A voltage conversion apparatus includes a power supply circuit with a first switch, a voltage conversion circuit, and a protective circuit with a detection circuit. The first switch transmits a power to generate an input voltage. The voltage conversion circuit generates a first voltage. A second switch of the voltage conversion circuit receives the input voltage. A third switch of the voltage conversion circuit is coupled between the second switch and a ground terminal. The detection circuit generates a first control signal based on the first voltage, a second voltage that corresponds to the first voltage, and a reference voltage. When a voltage value of an error signal is less than the reference voltage, the detection circuit outputs the first control signal to turn off the first switch. The voltage value of the error signal corresponds to a voltage difference between the first voltage and the second voltage.