Nokia 5140 Manuales De Servicio

Nokia Customer Care

System Module and User Interface

NPL-4/5

Issue 1 05/04

Copyright © 2004 Nokia Corporation. All rights reserved.

Page 39

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.

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-

VANA 

R211, 12k 
5% 

R212, 68k 
1% 

R101,10k 
NTC 1% 

Headint2 

AuxDet 

UI board 

UEMEk 

A/D 
MUX 

Slow
ADC 

Parameter
Test conditions
Back-up battery 
voltage

VBACK

2.43

3.3

V

V_BU

COFF+

2.04

2.1

2.16

V

V_BU

COFF-

1.94

2

2.06

V

Charging voltage 
(VBAT 3.4V)

VBU

3.1

3.2

3.3

V

Charging current

I

LIMVBU

150

500

uA

Back-up battery 
cut-off limit