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A Schottky diode has a low forward voltage (~0.3–0.5 V) and very fast recovery, so it wastes less power and switches cleanly — ideal for rectifiers, buck-converter catch diodes, and reverse-polarity protection. Selecting one means checking three things: it can block the peak reverse voltage, carry the forward current, and stay cool.
| Requirement | Rule |
|---|---|
| Reverse voltage rating | ≥ kV × peak reverse voltage (kV = 1.5–2) |
| Forward current rating | ≥ kI × average current (kI = 2 or more) |
| Power dissipation | P = VF × Iavg |
| Junction temperature | TJ = TA + P × θJA |
Schottky diodes have higher reverse leakage than silicon, which rises fast with temperature — so avoid running them near their voltage or thermal limits, where leakage can cause thermal runaway.
A diode made with a metal-semiconductor junction. It has a low forward voltage (~0.3–0.5 V) and almost no reverse-recovery time, making it efficient and fast for rectification and switching.
Lower forward voltage means less power lost as heat and higher efficiency, and its fast recovery reduces switching loss and noise — important in low-voltage and high-frequency circuits.
Take the highest reverse voltage the diode will see and multiply by a margin of 1.5–2 to allow for ringing and transients. Never run a Schottky near its reverse-voltage limit.
Rate it at least 2× the average forward current, and check the peak/repetitive current too. Extra margin keeps the forward voltage and temperature low.
Approximately VF×Iavg for the forward loss. At high temperature and reverse voltage, add the reverse-leakage loss (VR×Ileak), which can matter for Schottkys.
Schottky diodes leak more current when reverse-biased than silicon, and this leakage rises quickly with temperature. Near the limits it can cause thermal runaway, so keep margin.
At high current, even 0.4 V of forward drop wastes a lot of power. A synchronous rectifier (a MOSFET replacing the diode) has a much lower drop and higher efficiency.
Around 0.3–0.5 V at rated current, versus ~0.7 V for silicon. It varies with current and temperature, so use the datasheet value at your operating point.
Traditional silicon Schottkys top out around 100 V. For higher voltage, silicon-carbide (SiC) Schottkys reach 600–1200 V with the same fast, low-loss behaviour.
At a few amps they often do — check the junction temperature here. If it exceeds a safe value (leave margin below the rating), add heat-sinking or a larger package.
The catch (freewheeling) diode conducts a large fraction of the cycle, so its low forward drop directly improves converter efficiency, and its fast recovery reduces switching loss.
Keep the junction 20–40 °C below the datasheet maximum for reliability, and remember that reverse leakage grows with temperature, so cooler is safer.
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