Motorola D10 Service Manual page 73

BenQ Rev 1.0
ICTL. F1 is a 1A fuse to assure charging current under safe limit.
The normal charging operation theory is that Nausica monitors charger
voltage via VCHG pin to decide whether adaptor plug in or not, and
control power P-MOSFET (U12) via ICTL pin. If phone enters into
charging mode, Ulysse will follow the charging algorithm to control
charging circuit and monitor charging current by detecting the terminal
voltage of R24 (0.2 ohm). Nausica BCI & Voltage detector(U17) is
used to limit the charging currents, for lasting battery life, when battery
voltage is lower than 3.2V. Nausica will execute trickle charge about
30mA to charge battery via VCHG pin if battery voltage is lower than
3.2V. Charger IC (U11) is in charge of mainly charging task. While
battery voltage between 3.2V to 4.2V, Charging current is set to 420mA.
When battery voltage reaches 4.2V, the charging IC will change its
mode from constant-current to constant-voltage. After that, charging will
be stopped if charging current is decreasing from 420mA to 30mA.
32