Design of high-power-density switching power supply with low light-load losses

Abstract Planar transformers offer advantages such as compact size, high conversion efficiency, and excellent thermal performance, making their design solutions particularly suitable for high-power-density switching power supplies. The light-load losses in switching power supplies primarily stem from switching losses. This study proposes a control circuit design method to reduce no-load and light-load losses while improving power supply efficiency. The paper elaborates on both the transformer parameter design selection and the modular circuit design strategies for minimizing no-load and light-load losses. Experimental results demonstrate the power supply achieves a peak-to-peak output voltage ripple of merely 200 mV at full load, maintains efficiency exceeding 86%, and complies with the standby power consumption requirements of the Energy Star standards.