LG E900 Service Manual page 42

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.
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3. TECHNICAL BRIEF
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