The STK730C covers the 2 A and higher current regions, regions that are difficult to handle with three terminal step-down regulators. As compared with earlier chopper regulator products that used bipolar transistors, the efficiency of the STK730C has been further improved by the adoption of MOSFET and SBD technologies, and use of the STK730C enables further miniaturization and increased performance in the end product since it corresponds to the adoption of a dedicated switching controller IC. Furthermore, due to the development of a unique MOS drive circuit, the STK730C can be used with a single power supply input. The STK730C can prove useful when standardizing and rationalizing power supply circuit design, since it can handle a wide range of power supply circuits in a number of applications, either as the secondary side regulator in a switching power supply or as the output regulator following AC transformer rectification.