The MP9159A is a monolithic step-down, switch-mode converter with built-in power MOSFETs. It achieves a 1 A continuous output current from a 2.5 V to 6 V input voltage range with excellent load and line regulation. The output voltage can be regulated as low as 0.6 V. The constant-on-time (COT) control scheme provides fast transient response and eases loop stabilization. Fault condition protection includes cycle-by-cycle current limiting and thermal shutdown. The MP9159A is available in a small TSOT23-8 package and requires a minimum number of readily available, standard, external components. The MP9159A is ideal for a wide range of applications including high-performance DSPs, FPGAs, PDAs, and portable instruments.