# What is Maximum Average Forward Rectified Current? (1N4001 Diode)

I am wondering if someone can explain what Maximum Average Forward Rectified Current means for a diode. I see that this is marked as 1 Amp in the datasheet for the 1N4001. I have not been able to find a clear explanation of what this means online.

This came up when I was doing stress testing on a circuit I am designing. I was driving the circuit under it's maximum conditions for long periods of time. In these tests 1.7 Amps of current passed through a 1N4001 diode for over 10 minutes. The diode did not get hot or show any signs of distress. Someone later pointed out the 1 Amp in the datasheet, but clearly this doesn't mean the maximum current that can pass through the device, or there would have been some sort of negative effect.

Can anyone explain what this attribute means for a diode, and why the circuit operated without any negative effects at the higher current?

• The fact that you didn't observe a negative effect doesn't mean there wasn't one. The reliability of the diode may be greatly reduced and it could fail tomorrow. Furthermore, you may have just gotten lucky...the next 99 diodes you try may fail catastrophically when you pass 1.1A through them. The maximum current spec doesn't mean the diodes will fail when you exceed that current, it means they won't fail if you stay below the spec. Sep 13, 2018 at 0:35
• Something must be really wrong with your measurements. Typical 1N4001 has D=2mm and L=4mm, it is a fairly small device. At 1.7 V the forward voltage is about 1.1V, so the dissipated power is nearly 2W This is huge power for a device that small, unless the legs are soldered to massive pads/wires. The device gets fairly hot, Tcase goes to 70C, I just happen to have an old sample of 1N4001 and run the test, it burns fingers. Sep 13, 2018 at 1:19
• The diode got very hot if the current was actually passing through it. Maybe you didn't notice because it cooled relatively quickly. Sep 13, 2018 at 1:19