A circuit is provided. The circuit includes a control circuit, a voltage sensor coupled to the control circuit, and an indicator signal coupled to the control circuit. The control circuit, responsive to the voltage sensor, is configured to detect a first classification voltage within a classification voltage range defined by a lower classification voltage limit and upper classification voltage limit, detect, after detecting the first classification voltage, an indexing voltage outside of the classification voltage range, and detect, after detecting the indexing voltage, a second classification voltage within the classification voltage range. The control circuit is further configured to set the indicator signal to a first predetermined state indicating a power type based on the detected first classification voltage, indexing voltage and second classification voltage.