Patent ID: 8680719

Claim:
A direct current (DC) voltage supply apparatus, comprising: a voltage detection unit, for receiving and detecting a DC input voltage to generate an input voltage state signal, wherein the input voltage state signal indicates a stable state of the DC input voltage; an enable signal processing unit, coupled to the voltage detection unit, for receiving the input voltage state signal and an enable signal, and determining a state of the enable signal according to the input voltage state signal, wherein when the DC input voltage is stable, the enable signal is effective, and when the DC input voltage is unstable, the enable signal is ineffective; a latch unit, coupled to the enable signal processing unit, wherein when the enable signal is ineffective, the latch unit latches the enable signal to keep an ineffective state; a control unit, coupled to the enable signal processing unit and the latch unit, for receiving the enable signal to generate a control signal, wherein when the enable signal is effective, the control signal is effective, and when the enable signal is ineffective, the control signal is ineffective; and a voltage transforming unit, coupled to the control unit, wherein when the control signal is effective, the voltage transforming unit receives the DC input voltage and transforms the DC input voltage into a DC output voltage for outputting, and when the control signal is ineffective, the voltage transforming unit stops receiving the DC input voltage.