Power Management - LG TracFone LG840G Service Manual

3. TECHNICAL BRIEF

3.6 Power management

GU295
3.6.1 Input power management
* Valid external supply attachment and removal detection
* Unregulated (closed-loop) external charger supply as input power source
* Integrated PFET charging pass transistor; eliminated sense resistor
* Support for lithium-ion and lithium-ion polymer main batteries; nickel-based batteries are not supported
* Trickle, constant current, constant voltage, and pulse charging of the main battery
* Autonomous charging option – driven by an on-chip state machine without software intervention
* Software-controlled charging option – backwards-compatible with previous QSC and PM products
* Coin-cell battery (including charging)
* Battery-voltage detectors with programmable thresholds
* VDD collapse protection
* Charger-current regulation and real-time monitoring for overcurrent protection
* Charger-transistor protection by thermal control
* Control drivers for the internal charging PFET and external battery PFET
* Voltage, current, and thermal control loops
* Automated recovery from sudden momentary power loss (requires external32.768 kHz crystal)
Figure 3.6.1 Input circuits schematic diagram
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