Nokia 8850 Service Manual

NSM–2

System Module

PAMS Technical Documentation

Page  19

Issue 1  12/1999

 Nokia Mobile Phones Ltd.

There is a switched mode supply for SIM–interface. SIM voltage is se-
lected via serial IO. The 5V SMR can be switched on independently of the
SIM voltage selection, but can’t be switched off when VSIM voltage value
is set to 5V.

NOTE: VSIM and V5V can give together a total of 30mA.

In the next figure the principle of the SMR / VSIM–functions is shown.

V5V

CCONT

External

V5V_3

V5V_4

V5V_2

VBAT

5V

5V reg

VSIM

5/3V

The baseband is powered up by:

1.

Pressing the power key, that generates a PWRONX interrupt
signal from the power key to the CCONT, which starts the pow-
er up procedure.

2.

Connecting a charger to the phone. The CCONT recognizes
the charger from the VCHAR voltage and starts the power up
procedure.

3.

A RTC interrupt. If the real time clock is set to alarm and the
phone is switched off, the RTC generates an interrupt signal,
when the alarm is gone off. The RTC interrupt signal is con-
nected to the PWRONX line to give a power on signal to the
CCONT just like the power key.

4.

A battery interrupt. Intelligent battery packs have a possibility
to power up the phone. When the battery gives a short (10ms)
voltage pulse through the BTEMP pin, the CCONT wakes up
and starts the power on procedure.

When the charger is connected CCONT will switch on the CCONT digital
voltage as soon as the battery voltage exceeds 3.0V. The reset for