Schottky Diode
Diode
A diode with a very low forward voltage drop and fast switching speed, made from a metal-semiconductor junction instead of a p-n junction.
Schematic symbol
Diode
How schottky diode appears in a circuit diagram.
Types & variants
Key specs
Forward voltage
Volt (V)Voltage drop when conducting. Typically 0.15-0.45V, much lower than standard silicon diodes.
Forward current
Ampere (A)Max current it can handle continuously without overheating.
Reverse breakdown voltage
Volt (V)Max reverse voltage before breakdown occurs. Lower than standard diodes.
Reverse leakage current
µACurrent that flows when reverse-biased. Higher than standard diodes.
Switching speed
nsHow fast it transitions between states. Very fast (picoseconds to nanoseconds).
Markings
Through-hole: cathode marked with a band or line. SMD: cathode marked with a line, dot, or code. Common codes: 'SS', 'SK', 'SB', or part numbers like '1N5817'.
Standard values
Common voltage ratings: 20V, 30V, 40V, 60V. Common current ratings: 1A, 3A, 10A, 20A. Part numbers: 1N5817 (1A/20V), 1N5822 (3A/40V).
How to choose
1) Determine required forward current and reverse voltage. 2) Select with voltage rating 20% above max circuit voltage. 3) Choose current rating above max expected current. 4) Consider thermal management for high current applications.
Pinout & package
2 leads: anode (positive) and cathode (negative). Cathode is marked with a band or line. Packages: DO-41, DO-201, SMA, SMB, SMC (through-hole and SMD).
Example circuits
- Reverse polarity protection
- RF detectors and mixers
- Switch-mode power supplies (SMPS)
- Solar cell bypass diodes
- Logic level shifting
Common failures
Short-circuit (metal migration) from overvoltage/overcurrent; open-circuit from extreme overheating. Visible signs: discoloration, burn marks, or cracked package.
How to test
Set multimeter to diode mode. Forward bias: should show 0.1-0.5V. Reverse bias: should show 'OL' or very high resistance. Compare with known good diode.
Substitutes
Standard silicon diodes (higher forward voltage), MOSFETs for reverse polarity protection (lower losses). Choose Schottky with same or higher voltage/current ratings.