Schottky diode: when should you choose one and why?

Choosing a Schottky diode: start with the application, not the label

A Schottky diode can be useful when low forward voltage or fast switching matters. That does not make every Schottky diode suitable. Reverse voltage, current, temperature, leakage, switching behaviour, package and thermal design belong in the same selection.

Check these seven points

1. Function. Is it used for rectification, freewheeling, reverse-polarity protection, blocking or a switching converter? Loads and fault conditions differ.
2. Reverse voltage. Do not select from nominal supply voltage alone. Include ripple, transients and the margin required by the reference design or datasheet.
3. Current and surge. Compare average current, peak current and surge rating under the stated temperature and mounting conditions.
4. Forward voltage. Read VF at the actual current and temperature. A fixed value such as 0.3 V is not a product specification.
5. Leakage and temperature. Check IR at the expected reverse voltage and temperature. Leakage can rise sharply at higher temperature.
6. Switching behaviour. Check recovery behaviour and capacitance at the actual frequency and topology. The word Schottky does not replace the converter IC's design calculations.
7. Package and thermal design. Verify footprint, polarity, soldering method, thermal resistance, PCB area and maximum junction temperature.

Why the old examples are not a through-hole-versus-SMD comparison

• B2100-13-F is a 2 A/100 V Schottky in an SMB package according to the manufacturer. It is not a DO-41 through-hole part or a direct breadboard choice.
• PDS3100-13 is a 3 A/100 V Schottky in PowerDI-5, not SMA/DO-214AB.

Use either part only when its complete datasheet, footprint and thermal conditions suit the design. For a wired prototype, explicitly filter for through-hole parts and then re-check voltage, current, VF, leakage and temperature.

Safe search route

1. Define function, maximum reverse voltage, average/peak current, frequency and temperature.
2. Choose mounting style and package.
3. Compare datasheet values at your operating conditions.
4. Then search the Schottky results and verify the manufacturer part number, package and specifications before ordering.