The NB639 is a fully integrated, high frequency synchronous rectified step-down switch mode converter. It offers a very compact solution to achieve 8A continuous output current over a wide input supply range with excellent load and line regulation. The NB639 operates at high efficiency over a wide output current load range. To further optimize efficiency at light load, this device? VCC supply is designed to be biased externally. Constant-On-Time (COT) control mode provides fast transient response and eases loop stabilization. Full protection features include SCP, OCP, OVP, UVP and thermal shutdown. The NB639 requires a minimum number of readily available standard external components and is available in a space-saving 3mm x 4mm 20-pin QFN package.