Supertex HV9801A Switch Dimmable LED Drivers are ideally suited for switch dimmable applications using LED bulbs and fixtures. Through switch dimming, the lamp can be adjusted to four discrete brightness levels by rapid cycling of the light switch. The brightness levels are traversed in an up and down manner. Brightness resumes at the highest level when power is removed for more than a second. Supertex HV9801A Switch Dimmable LED Drivers can be powered directly from rectified AC through an internal VDD regulator rated at 450V.