This paper presents a two-stage electronic ballast for metal-halide (MH) lamps. The first stage is a single-switch flyback and buck-boost integrated converter. The post stage is a half-bridge inverter driving the MH lamps with low-frequency square-wave current for avoiding acoustic resonance. The operating principle of the proposed topology is discussed. Also, constant power control is realized using the methodology employed for peak inductor current control. Finally, a laboratory prototype of a 70W electronic ballast for MH lamp operated with 200264V input voltage is implemented to verify the feasibility. The measured results illustrate that the harmonic distortion of AC input current satisfies the requirements of the IEC 61000-3-2 Class C standard.