1N4001 Diode subjected to 300V reverse voltage and it did not break down?

Thread Starter

Sensacell

Joined Jun 19, 2012
3,453
I am working on a teaching video about diodes...

I just connected a 1N4001 in series with a 100K resistor in reverse bias across an adjustable supply, I monitored the voltage over the resistor and diode at the same time.

I was expecting something to happen around ~ 100 V - double it's rated voltage.
But I slowly increased the voltage and got up to 300V and... nothing happened! it held off 300V!

The leakage current increased linearly at about 10uA per 100 Volts of bias.

This seems really odd, that's 6X the rated reverse voltage!!
 

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LowQCab

Joined Nov 6, 2012
4,078
Two possibilities ...........

Sometimes manufacturers will "re-label" a higher-rated-part
if their stock is low on a very common, lower-rated-part.

It's much less expensive to create a single part that will
cover the expected performance-ratings of several part-numbers.
Generally nobody cares, or even notices, if the Part will "out-perform" the claimed specs.
.
.
.
 

Pyrex

Joined Feb 16, 2022
268
Hi,
the manufacturers specify breakdown voltage at elevated temperatures. It means, the diode must withstand the given voltage and amperage at the same time. So, if forward current is close to zero, the structure is relatively cold and breakdown voltage is much higher than specified
 

crutschow

Joined Mar 14, 2008
34,470
The 1N400x series of diodes are all made with the same process and then sorted according to their breakdown voltage which determines their rating.
If a particular batch happens to produce a lot of high voltage units, then some may be labeled with the lower rating just to resupply their stock.
 

Thread Starter

Sensacell

Joined Jun 19, 2012
3,453
The 1N400x series of diodes are all made with the same process and then sorted according to their breakdown voltage which determines their rating.
If a particular batch happens to produce a lot of high voltage units, then some may be labeled with the lower rating just to resupply their stock.
This makes total sense! thank you!
 

WBahn

Joined Mar 31, 2012
30,082
I am working on a teaching video about diodes...

I just connected a 1N4001 in series with a 100K resistor in reverse bias across an adjustable supply, I monitored the voltage over the resistor and diode at the same time.

I was expecting something to happen around ~ 100 V - double it's rated voltage.
But I slowly increased the voltage and got up to 300V and... nothing happened! it held off 300V!

The leakage current increased linearly at about 10uA per 100 Volts of bias.

This seems really odd, that's 6X the rated reverse voltage!!
If the leakage current increased linearly at 10 µA / 100 V, then at 50 V it would have been right about 5 µA.

Look at the spec sheet:

1702358126935.png

If they had 5 µA at between 50 V and 100 V (at 25°V), then the highest reverse DC blocking voltage they can be rated at is 50 V -- and this one would barely meet spec.
 

MisterBill2

Joined Jan 23, 2018
18,600
The specification sheet tells you the maximum performance that the product is promised to provide. That does not mean that some devices will not provide much higher performance, but only that they will meet the specification. And so one in the package may be much better and another might be only a small amount better.
 
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