Abstract: A technique for providing control for an electronic ballast by responding to the current in the common bus (DC power rail) betweeen a boost circuit such as a power factor circuit (PFC) and an output (such as a high frequency (HF) inverter) circuit, and adjusting, changing or shutting down either the power factor control circuit or the inverter circuit when the power going into the inverter circuit is above a threshold. Power going into the inverter circuit may be measured by a resistor, and temperature compensation may be provided. Excess power indicative of a spark is detected in such a way that normal starting of a lamp load connected to the ballast occurs without triggering the change/shutdown but an external arc will trigger the change/shutdown. For example, the output circuit may be shut down and the external arc curtailed within 200 msecs.

Abstract: A technique for providing control for an electronic ballast by responding to the current in the common bus (DC power rail) between a boost circuit such as a power factor circuit (PFC) and an output (such as a high frequency (HF) inverter) circuit, and adjusting, changing or shutting down either the power factor control circuit or the inverter circuit when the power going into the inverter circuit is above a threshold. Power going into the inverter circuit may be measured by a resistor, and temperature compensation may be provided. Excess power indicative of a spark is detected in such a way that normal starting of a lamp load connected to the ballast occurs without triggering the change/shutdown but an external arc will trigger the change/shutdown. For example, the output circuit may be shut down and the external arc curtailed within 200 msecs.

Abstract: A technique for providing control for an electronic ballast by responding to the current in the common bus (DC power rail) between a boost circuit such as a power factor circuit (PFC) and an output (such as a high frequency (HF) inverter) circuit, and adjusting, changing or shutting down either the power factor control circuit or the inverter circuit when the power going into the inverter circuit is above a threshold. Power going into the inverter circuit may be measured by a resistor, and temperature compensation may be provided. Excess power indicative of a spark is detected in such a way that normal starting of a lamp load connected to the ballast occurs without triggering the change/shutdown but an external arc will trigger the change/shutdown. For example, the output circuit may be shut down and the external arc curtailed within 200 msecs.