A supply voltage control circuit configured to provide a supply voltage for a control circuit of a switched power supply, the supply voltage control circuit comprises: a supply voltage generation circuit having a first capacitor (C41, C42) and a first output terminal, the first capacitor being charged to generate a supply voltage, the supply voltage being outputted from the first output terminal of the supply voltage generation circuit to the control circuit; a charge switch element, a gate of which being connected to a charge node, wherein, when the charge switch element is turned on, the charge switch element is configured to supply a current for charging the first capacitor (C41, C42); and a short-circuit detecting and switching unit, which is connected to the first output terminal of the supply voltage generation circuit, wherein, when the first capacitor (C41, C42) of the supply voltage generation circuit is shorted, the short-circuit detecting and switching unit is configured to turn off the charge switch element, so as to stop supplying the current for charging the first capacitor (C41, C42), characterized in that the short-circuit detecting and switching unit comprises a first switch element and a second switch element; wherein, a gate of the first switch element is connected to the first output terminal via a first diode unit, a drain of the first switch element is connected to the charge node via a first resistor, a gate of the second switch element is connected to the drain of the first switch element, a drain of the second switch element is connected to the gate of charge switch element, and wherein, when the first capacitor (C41, C42) of the supply voltage generation circuit is not shorted, the first switch element is conducting, the second switch element is switched off, and the charge switch element is conducting, and when the first capacitor (C41, C42) of the supply voltage generation circuit is shorted, the first switch element is switched off, the second switch element is conducting, and the charge switch element is switched off. a supply voltage generation circuit having a first capacitor (C41, C42) and a first output terminal, the first capacitor being charged to generate a supply voltage, the supply voltage being outputted from the first output terminal of the supply voltage generation circuit to the control circuit; a charge switch element, a gate of which being connected to a charge node, wherein, when the charge switch element is turned on, the charge switch element is configured to supply a current for charging the first capacitor (C41, C42); and a short-circuit detecting and switching unit, which is connected to the first output terminal of the supply voltage generation circuit, wherein, when the first capacitor (C41, C42) of the supply voltage generation circuit is shorted, the short-circuit detecting and switching unit is configured to turn off the charge switch element, so as to stop supplying the current for charging the first capacitor (C41, C42), characterized in that the short-circuit detecting and switching unit comprises a first switch element and a second switch element; wherein, a gate of the first switch element is connected to the first output terminal via a first diode unit, a drain of the first switch element is connected to the charge node via a first resistor, a gate of the second switch element is connected to the drain of the first switch element, a drain of the second switch element is connected to the gate of charge switch element, and wherein, when the first capacitor (C41, C42) of the supply voltage generation circuit is not shorted, the first switch element is conducting, the second switch element is switched off, and the charge switch element is conducting, and when the first capacitor (C41, C42) of the supply voltage generation circuit is shorted, the first switch element is switched off, the second switch element is conducting, and the charge switch element is switched off.