Patent ID: 8094471

Claim:
A power supply, comprising: a rectifier circuit having a rectifier mode and a voltage doubler mode; an AC switch coupled to the rectifier circuit for switching the rectifier circuit into the rectifier mode when a higher AC line voltage is supplied and a voltage doubler mode when a lower AC line voltage is supplied; and a control circuit connected to the AC switch that detects the higher or lower AC line voltages and operable for latching the rectifier circuit in the rectifier mode when the higher AC line voltage is detected and in the voltage doubler mode when the lower AC line voltage is detected and maintaining a latched configuration in either the rectifier or voltage doubler mode during voltage transients and in the rectifier mode during start-up transients, wherein said control circuit comprises a low voltage detect and latch circuit configured to sense the lower AC supply voltage, and a latch inhibit circuit that detects the AC supply voltage and outputs an inhibit signal in response to the detection of a lower input voltage, and a high voltage detect and latch circuit connected between the low voltage detect and latch circuit and the AC switch and in the presence of the lower voltage and receipt of the latch signal, configure the AC switch to switch the rectifier circuit into the voltage doubler mode and remain in a latched condition, and in the absence of the inhibit signal and in the presence of the higher voltage configure the AC switch to switch the rectifier circuit into a rectifier mode and remain in the latched condition, wherein the low voltage detect and latch circuit includes a time delay circuit responsive to voltage changes and allow a voltage to reach a peak value before detecting an AC supply voltage and generating an inhibit signal.