The Supertex SR08x is an inductorless switching regulator designed to operate directly from a rectified AC line. The operating principle is to turn on a pass transistor when the rectified AC is below the output voltage, and to turn it off when the output voltage reaches a specific level. A linear regulator supplied by VOUT provides an additional fixed 3.3V output (SR086) or 5V output (SR087). Efficiencies of around 55% may be realized for loads up to 1W in 120VAC applications, with around 50% efficiencies for loads up to 800mW in 230VAC applications.