The SY21195I high-efficiency 500kHz synchronous step-down DC/DC regulator operates over a wide input voltage range of 4.5V to 18V, and can deliver an output current up to 5A. It integrates a main switch and a synchronous switch with very low RDS(ON) to minimize conduction loss. The 500kHz pseudoconstant switching frequency enables using small external inductor and capacitor values. The SY21195I uses constant-on-time and ripplebased control to achieve high efficiency at light loads and fast transient response for applications with high step-down ratios. It also provides cycleby-cycle current limiting and overtemperature protection.The SY21195I is available in a compact TSOT23-6 package.