Nokia 8850 Service Manual
NSM–2
System Module
System Module
PAMS Technical Documentation
Page 18
Issue 1 12/1999
Nokia Mobile Phones Ltd.
Supply Voltage Regulators
The heart of the power distrubution is the CCONT. It includes all the volt-
age regulators and feeds the power to the whole system. The baseband
digital parts are powered from the VBB regulator which provides 2.8V
baseband supply. The baseband regulator is active always when the
phone is powered on. The VBB baseband regulator feeds MAD and me-
mories, COBBA digital parts and the LCD driver in the UI section. There is
a separate regulator for a SIM card. The regulator is selectable between
3V and 5V and controlled by the SIMPwr line from MAD to CCONT. The
COBBA analog parts are powered from a dedicated 2.8V supply VCOB-
BA. The CCONT supplies also 5V for RF and for flash VPP. The CCONT
contains a real time clock function, which is powered from a RTC backup
when the main battery is disconnected. The RTC backup is rechargable
polyacene battery. The battery is charged from the main battery voltage
by the CHAPS when the main battery voltage is over 3.2V.
age regulators and feeds the power to the whole system. The baseband
digital parts are powered from the VBB regulator which provides 2.8V
baseband supply. The baseband regulator is active always when the
phone is powered on. The VBB baseband regulator feeds MAD and me-
mories, COBBA digital parts and the LCD driver in the UI section. There is
a separate regulator for a SIM card. The regulator is selectable between
3V and 5V and controlled by the SIMPwr line from MAD to CCONT. The
COBBA analog parts are powered from a dedicated 2.8V supply VCOB-
BA. The CCONT supplies also 5V for RF and for flash VPP. The CCONT
contains a real time clock function, which is powered from a RTC backup
when the main battery is disconnected. The RTC backup is rechargable
polyacene battery. The battery is charged from the main battery voltage
by the CHAPS when the main battery voltage is over 3.2V.
Operating mode
Vref
RF REG
VCOBBA
VBB
VSIM
SIMIF
Power off
Off
Off
Off
Off
Off
Pull
down
down
Power on
On
On/Off
On
On
On
On/Off
Reset
On
Off
VR1 On
VR1 On
On
On
Off
Pull
down
down
Sleep
On
Off
Off
On
On
On/Off
NOTE:
COBBA regulator is off in SLEEP mode. Its output pin may be fed
from V
from V
BB
in SLEEP mode by setting bit RFReg(5) to ’1’ (default).
CCONT includes also five additional 2.8V regulators providing power to
the RF section. These regulators can be controlled either by the direct
control signals from MAD or by the RF regulator control register in
CCONT which MAD can update. Below are the listed the MAD control
lines and the regulators they are controlling.
the RF section. These regulators can be controlled either by the direct
control signals from MAD or by the RF regulator control register in
CCONT which MAD can update. Below are the listed the MAD control
lines and the regulators they are controlling.
– TxPwr controls VTX regulator (VR5)
– RxPwr controls VRX regulator (VR2)
– SynthPwr controls all the rf regulators except VR1
– VCXOPwr controls VXO regulator (VR1)
In additon to the above mentioned signals MAD includes also TXP control
signal which goes to HAGAR power control block. The transmitter power
control TXC is led from COBBA to HAGAR.
signal which goes to HAGAR power control block. The transmitter power
control TXC is led from COBBA to HAGAR.