CPC H02J 3/46 (2013.01) [H02H 7/22 (2013.01); H02M 3/33576 (2013.01)] | 16 Claims |
1. A power supply apparatus, comprising:
a transformer comprising a first primary winding configured for connection to a first power source and a second primary winding configured for connection to a second power source, and a secondary winding configured for delivering power therefrom as an output of the power supply apparatus; and
a controller configured to receive voltage inputs from the first power source and the second power source, and in response to the received voltage inputs control supply from the first power source to the first primary winding and from the second power source to the second primary winding, such that when the first power source and second power source are available the controller operates to allow power to be supplied to the first primary winding from the first power source and operates to shut off supply of power to the second primary winding from the second power source;
wherein the controller comprises:
a voltage detection circuit configured to compare a voltage of the first power source to a value produced by a voltage reference circuit to determine for the controller that the first power source is available; and
an under voltage lock circuit configured to detect an under-threshold voltage and prevent the controller from allowing power to be supplied to the first primary winding from the first power source.
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