Patent ID: 7224086

Claim:
A power adapter comprising: an input configured to receive input power; a switch coupled to the input and configured to selectively couple the input to one of a low-voltage output and a high-voltage output, the switch being in one of a low-voltage position and a high-voltage position, respectively; a selector circuit coupled to the input and to the switch and configured to provide a control signal to the switch such that the switch will be in the low-voltage position if the input receives input power having a DC voltage lower than a threshold voltage and will be in the high-voltage position if the input power has an AC voltage higher than the threshold voltage; and a low-voltage cutout circuit configured to inhibit electrical current from flowing through the switch if the voltage input power is below a low-voltage cutout threshold, wherein the value of the low-voltage cutout threshold is determined by a peak inverse voltage of a zener diode within the low-voltage cutout circuit.