The TMI3259 is a high efficiency 520kHz, Constant-on-Time (COT) control mode, synchronous step-down DC-DC converter capable of delivering up to Peak 4.0A current with 1.2V output voltage. TMI3259 integrates main switch and synchronous switch with very low RDS(ON) to minimize the conduction loss. Low output voltage ripple and small external inductor and capacitor size are achieved with 520kHz switching frequency. It adopts the COT architecture to achieve fast transient responses for high voltage step down applications. The TMI3259 requires a minimum number of readily available standard external components and is available in a 6-pin SOT563 ROHS compliant package.