The 1N5408 is a heavy-duty power rectifier diode from the 1N540x family. While it functions similarly to the 1N4007, the 1N5408 is designed for much higher power applications. It can handle a continuous forward current of up to 3A and a peak reverse voltage of 1000V. This makes it the standard choice for high-power DC supplies, battery chargers, and large motor controllers where a 1A diode would overheat or fail. The physical size is slightly larger (DO-201AD package) to help dissipate the heat generated by higher current flow.
1N5408 Pinout (DO-201AD)
The 1N5408 is an axial-leaded diode with a larger body than the 1N4007. The cathode is marked with a silver or white band.
| Pin | Terminal | Description |
| 1 | Cathode | The negative terminal (marked with a band) |
| 2 | Anode | The positive terminal |
Technical Specifications – maximum
- Peak Repetitive Reverse Voltage (VRRM): 1000V
- Average Forward Rectified Current (IO): 3.0A
- Non-Repetitive Peak Forward Surge Current (IFSM): 200A
- Forward Voltage Drop (VF): 1.2V (at 3A)
- Reverse Current (IR): 5.0µA
- Operating Junction Temperature: -65°C to +150°C
Key Features & Benefits
- 3-Amp Capacity: Triple the current handling of the 1N400x series.
- Massive Surge Protection: Can handle a 200A surge for short durations.
- High Voltage Rating: 1000V capacity allows for safe use in AC mains rectification.
- Robust Construction: Large DO-201AD package provides better heat dissipation.
Common Applications
- High-Power Rectification: Used in 3A bridge rectifiers for power tools and chargers.
- Battery Chargers: Managing charging currents for lead-acid and lithium packs.
- Motor Protection: Handling large back-EMF spikes from powerful DC motors.
- Polarity Protection: High-current protection for automotive electronics.
1N5408 Equivalent & Substitutes
- 1N5400 to 1N5407 (Lower voltage versions)
- UF5408 (Ultra-fast version for switching supplies)
- 6A10 (10A version for even higher power requirements)
- SK310 (SMD version)
Related Tutorials on ElxHub
- Basics: Diodes – Basics, Types, and Working
- Selection Guide: Ultimate Diode Selection Guide
Conclusion
The 1N5408 is the go-to power diode for projects that demand high current and high voltage. Its reliability in heavy-duty rectification and protection tasks makes it a fundamental part of any power electronics design. When 1A is not enough, the 1N5408 provides the necessary overhead to keep your high-power circuits running cool and safe.
Download the Diode Datasheet pdf:
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