Ir Module; Backup Battery; Sim Interface - Nokia NHM-7 series Service Manual

PAMS Technical Documentation

IR Module

The IR interface, when using 2.7V transceiver, is designed into the UEM.
The IR link supports speeds from 9600 bit/s to 1.152 MBit/s up to dis-
tance of 1m. Transmission over the IR if half–duplex.
The lenght of the transmitted IR pulse depends on the speed of the trans-
mission. When 230.4 kbit/s or less is used as a transmission speed, pulse
length is maximum 1.63us. If transmission speed is set to 1.152Mbit/s the
pulse length is 154ns according to IrDA specification.

Backup Battery

Backup battery is used in case when main battery is either removed or
discharged. Backup battery is used for keeping real-time clock running for
minimum of 30 minutes.
Rechargeable backup battery is connected between UEM VBACK and
GND. In UEM backup battery charging high limit is set to 3.2V. The cut–
off limit voltage (V
charging is controlled by MCU by writing into UEM register.
Polyacene SMD battery type is used. The nominal capacity of the battery
is 0.2 mAh.

SIM Interface

UEM contains the SIM interface logic level shifting. SIM interface can be
programmed to support 3V and 1.8V SIMs. SIM supply voltage is se-
lected by a register in the UEM. It is only allowed to change the SIM sup-
ply voltage when the SIM IF is powered down.
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 sig-
nal, 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 do 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.
Parameter
SIMCARDet, BSI comparator Threshold
SIMCARDet, BSI comparator Hysteresis (1)
The whole SIM interface locates in two chip 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).
Issue 1 10/2001
) for backup battery is 2.0V. Backup battery
BUCoff–
Variable
Vkey
Vsimhyst
E Nokia Corporation
System Module & UI
Min Typ Max
1.94 2.1 2.26
50 75 100
NHM–7
Unit
V
mV
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