An electronic circuit for use with a lamp controller includes a driver component and a voltage interface circuit powered by the driver component. The interface component delivers a low voltage power signal at a defined operating range via output lines to a downstream controller. A protection circuit is coupled with the voltage interface circuit. The protection circuit in one embodiment has an under-voltage switch disposed in one of the output lines and configured to open at a voltage less than the defined voltage range, and a blocking device disposed in the other output line and configured to block reverse power flow at a voltage above the defined voltage range. In another embodiment, the protection circuit has a first blocking device disposed in either one of the output lines to block reverse power flow to the voltage interface circuit, a PTC device disposed in either one of the output lines, and a second blocking device disposed across the output lines to protect the control circuit from a high voltage reverse polarity condition.