The burst-mode control is one of the most effective methods to improve the efficiency of a converter at the light load condition, but it inevitably reduces the voltage conversion ratio of the converter. In this letter, we propose a slam control for improving light load efficiency of the boost converter while maintaining its voltage conversion ratio. The proposed control method applies the full duty–ratio to the switch during predetermined time, which significantly increases the light load efficiency and sufficiently boosts the output voltage. In addition, the quasi-resonant operation enables zero voltage switching at the switch; thus, reducing further switching loss. This slam control can be easily implemented by adopting “OR gate” to synthesize the slam carrier and switching carrier. The feasibility and effectiveness of the proposed control were verified by the experimental results from a 20-W prototype. The power conversion efficiency was increased by more than 20% at the light load condition.