NSW-6
System Module SE2
PAMS Technical Documentation
Page 19
Issue 1 12/99
Nokia Mobile Phones Ltd.
Clocking
System Clock
. Clocking and resets
CCONT
BATTERY
VCXO
MAD
COBBA
LCD–DRVR
19.44MHz
200mVpp–1Vpp
sine wave
9.72MHz
Square wave
2.8Vpp
SLCLK
PURX
RFCEN
VR1
COBBARESX
PWRONX
LCDRESX
RFC
COBBACLK
CHAPS
32 kHz
RFCSETTLED
VCXO on RF provides the system clock for baseband (RFC). COBBA
squares the clock and divides it by two for MAD (COBBACLK).
This clock can be stopped by cutting supply voltage from VCXO (CCONT
regulator VR1) and started again by powering on the same regulator.
MAD controls it through RFCEN. It can be stopped only when both MCU
and DSP request that. It is always stopped in SLEEP–mode on control
channels. When the VCXO is stopped time is measures in MAD by using
the sleep clock SLCLK; when the programmable timer expires it gives in-
terrupt to DSP/MCU and MAD also starts the VCXO power supply by
RFCEN signal.
The same sleep clock is also used in the MBUS interface, to detect if
there is communication on the bus during sleep periods.
Inside MAD System Logic parts provide clock signal to both DSP and
MCU, and both internal clocks can be stopped individually for power sav-
ing. MCU can use either CLOCK STOP or HW STANDBY sleep mode.
Sleep Clock
CCONT makes 32.768 kHz sleep clock for MAD. This crystal oscillator in
CCONT_2’ starts to run only after the battery is connected and the phone