Answer 3—A boost regulator is used when the output voltage is higher than the input voltage.

 When the switch closes, the coil is charged with energy (current) while the diode blocks current from the output capacitor. When the switch opens, the coil current continues to flow through the diode, charging the capacitor. If the coil current reaches zero, the diode blocks reverse current through the coil.

Contributor: David Tweed