Power supply apparatus and power supplying method thereof

1. A power supply apparatus comprising:

a power switch receiving a first power and a second power respectively through a first switch and a second switch; and

a supplied power generator coupled to the power switch, receiving and performing a voltage converting operation to the first power or the second power to generate a supplied power,

wherein, the first switch is turned on and the second switch is cut off and the supplied power generator performs the voltage converting operation to the first power,

when the supplied power generator judges the first power as being cut off, during a first period, the first switch is cut off and the supplied power generator stops the voltage converting operation; during a second time period, the second switch is turned on and after the second switch being turned on, the supplied power generator restarts the voltage converting operation to generate the supplied power, where the first time period is before the second time period.

2. The power supply apparatus according claim 1 , wherein the supplied power generator transmits a power abnormal signal when the first power is cut off.

3. The power supply apparatus according to claim 2 , wherein the supplied power generator stops the voltage converting operation according to the power abnormal signal.

4. The power supply apparatus according to claim 3 , wherein the power abnormal signal is transmitted to a system terminal, and the system terminal transmits a power on/off signal to the supplied power generator according to the power abnormal signal, and makes the supplied power generator stop the voltage converting operation according to the power on/off signal.

5. The power supply apparatus according to claim 4 , wherein the supplied power generator stops transmitting the power abnormal signal when the second switch is turned on and the supplied power generator receives the second power.

6. The power supply apparatus according to claim 5 , wherein the supplied power generator restarts the voltage converting operation after stopping transmitting the power abnormal signal.

7. The power supply apparatus according to claim 6 , wherein after the power abnormal signal stops being transmitted, the system terminal changes the power on/off signal and make the supplied power generator restarts the voltage converting operation according to the power on/off signal.

8. The power supply apparatus according to claim 1 , wherein the supplied power generator comprises:

a power factor adjusting circuit coupled to the power switch, receiving and performing the voltage converting operation according to the first power or the second power to generate an output power;

a capacitor coupled to the power factor adjusting circuit, saving electric energy according to the output power; and

an output stage circuit coupled to the power factor adjusting circuit, generating the supplied power according to the output power.

9. The power supply apparatus according to claim 8 , wherein the power factor adjusting circuit is a boost voltage converter.

10. A power supplying method comprising:

providing a power switch to receive a first power and a second power respectively through a first switch and a second switch;

providing a supplied power generator to perform a voltage converting operation to the first power and the second power to generate a supplied power; and

providing the first switch to be turned on and the second switch to be cut off, and providing the supplied power generator to perform the voltage converting operation to the first power;

when the first power is judged as being cut off, during a first time period, making the first switch being cut off and making the supplied power generator stop the voltage converting operation; and

during a second time period after the first time period, making the second switch being turned on, and after the second switch is turned on, providing the supplied power generator restarts the voltage converting operation to generate the supplied power.

11. The power supplying method according to claim 10 , wherein the steps of making the first switch being cut off and making the supplied power generator stop the voltage converting operation during the first time period when the first power is being cut off comprise:

providing the supplied power generator to transmit a power abnormal signal when the first power is cut off; and

providing the supplied power generator to stop the voltage converting operation according to the power abnormal signal.

12. The power supplying method according to claim 11 , wherein the steps of providing the supplied power generator to stop the voltage converting operation according to the power abnormal signal comprise:

making the power abnormal signal being transmitted to a system terminal;

providing the system terminal to transmit a power on/off signal to the supplied power generator according to the power abnormal signal; and

providing the supplied power generator to stop the voltage converting operation according to the power on/off signal.

13. The power supplying method according to claim 12 , wherein the steps of making the second switch being turned on and providing the supplied power generator to restart the voltage converting operation to generate the supplied power after the second switch is turned on comprise:

providing the supplied power generator to stop transmitting the power abnormal signal when the second switch is turned on and receives the second power; and

proving the supplied power generator to restart the voltage converting operation after stopping transmitting the power abnormal signal.

14. The power supplying method according to claim 13 , wherein the steps of providing the supplied power generator to restart the voltage converting operation after stopping transmitting the power abnormal signal comprise:

providing the system terminal to change the power on/off signal after the power abnormal signal is stopped being transmitted and providing the supplied power generator to restart the voltage converting operation according to the power on/off signal.

15. The power supplying method according to claim 10 , wherein the voltage converting operation is a boost voltage converting operation.