What Is the 1N5408? 3A Rectifier Diode and Uses
October 19, 2026 4 min read
Quick answer
The 1N5408 is a rectifier power diode that carries 3 A (1000 V reverse voltage, DO-201AD). It is used in higher-current power supplies, freewheeling and reverse-polarity protection where the 1 A 1N4007 is not enough. It is slow; for speed/low loss a Schottky (1N5822) is preferred.
The 1N5408 is a rectifier power diode that carries 3 A (the 1N540x family). It is used in higher-current power supplies where the 1 A 1N4007 is not enough. For the concept, see what is a diode.
What is the 1N5408 used for?
Medium-power supply rectification, transformer outputs, high-current freewheeling and reverse-polarity protection. With 1000 V reverse voltage and 3 A it is a step above the 1N400x family.
Specifications
| Parameter | Value |
|---|---|
| Type | Rectifier diode |
| Reverse voltage (VR) | 1000 V |
| Forward current | 3 A |
| Body | DO-201AD (band = cathode) |
Limitations
- Slow (not for SMPS); for speed use a fast/Schottky diode.
- Forward drop ~1 V; for low loss use a Schottky (1N5822).
Equivalents
- 1N5404: 400 V, 3 A.
- 6A10: a 6 A rectifier.
- 1N5822: a 3 A Schottky (low loss).
Find it in our catalog
Use the 1N5408 search.
Frequently Asked Questions
What is the 1N5408?+
The 1N5408 is a rectifier power diode that carries 3 A (1000 V reverse voltage). It is used in higher-current power supplies where the 1 A 1N4007 is not enough.
What voltage/current is the 1N5408?+
Its reverse voltage is 1000 V and its average forward current is 3 A. It is in a DO-201AD body; the banded side is the cathode.
Can the 1N5408 be used in an SMPS?+
Being slow it is not suitable for a high-frequency SMPS; if you need speed/low loss, use a Schottky (1N5822) or a fast diode.
What is an equivalent to the 1N5408?+
The 1N5404 (400 V) from the same family; the more powerful 6A10; the 3 A Schottky 1N5822 for low loss.