NSB–6
System Module
PAMS Technical Documentation
Page 24
Issue 1 06/2000
E
Nokia Mobile Phones Ltd.
If the battery pack is disconnect during the sleep mode, the CCONT pulls
the SIM interface lines low as there is no time to wake up the MCU.
Charging
Charging can be performed in any operating mode.The battery type/size
is indicated by a resistor inside the battery pack. The resistor value corre-
sponds to a specific battery capacity. This capacity value is related to the
battery technology as different capacity values are achieved by using dif-
ferent battery technology.
The battery voltage, temperature, size and current are measured by the
CCONT controlled by the charging software running in the MAD.
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 by turning the CHAPS switch off when the battery
voltage has reached 4.2 V. Charging current is monitored by measuring
the voltage drop across a 220 mohm resistor.
Watchdog
The Watchdog block inside CCONT contains a watchdog counter and
some additional logic which are used for controlling the power on and
power off procedures of CCONT. The WD-counter runs during that time,
though. Watchdog counter is reset internally to 32 s at power up. Normal-
ly it is reset by MAD writing a control word to the WDReg.
