Maxim > App Notes > Power-supply circuits Keywords: DC to DC, buck, boost, flyback, inverter, PWM, quick-PWM, voltage mode, current mode skip, synchronous rectifier Nov 29, 2001APPLICATION NOTE 2031DC-DC Converter TutorialAbstract: Switching power supplies offer higher efficiency than traditional linear power supplies. They can step-up, step-down,and invert. Some designs can isolate output voltage from the input. This article outlines the different types of switching regulatorsused in DC-DC conversion. It also reviews and compares the various control techniques for these converters.IntroductionThe power switch was the key to practical switching regulators. Prior to the invention of the Vertical Metal Oxide Semiconductor(VMOS) power switch, switching supplies were generally not practical.The inductor's main function is to limit the current slew rate through the power switch. This action limits the otherwise high-peakcurrent that would be limited by the switch resistance alone. The key advantage for using an inductor in switching regulators is thatan inductor stores energy. This energy can be expressed in Joules as a function of the current by:E = ½ × L × I²A linear regulator uses a resistive voltage drop to regulate the voltage, losing power (voltage drop times the current) in the form ofheat. A switching regulator's inductor does have a voltage drop and an associated current but the current is 90 degrees out ofphase with the voltage. Because of this, the ...