I isolated led three-stage and four-stage switch dimming power supply, compact design II 3-stage or 4-stage switch dimming, 3-stage dimming brightness 100% - 40% - 8% 4-stage dimming brightness 100% - 55% - 25% - 10% III output overload protection V output short circuit protection VI over temperature protection function VII suitable for 22W 20W 15W led downlight ceiling lamp surface plate lamp wall lamp