Patent ID: 8830637

Claim:
An output overvoltage protection circuit, comprising: a first terminal configured to receive an alternating current signal through a first capacitor for conversion to a second signal; a second terminal to receive the second signal based on the alternating current signal; a second capacitor in circuit with the first terminal prior to the conversion of the alternating current signal to a direct current signal; a switch in circuit with the second capacitor and the first terminal configured to selectively electrically couple the second capacitor to the first terminal based on an overvoltage detection signal to reduce an overvoltage on the second signal; and an overvoltage detector in circuit with the second terminal and the switch and configured to determine a signal level of the second signal and, in response to determining that the signal level of the second signal is greater than a threshold, to output the overvoltage detection signal to cause the switch to electrically couple the second capacitor between the first terminal and a third terminal to reduce overvoltage at an output; further comprising a rectifier circuit in circuit with the first and second terminals, the first capacitor, and the switch and configured to generate the second signal, wherein the switch selectively couples the second capacitor between the first terminal and a reference; and a second switch configured to selectively couple a third capacitor between the third terminal and the reference based on the overvoltage detection signal when an electrical signal level on the third terminal is less than a second threshold.