The MP2131 is a monolithic step-down, switch- mode converter with built-in internal power MOSFETs. It achieves a 4 A continuous output current from a 2.7 V to 5.5 V input voltage with excellent load and line regulation. The MP2131 is ideal for powering portable equipment that run from a single cell lithium-ion (Li+) battery. The output voltage is regulated as low as 0.6 V. The constant-on-time (COT) control scheme provides fast transient response, high light-load efficiency, and eases loop stabilization. Fault condition protection includes cycle?y?ycle current limit and thermal shutdown. The MP2131 requires a minimum number of readily available, standard, external components and is available in an ultra-small QFN-12 (2mm x 2mm) package. The MP2131 is ideal for a wide range of applications including portable instruments, small handheld and battery?owered devices, PDAs, and DVD drives.