Abstract: A totem pole power factor correction circuit includes a detection module and a control unit. The detection module includes a first detection resistor and a first detection circuit. After a voltage difference between the two terminals of the first detection resistor is detected by the first detection circuit, an output voltage is generated. The control unit determines the operating state of the totem pole power factor correction circuit according to the output voltage. If the totem pole power factor correction circuit is in the normal working state, and the totem pole power factor correction circuit is in a steady state or the output power (or the input voltage) is increased or decreased, the control unit controls the on/off states of the corresponding switches in the totem pole power factor correction circuit according to the output voltage.

Abstract: An isolated DC-DC converter including n conversion circuit units is provided. In each conversion circuit unit, a first connection node is formed between two switching components of a first primary bridge arm, and a second connection node is formed between two electronic components of a second primary bridge arm. A third connection node is formed between two switching components of a first secondary bridge arm, and a fourth connection node is formed between two switching components of a second secondary bridge arm. A first coupling inductor and A first capacitor are serially coupled between the first and third connection nodes. A second coupling inductor and a second capacitor are serially coupled between the second and fourth connection nodes. In the n conversion circuit units, the primary circuit units are electrically connected in series or in parallel, and the secondary circuit units are electrically connected in parallel or in series correspondingly.

Abstract: A totem pole power factor correction circuit is provided. The detection module in the totem pole power factor correction circuit includes a detection resistor and a detection circuit. If the output voltage outputted by the detection circuit is greater than or equal to an upper limit voltage threshold or lower than or equal to a lower limit voltage threshold, at least a third switch and a fourth switch are turned off under control of the control unit. Consequently, the totem pole power factor correction circuit can be protected. Under this circumstance, the protecting measure can be taken immediately. Consequently, the possibility of causing damage of the totem pole power factor correction circuit will be minimized. In other words, the performance of the totem pole power factor correction circuit is enhanced.