The STK740-470 is a separate-excitation step-down chopper regulator hybrid IC for the secondstage circuit. This IC incorporates in the package all the necessary circuits for a chopper regulator including power switch, error amplifier, soft start, shutdown type output short protection, low-voltage malfunction prevention, on/off, and snubber circuits. Therefore, external components required are input and output capacitors and a choke coil only and this allows this IC to be used to construct a large-current (5A) chopper regulator as if a 3-pin regulator were used. DC8V to 18V input voltage can be handled and up to 5A of output current is supported.