Flexible Controller for Flyback Converters Reduces Parts Count
STMicroelectronics announced a flexible controller for high-performance flyback power converters, which can operate in fixed-frequency (FF) or quasi-resonant (QR) mode. The chip integrates protection capabilities commonly implemented with external components, and is useful for applications such as AC/DC adapters/chargers, monitors, DVD players, and set-top boxes. During light load, the chip enters a controlled burst state at low frequency with constant peak current, to minimize total power requirements and comply with worldwide energy-saving recommendations. The controller’s quiescent current (less than 3mA) and on-board non-dissipative start-up circuit further improve its efficiency. The model L6566A is designed for converters supplied through a front-end pwer factor corrector circuit, while the L6566B includes an oscillator frequency modulation input to reduce EMI. On-chip input/output protection features include over-voltage, cycle-by-cycle over-current and over-temperature protection, brownout protection, and inductor saturation detection (hi-cap mode OCP). An adaptive under voltage lock out (UVLO) circuit prevents the possibility of intermittent operation which can occur under no-load conditions due to the IC’s own supply voltage fluctuations caused by transformer parasitics. The L6566 chips are available in an SO-16 package costing $0.50 in quantities of 2,500 pieces.
781-861 2650, www.st.com