AC/DC converting circuit

1. An AC/DC converting circuit, comprising:

an AC/DC converting unit for converting an AC voltage into a DC voltage; and

an AC/DC power conversion controller coupled to the AC/DC converting unit, detecting the AC voltage or a rectified AC voltage, and then disabling the AC voltage detection or the rectified AC voltage detection when detecting that the AC voltage or the rectified AC voltage does not rise up to a start-up voltage after a power source voltage of the AC/DC power conversion controller rises up to a released voltage level of a voltage lockout,

wherein after the power source voltage of the AC/DC power conversion controller rises up to the released voltage level of the voltage lockout and when the AC/DC power conversion controller detects that the AC voltage or the rectified AC voltage rises up to the start-up voltage and the AC voltage or the rectified AC voltage is continuously greater than the start-up voltage for a predetermined period of time, the AC/DC power conversion controller enables the AC/DC converting unit to convert the AC voltage into the DC voltage,

wherein an output terminal of the AC/DC converting unit is further coupled to a power source terminal of the AC/DC power conversion controller, and the AC/DC converting circuit further comprises:

a first rectifying unit coupled between the AC voltage and the power source terminal of the AC/DC power conversion controller and rectifying the AC voltage to generate the rectified AC voltage and to provide a DC power source to the power source terminal of the AC/DC power conversion controller,

wherein the AC/DC power conversion controller comprises:

a voltage detecting unit for detecting the AC voltage or the rectified AC voltage; and

a control unit coupled to the voltage detecting unit and the AC/DC converting unit to determine whether the AC voltage or the rectified AC voltage detected by the voltage detecting unit is greater than or equivalent to the start-up voltage, and shutting down the voltage detecting unit when the AC voltage or the rectified AC voltage is smaller than the start-up voltage, and enabling the AC/DC converting unit to convert the AC voltage into the DC voltage when the AC voltage or the rectified AC voltage is continuously greater than or equivalent to the start-up voltage for a predetermined period of time.

2. The AC/DC converting circuit as claimed in claim 1 , further comprising:

a capacitor coupled between the power source terminal of the AC/DC power conversion controller and a ground.

3. The AC/DC converting circuit as claimed in claim 1 , wherein the first rectifying unit comprises:

a rectifying diode for rectifying the AC voltage to generate the rectified AC voltage; and

a resistor connected in series with the rectifying diode between the AC voltage and the power source terminal of the AC/DC power conversion controller.

4. The AC/DC converting circuit as claimed in claim 1 , further comprising:

a voltage dividing unit coupled between the AC voltage and a ground or coupled between the rectified AC voltage and the ground, dividing the AC voltage or the rectified AC voltage to provide a voltage dividing signal to the AC/DC power conversion controller.

5. The AC/DC converting circuit as claimed in claim 4 , wherein the voltage dividing unit comprises:

a first voltage dividing resistor; and

a second voltage dividing resistor coupled in series with the first voltage dividing resistor between the AC voltage and the ground or between the rectified AC voltage and the ground, wherein a common contact of the first voltage dividing resistor and the second voltage dividing resistor is coupled to the AC/DC power conversion controller.