Voltage switching circuit and power adapter having regulated range of output voltage

A power adapter, comprising:

• a power factor correction circuit comprising a bus capacitor;
• a first converter comprising an input electrically connected to the bus capacitor and a first output for outputting a first voltage;
• a second converter comprising an input electrically connected to the bus capacitor and a second output for outputting a second voltage;
• and
• a voltage switching circuit comprising:
• a first switching circuit including a first switch and having a first terminal for receiving the first voltage;
• and
• a second switching circuit including a second switch and having a first terminal for receiving the second voltage,
• wherein a second terminal of the first switching circuit is electrically connected to a second terminal of the second switching circuit to form a switching terminal for outputting an output voltage,
• wherein when the output voltage is required to be switched from the first voltage to the second voltage, the first switching circuit is controlled to be turned off, and then the second switching circuit is controlled to be turned on such that the output voltage is switched to the second voltage, and
• wherein when a voltage at the first terminal of the second switching circuit is higher than a preset voltage, the second converter is shut down or kept off.