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’s 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 QFN20 (3x4mm) package.Wide 4.5V to 28V Operating Input Range 8A Output Current Internal 30m? High-Side, 12m? Low-Side Power MOSFETs Proprietary Switching Loss Reduction Technique 1% Reference Voltage Programmable Soft Start Time Soft Shutdown Programmable Switching Frequency SCP, OCP, OVP, UVP Protection and Thermal Shutdown Output Adjustable from 0.8V to 13V Available in a QFN20 (3x4mm) Package