Diodes are semiconductor devices that can pass current in only one direction. Current is allowed to flow from the anode pin to the cathode but not in the reverse direction. This characteristic of the diode makes it a widely used choice in AC-DC rectifier circuits. Diodes are also used in logic circuits, level-shift circuits, AM detection circuits and also in snubbers and protection circuits. The Peak Reverse Voltage of a diode determines maximum voltage a diode continues to block current flow in the reverse direction. A voltage above this value causes the diode to breakdown and start conducting current in the reverse direction. The Forward current on the diode is the maximum safe current the diode can conduct in forward direction. For a Diode to start conducting current in its forward direction, The voltage source must have a voltage above the forward voltage drop of the diode else there will be no current conduction. For Switching Power Supply applications, always use diodes with very low reverse recovery time to reduce switching loses.