Nokia 8850 Service Manual

NSM–2

System Module

PAMS Technical Documentation

Page  21

Issue 1  12/1999

 Nokia Mobile Phones Ltd.

VBB (2.8V)

CCPURX

PURX

Vchar

1 2

3

1:Power switch pressed ==> Digital voltages on in CCONT (VBB)
2: CCONT digital reset released. VCXO turned on
3: 62 ms delay to see if power switch is still pressed.

VR1,VR6

SLEEPX

PWRONX

RTC (internal in CCONT) can power the phone up by changing RTCPwr
to logical 1.

IBI can power CCONT up by giving a short pulse (10ms) through the
BTEMP line. After powerup BTEMP will act as any other input channel for
ADC.

When the PURX reset is released, the MAD releases the system reset
ExtSysResetX and the internal MCUResetX signals and starts the boot
program execution from MAD bootrom if MAD GenSDIO pin is pulled low
or from external memory if GenSDIO pin is pulled high. In normal opera-
tion the program execution continues from the flash program memory. If
the MBUS line is pulled low during the power up the bootrom starts a
flash programming sequence and waits for the prommer response
through FBUS_RX line.

The baseband is powered down by:

1.

Pressing the power key, that is monitored by the MAD, which
starts the power down procedure.

2.

If the battery voltage is dropped below the operation limit, ei-
ther by not charging it or by removing the battery.

3.

Letting the CCONT watchdog expire, which switches off all
CCONT regulators and the phone is powered down.