Backup Battery; Sim Interface; Fig 9 Ambient Temperature Sensor Interface To Bb - Nokia NPL-4 Series Manual

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Backup battery

Backup battery is used in case when main battery is either removed or dis-charged.
Backup battery is used for keeping realtime clock running for minimum of 30 minutes.
Rechargeable backup battery is connected between UEMEK VBACK and GND. In UEMEK
backup battery charging high limit is set to 3.2V. The cut–off limit voltage (V BUCoff– )
for backup battery is 2.0V.
Backup battery charging is controlled by MCU by writing into UEM register. Li-Ion SMD
battery type is used. The nominal capacity of the battery is 0.01 mAh.
Parameter
Test conditions
Back-up battery
voltage
Back-up battery
cut-off limit
Charging voltage
(VBAT 3.4V)
Charging current

SIM interface

The UEMEK contains the SIM interface logic level shifting. The SIM interface can be pro-
grammed to support 3V and 1.8V SIM. A register in the UEMEK selects SIM supply volt-
Copyright © 2005 Nokia Corporation. All rights reserved.
Issue 2 05/05
Figure 9: Ambient Temperature Sensor Interface to BB
VANA
AuxDet
Headint2
UI board
Table 20: Backup Battery Circuitry
Symbol Min
VBACK 2.43
V_BU 2.04
COFF+
V_BU 1.94
COFF-
VBU 3.1
I 150
LIMVBU
System Module and User Interface
UEMEk
A/D
Slow
MUX
ADC
Typ Max
3.3
2.1 2.16
2 2.06
3.2 3.3
500
NPL-4/5/
Units
V
V
V
V
uA
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