User Guide

PAMS
Technical Documentation
NSB–1
System Module
Original 06/98
Page 3 – 20
Sleep Mode
In the sleep mode all the regulators except the baseband VBB and the
SIM card VSIM regulators are off. Sleep mode is activated by the MAD
after MCU and DSP clocks have been switched off. The voltage regula-
tors for the RF section are switched off and the VCXO power control,
VCXOPwr is set low. In this state only the 32 kHz sleep clock oscillator in
CCONT is running. The flash memory power down input is connected to
the VCXO power control, so that the flash is deep powered down during
sleep mode.
The sleep mode is exited either by the expiration of a sleep clock counter
in the CCONT or by some external interrupt, generated by a charger con-
nection, key press, headset connection etc. The MAD starts the wake up
sequence and sets the VCXOPwr control high. After VCXO settling time
other regulators and clocks are enabled for active mode.
If the battery pack is disconnect during the sleep mode, the CCONT
should power down the SIM in the sleep mode as there is no time to wake
up the MCU.
Charging
The power management circuitry controls the charging current delivered
from the charger to the battery. Charging is controlled with a PWM input
signal, generated by the CCONT. The PWM pulse width is controlled by
the MAD and sent to the CCONT through a serial data bus. The battery
voltage rise is limited to a specified level by turning the switch off. Charg-
ing current is passed through protection ASIC CHAPS and monitored by
measuring the voltage drop across a 220mohm resistor.
2–wire charging
With 2–wire charging the charger provides constant output current, and
the charging is controlled by PWMOUT signal from CCONT to Charging
Logic. PWMOUT signal frequency is selected to be 1 Hz, and the charg-
ing switch in Charging Logic is pulsed on and off at this frequency. The
final charged energy to battery is controlled by adjusting the PWMOUT
signal pulse width.
Both the PWMOUT frequency selection and pulse width control are made
MCU which writes these values to CCONT.
3–wire charging
With 3–wire charging the charger provides adjustable output current, and
the charging is controlled by PWMOUT signal from CCONT to Charger,
with the bottom connector signal. PWMOUT signal frequency is selected
to be 32 Hz, and the charger output current is controlled by adjusting the
PWMOUT signal pulse width. The charger switch in Charging Logic is
constantly on in this case.