Nokia 8550 Service Manual
NSM–3/3D
System Module
System Module
PAMS Technical Documentation
Page 22
Issue 4 02/2002
Nokia Corporation
CCONT’s digital parts is released when the operating voltage is stabilized
( 50 us from switching on the voltages). Operating voltage for VCXO is
also switched on. The counter in CCONT digital section will keep MAD in
reset for 62 ms (PURX) to make sure that the clock provided by VCXO is
stable. After this delay MAD reset is relased, and VCXO –control
(SLEEPX) is given to MAD. The next diagram explains the power on pro-
cedure with charger ( the picture assumes empty battery, but the situation
would be the same with full battery):
( 50 us from switching on the voltages). Operating voltage for VCXO is
also switched on. The counter in CCONT digital section will keep MAD in
reset for 62 ms (PURX) to make sure that the clock provided by VCXO is
stable. After this delay MAD reset is relased, and VCXO –control
(SLEEPX) is given to MAD. The next diagram explains the power on pro-
cedure with charger ( the picture assumes empty battery, but the situation
would be the same with full battery):
Vbat
VBB (2.8V)
CCPURX
PURX
Vchar
1 2
3
1: Battery voltage over 3.0==>Digital voltages to CCONT (VBB)
2: CCONT digital reset released. VCXO turned on
3: 62ms delay before PURX released
2: CCONT digital reset released. VCXO turned on
3: 62ms delay before PURX released
VR1
SLEEPX
VR6
Vref
When the phone is powered up with an empty battery pack using the
standard charger, the charger may not supply enough current for stan-
dard powerup procedure and the powerup must be delayed.
standard charger, the charger may not supply enough current for stan-
dard powerup procedure and the powerup must be delayed.
Power Up With The Power Switch (PWRONX)
When the power on switch is pressed the PWRONX signal will go low.
CCONT will switch on the CCONT digital section and VCXO as was the
case with the charger driven power up. If PWRONX is low when the 64
ms delay expires, PURX is released and SLEEPX control goes to MAD. If
PWRONX is not low when 64 ms expires, PURX will not be released, and
CCONT will go to power off ( digital section will send power off signal to
analog parts)
CCONT will switch on the CCONT digital section and VCXO as was the
case with the charger driven power up. If PWRONX is low when the 64
ms delay expires, PURX is released and SLEEPX control goes to MAD. If
PWRONX is not low when 64 ms expires, PURX will not be released, and
CCONT will go to power off ( digital section will send power off signal to
analog parts)