Nokia 8550 Service Manual

NSM–3/3D

System Module

PAMS Technical Documentation

Page  19

Issue 4  02/2002

 Nokia Corporation

0.55

0.05 Vcc

0.85

0.05 Vcc

Vcc

GND

SIMC

ARD

D

ET

X

The battery temperature is measured with a NTC inside the battery pack.
The BTEMP line inside transceiver has a 100k pullup to VREF. The MCU
can calculate the battery temperature by reading the BTEMP line DC–
voltage level with a CCONT (N100) A/D–converter.

3

BTEMP

0

1.4

V

Battery temperature indication

100k pullup resistor to VREF in phone

Battery package has NTC pull down resis-

tor: 

47k +/–5%@+25C ,  B=4050+/–3%

2.1

5

10

3

20

V

ms

 Phone power up by battery (input)

 Power up pulse width

1.9

90

100

2.8

200

V

ms

 Battery power up by phone (output)

 Power up pulse width

–5

5

%

100k pullup resistor tolerance