evaluation kit used for type approval of the Siemens

MC55/56 reference setup, see [5]). X503 is the designation used for the SIM card holder in

[5].

Molex card holder

GSM module

Figure 20: SIM card holder of DSB45 Support Box

Table 16: Pin assignment of Molex SIM card holder on DSB45 Support Box

Pin no. Signal name I/O Function

1 CCVCC I Supply voltage for SIM card, generated by the GSM engine

2 CCRST I Chip card reset, prompted by the GSM engine

3 CCCLK I Chip card clock

4 CCGND - Individual ground line for the SIM card to improve EMC

5 CCVPP - Not connected

6 CCIO I/O Serial data line, bi-directional

7 CCDET1 - Connect to CCVCC

8 CCDET2 Connects to the CCIN input of the GSM engine. Serves to

recognize whether a SIM card is in the holder.

Pins 1 through 8 (except for 5) are the minimum

requirement according to the GSM Recommendations,

where pins 7 and 8 are needed for SIM card tray

detection through the CCIN pin.

Figure 21: Pin numbers of Molex SIM card holder on DSB45

Support Box

Place the capacitors C1205 and C1206 (or instead one capacitor of 200nF) as close as

possible to the pins 1 (CCVCC) and 4 (GND) of the card holder. Connect the capacitors to

the pins via low resistance tracks.