Publisher Summary This chapter discusses the time domain of ideal inductors and capacitors and presents ideal versions of each type of switching supply. An ideal buck converter regulator is presented that is made of an ideal voltage source, an ideal voltage controlled switch, an ideal diode, an ideal inductor, an ideal capacitor, and a load resistor. It is called a buck converter because the voltage across the inductor “bucks” or opposes the supply voltage. The output voltage of a buck converter is always less than the input voltage. The chapter also presents an ideal boost converter regulator made of an ideal voltage source, an ideal switch, an ideal diode, an ideal inductor, a capacitor, and a load resistor. It is called a boost converter because the voltage across the inductor adds to the input supply voltage to boost the voltage above the input value. The output of a boost converter is always greater than the input voltage. Boost converters require much more capacitance than a buck converter the capacitor supplies the entire load current while the switch is closed.