Charging Circuitry - Nokia RM-11 Series Troubleshooting Manual

CC Technical Documentation

Charging Circuitry

The UEM controls charging depending on the charger being used and the battery size.
External components are needed for EMC, reverse polarity and transient protection of
the input to the baseband module. The charger connection is through the system
connector interface. The baseband is designed to support DCT3 chargers from an
electrical point of view. Both 2- and 3-wire type chargers are supported. However, as
mention above, three wire chargers are treated as two.
VCHAR
VCHAR in
Over temperature
detection
Watchdog
PWM generator
PWM
Issue 2 09/2005
UEM
Switch driver
Control logic
Figure 11: Charging circuitry
©2005 Nokia Corporation
Troubleshooting - Baseband
VCHAR out
Vmstr
Current
VBATT
sensing/limit
+
Comp
-
VBATT lim
Confidential
RM-11
VBATT
Battery
Page 25