User Guide

PAMS Technical Documentation System Module & UI
NHM-8NX
Issue 1 05/02 ãNokia Corporation Page 31
and V
IO
for the driver chip.
SIM Interface
The UEM contains the SIM interface logic level shifting. The SIM supports 3V and 1.8V
SIMs. SIM supply voltage is selected by a register in the UEM. It is only allowed to
change the SIM supply voltage when the SIM IF is initialized.
The SIM power up/down sequence is generated in the UEM. This means that the UEM
generates the RST signal to the SIM. Also the SIMCardDet signal is connected to UEM.
The card detection is taken from the BSI signal, which detects the removal of the battery.
The monitoring of the BSI signal is done by a comparator inside UEM. The comparator
offset is such that the comparator output does not alter state as long as the battery is
connected. The threshold voltage is calculated from the battery size specifications.
The SIM interface is powered up when the SIMCardDet signal indicates ”card in”. This
signal is derived from the BSI signal.
Table 26: BSI Detection
Note: (1) Hysteresis is defined as [Vkey(+)-Vkey(-)] / 2
Figure 6: BSI Detection
The whole SIM interface is located in the two ASICs, UPP and UEM.
The SIM interface in the UEM contains power up/down, port gating, card detect, data
receiving, ATR-counter, registers and level shifting buffers logic. The SIM interface is the
electrical interface between the Subscriber Identity Module Card (SIM Card) and mobile
phone (via UEM device).
Parameter Variable Min Typ Max Unit
BSI comparator Threshold Vkey 1.94 2.1 2.26 V
BSI comparator Hysteresis (1) Vsimhyst 50 75 100 mV
GND
BSI
V
FLASH1
Example of BSI detection
Vkey
Vkey(+)
Vkey(-)