Nokia 301 Service Manual page 156

RM-839; RM-840; RM-841
System Module
Figure 46 SIM connectors
The dual SIM interface is done by an external component (LFH1001). The LFH1001 is a dual SIM card interface
IC for use in mobile stations. It has two LDOs to provide power conversion for 1.8V and 3.0V and three level
shifters per SIM card for signal level translation. The LFH1001 interfaces between X-GOLD614 single ISO/IEC
7816-3/UICC compliant SIM interface, and two SIM cards. The LFH1001 multiplexes the signal paths of the two
SIM cards so that one will be connected to the SIM interface in the baseband IC, while the other is left in clock
stop mode. This allows both SIM cards to be powered and provides a flexible and efficient way of switching
between the two cards without having to execute repeated de-activation and activation sequences in order
to access the two cards. The LFH1001 has an integrated detection of SIM card presence based on two
application concepts:
• Battery detection in case one or both SIM cards are located behind the battery
• Contact detection in an external card reader, in case one SIM is located in a directly user accessible slot
The LFH1001 contains logic for detecting the state of the SIM cards and performing automatic shutdown of
the SIM interface signals in case removal of the card is detected.
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