A High-Efficiency AC-to-DC Adaptor With a Low Standby Power Consumption

A two-stage burst mode control scheme for an AC-to-DC adaptor is proposed in this paper. An upper limit for the output voltage is set to turn off both AC/DC and DC/DC controllers at no load. The burst-mode operations of the DC/DC and the AC/DC converters are in turn enabled when reaching the lower limit of the output voltage. Load analysis at standby mode is performed. A 50-mW no-load power loss is observed on an 80 W/12 V prototype adaptor.