Sim Card Reader Integration; Layout Restrictions - Altec AL7020S Series Designer’s guide Designer's Manual

3.7.3 SIM Card Reader Integration:

SIM interface controls a 3V SIM only.
We add Transient Voltage Suppressor (TVS) diodes with low capacitance (less than
10pF) on signal connected to the SIM socket in order to prevent any Electrostatic
Discharge. They shall be placed as close as possible to the SIM socket. Following
references are used:
DALC208SC6 from ST Microelectronics, which will be connected, to SIMCLK and
SIMDATA.
ESDA6V1 from ST Microelectronics for the ESD protection of SIMVCC.
On the board near SIM connector, we also add on SIMVCC a 100nF capacitor in
parallel as close as possible to the SIM connector to minimize noise.
Schematic of SIM Interface:
PRES_OUT
SIM-CARD-READER
P1
D1
ESDA6V1L

3.7.4 Layout Restrictions:

For the SIM interface, length of the tracks between the GSM modem and the SIM
connector should be as short as possible (8cm).
EMI layout is recommended for SIMCLK signal.
SIM
connector
Doc. No. DG_7024E
AL7020S, AL7024S Designer's Guide
8
4
PRES_IN
7
I/O
6
VPP
5
GND
3
CLK
2
RST
1
VCC
C1
100NF
SIMCLK
SIMRST
SIMVCC
SIMDATA
GND
Altec Electronic AG
SIMDATA
SIMCLK
SIMRST
SIMVCC
D2
GND
GND
Less than 8 cm
32
31
30
29
28
27
26
25
24
SOCKET MODEM
RESET
Socket
Modem
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