The MP2321 is a fully-integrated, high-efficiency, synchronous, step-down, switch-mode converter with 40? of quiescent current. The MP2321 achieves 2A of continuous output current over a wide input supply range with excellent load and line regulation and can operate with high efficiency over a wide output current load range. The MP2321 is optimized for battery-operated applications and applications requiring high light-load efficiency. With constant-on-time (COT) control, the MP2321 provides very fast transient response, easy loop design, and very tight output regulation. Full protection features include short-circuit protection (SCP), over-current protection (OCP), under-voltage protection (UVP), and thermal shutdown. The MP2321 requires a minimal number of readily available, standard, external components and is available in a space-saving QFN-14 (2mmx3mm) package.