Selecting a Schottky diode for buck converter

Designers who have worked on buck to buck converter have a challenge of selecting an appropriate diode connected at the output of the buck converter. The diode is turned ON, when the MOSFET is in OFF condition. Schottky diode is used as the output diode. The selection criteria and some of the factors associated with the diode is,

• The diode drop must be as LOW as possible. Higher drop causes more losses resulting in the reduction of the efficiency of the converter
• The current rating of the diode must be twice the current rating of the inductor used at the output of the buck converter
• The switching speed of the diode must be high. This ensures that there are less switching losses. again this improves the efficiency
• Faster the switching of the diode, lower the spikes on the output
• The capacitance of the diode must be low which ensures that switching happens at a faster rate. This helps to reduce spikes at the output
• The peak reverse voltage of the diode must be at least twice the output voltage rating of the buck converter
• There shall be a leakage from the diode during the OFF condition. Under this scenario it is important that the reverse leakage current of the diode is as small as possible