Battery Removal During Charging - Nokia NSB-5 Series Technical Documentation Manual

NSB-5
System Module
When the switch in output overvoltage situation has once turned OFF, it stays OFF until
the the battery voltage falls below VLIM1 (or VLIM2) and PWM = LOW is detected. The
switch can be turned on again by setting PWM = HIGH.
VCH
VCH<VOUT
VOUT
VLIM1 or VLIM2
SWITCH
PWM (32Hz)

Battery Removal During Charging

Output overvoltage protection is also needed in case the main battery is removed when
charger connected or charger is connected before the battery is connected to the phone.
With a charger connected, if VOUT exceeds VLIM1 (or VLIM2), CHAPS turns switch OFF
until the charger input has sunken below Vpor (nominal 3.0V, maximum 3.4V). MCU soft-
ware will stop the charging (turn off PWM) when it detects that battery has been
removed. The CHAPS remains in protection state as long as PWM stays HIGH after the
output overvoltage situation has occurred.
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