Patent ID: 7541786

Claim:
A voltage regulator, comprising: a voltage regulation unit for comparing a voltage corresponding to an output voltage outputted form the voltage regulation unit with an input voltage and regulating the output voltage according to a first comparison result between the voltage corresponding to the output voltage and the input voltage; and an over driving unit, coupled between an input terminal and an output terminal of the voltage regulation unit, and regulating the input voltage according to a second comparison result between the output voltage and a reference voltage, wherein the over driving unit comprises: a voltage comparison circuit, coupled to the output terminal of the voltage regulator for comparing the output voltage of the voltage regulator and a reference voltage and outputting an over driving signal; an over driving circuit, coupled between the voltage comparison circuit and the input terminal of the voltage regulation unit, and regulating the input voltage of the voltage regulation unit according to the over driving signal, wherein the over driving circuit comprises: a current source; a first resistor and a second resistor, coupled in series between the current source and a ground terminal; a first switch with one terminal coupled to the common node of the current source and the first resistor, and another terminal coupled to the output terminal of the over driving circuit; and a second switch with one terminal coupled to the common node of the first resistor and the second resistor, and another terminal coupled to the output terminal of the over driving circuit, wherein when the output voltage is higher than the reference voltage, the first switch is opened and the second switch is closed; when the output voltage is lower than the reference voltage, the first switch is closed and the second switch is opened; and the output terminal of the over driving circuit outputs the input voltage of the voltage regulation unit.