Flyback-Converter Controllers Support Two Operating Modes

Promoting flexibility and cost reductions, the L6566 flyback-converter controllers operate in either fixed-frequency or quasi-resonant mode. Operating mode is selectable via connection of a single pin. Under very light-load conditions, in both operating modes, the chip enters a controlled burst-mode state at low frequency with constant peak current to minimize total power requirements and to comply with worldwide energy saving requirements. Quiescent current is less than 3 mA. Available in two versions, L6566A and L6566B, the L6566A suits converters employing a front-end PFC circuit. It provides an interface to the PFC to turn off the regulator under light or no-load conditions and during all fault conditions. The L6566B targets applications with no front-end PFC and it includes an oscillator frequency modulation input to reduce EMI. Available in an SO-16 package, price for the L6566 is $0.50 each/2,500. STMICROELECTRONICS, Lexington, MA. (888) 787-3550.