Abstract—This paper presents a three-in-one converter for regular and emergency lighting applications. The converter can function as regular ballast, emergency ballast, and battery charger/discharger, achieving regular and emergency lighting features. The three-in-one converter used in the ballast is an integration of a bidirectional flyback converter and two half-bridge series-resonant parallel-loaded inverters. The derivation and operating principle of the proposed converter are first presented, and an application to regular and emergency lighting is then developed. With the proposed converter and a single-chip microcontroller EM78P458, a low cost multifeature electronic ballast can be readily implemented and installed. Hardware measurements have verified its feasibility and the desired features.