LG KS20 Operating Instructions Manual page 42

3. TECHNICAL BRIEF
3.9.3. Charging control
A programmable charging block in PM7540 is used for battery charging. It is possible to set limits for
the charging current. The external supply typically connects directly to pin (VCHG). The voltage on this
pin (VCHG) is monitored by detection circuitry to ascertain whether a valid external supply is applied or
not. For additional accuracy or to capture variations over time, this voltage is routed internally to the
housekeeping ADC via the analog multiplexer. PM7540 circuits monitor voltages at VCHARGER and
ICHARGE pins to determine which supply should be used and when to switch between the two
supplies. These pins are connected to the Source (or emitter) and Drain (or collector) contacts of the
pass transistor respectively.
100~76 (%)
LGE Internal Use Only
50~26 (%)
75~51 (%)
KS20 Battery Bar Display(Stand By Condition)
- 44 -
Input Power
Management
5~0 (%)
25~6 (%)
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
PM7540