User Guide

NPM-10 (3595)

System Module CC Technical Documentation

Figure 5: Overview of LCD module SIM Interface

SIM Interface

The UEM contains the SIM interface logic level shifting. The SIM supports 3 V and 1.8 V

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 the

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 the UEM. The

comparator offset is such that the comparator output does not alter the state as long as

the battery is connected. The threshold voltage is calculated from the battery size speci-

fications.

The SIM interface is powered up when the SIMCardDet signal indicates ”card in”. This

signal is derived from the BSI signal.

(1)

Hysteresis is defined as [Vkey(+)-Vkey(-)] / 2

Table 23: BSI Detection

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