Patent ID: 8248049
Filing Date: 2012-08-21
Classification: H02J

Abstract:
1. A linear charger comprising: a power input terminal to receive an input voltage; a power output terminal to provide an output voltage; a charging NMOSFET having a drain coupled to the power input terminal, a source coupled to the power output terminal, and a gate controlled by a driving voltage to generate a charging current; a sensing NMOSFET common gated with the charging NMOSFET; a current setting/sensing circuit coupled between the power output terminal and a source of the sensing NMOSFET, to virtually short the power output terminal to the source of the sensing NMOSFET, to thereby have the charging NMOSFET and sensing NMOSFET applied with a same gate-source voltage, for the sensing NMOSFET to reflect the charging current on its drain-source current to provide a current sensing signal accordingly; a loop controller coupled to the current setting/sensing circuit, to generate a control signal according to the current sensing signal; a driver coupled to the loop controller and the gate of the charging NMOSFET, to supply the driving voltage according to the control signal; and a voltage generator coupled to the driver, the voltage generator supplying a voltage to the driver to generate the driving voltage, wherein the voltage generated by the voltage generator is higher than the output voltage.