Figure 57 RAPGSM/Retu SIM interface connections
SIM Logic level shifting
The SIM interface can be programmed to support 3V and 1.8V SIM cards. Retu contains a SIM interface called
Logic level shifting. A register in Retu selects the supply voltage when the SIM interface is powered down.
SIM Power up/down
The SIM power up/down sequence is generated in Retu. This means that Retu generates the reset switch
(RST) signal to the SIM. In addition, the SIMCardDet signal is connected to Retu. The card detection is taken
from the SIMCarDet signal. A comparator inside Retu does the monitoring of the SIMCarDet signal. The
comparator outputs do not alter state as long as the battery is connected.
The SIM interface is powered up when the SIMCardDet signal indicates “card in”.
RM-70
Nokia Customer Care System module
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