Baseband Electrical Interface: Dual Sim (For Rm-761 Only) - Nokia RM-761 Service Manual

RM-761; RM-799; RM-800
System Module
For ESD protection of the SIM interface signals, an integrated ESD/EMI suppression component is used. A 100nF
capacitor is located very close to the SIM card connector for supply decoupling. The Design of the X-Gold213
IO's ensures that all SIM signals are actively driven low as long as a valid battery voltage is present, even in
off mode, to comply with ISO7816-3 specifications.

Baseband electrical interface: Dual SIM (for RM-761 only)

Dual support in Quantum is implemented using a dedicated dual SIM interface IC, LFH1001 from Infineon.
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 a baseband IC 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.
Figure 62 Dual SIM using LFH1001
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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