WHY? 1N400X

[innkeeper]

OK, I've seen this question pondered before but never really seen a good explanation.

The garden variety 1N400x comes voltages from 50v to 1000V
but there all the exact same spec otherwise and same cost. ... so why bother with anything other then a 1n4007?
whats the point in bothering having multiple voltages?

Vishay spec sheet example:
http://www.vishay.com/docs/88503/1n4001.pdf

[NiHaoMike]

I remember reading that if you make a diode able to withstand a higher reverse voltage, it comes at the cost of a slightly higher forward voltage.

[coppice]

but there all the exact same spec otherwise and same cost

Try ordering millions, and see if the cost is still the same when you start negotiating a serious price. 

[A Hellene]

Higher blocking voltage->wider drift region->lower doping concentration->higher resistance->higher Vf at a given (high) current.
So maybe they all have 0.7V Vf at 0.1A, but if you apply a 10A pulse, you will start to see the difference.

Along with higher blocking voltages lower switching speeds come also; but in such slow diodes (~2.5 micro seconds) the difference is negligible. For the fast / super fast / ultra fast (and Schottky) diodes it makes a big difference, though.

BYV26's switching speed, for example, changes dramatically; from 30ns for up to 700V parts (BYV26A..C) to 75ns for the 900 and 1100V parts (BYV26D..E).


-George

[innkeeper]

Higher blocking voltage->wider drift region->lower doping concentration->higher resistance->higher Vf at a given (high) current.
So maybe they all have 0.7V Vf at 0.1A, but if you apply a 10A pulse, you will start to see the difference.

have you actually seen that with a 1n400x series. form what i have seen and what the specs say, seems not to be the case.
in fact the specs state the same vf for a given current for all in the series.

[innkeeper]

but there all the exact same spec otherwise and same cost

Try ordering millions, and see if the cost is still the same when you start negotiating a serious price. 

same prices

Mouser Part #:
863-1N4001G
Manufacturer Part #:
1N4001G
Manufacturer:
ON Semiconductor
Description:
Rectifiers 50V 1A Standard
1N4001G 1: $0.18
1N4001G 100,000: $0.017

Mouser Part #:
863-1N4007G
Manufacturer Part #:
1N4007G
Manufacturer:
ON Semiconductor
Description:
Rectifiers 1000V 1A Standard
1N4007G 1: $0.18
1N4007G 100,000: $0.017

[innkeeper]

have you actually seen that with a 1n400x series. form what i have seen and what the specs say, seems not to be the case.
in fact the specs state the same vf for a given current for all in the series.

It's common for manufacturers to rate Vf at worst case, so they can rate Vf at 4007 for all 400x devices.
It's also common for a manufacture to use the same die for 4001~4004, and a lower doping concentration die for 4005~4007.
Therefore, while the manufacture doesn't guarantee your 4001 to block 400V, it's likely it can.

that sounds a lot more likely.

[innkeeper]

I remember reading that if you make a diode able to withstand a higher reverse voltage, it comes at the cost of a slightly higher forward voltage.

me too, but seems not with these. its like there all the same part or soming

[Someone]

have you actually seen that with a 1n400x series. form what i have seen and what the specs say, seems not to be the case.
in fact the specs state the same vf for a given current for all in the series.

It's common for manufacturers to rate Vf at worst case, so they can rate Vf at 4007 for all 400x devices.
It's also common for a manufacture to use the same die for 4001~4004, and a lower doping concentration die for 4005~4007.
Therefore, while the manufacture doesn't guarantee your 4001 to block 400V, it's likely it can.

that sounds a lot more likely.

Historical probably:
https://electronics.stackexchange.com/questions/84471/what-is-the-difference-between-1n4001-and-1n4007-other-than-their-maximum-revers/84522

A part number and associated data sheet is just a specification, the actual parts delivered can change over the life of the product and come from different processes/foundries or for opamps even different designs! Tighter specifications on the forward voltages or forward resistance, reverse leakage etc are all available if you pay more for testing and get a new part number assigned. If you read the 1N400x data sheets carefully they mostly claim a "Maximum forward Voltage" which in the past could have been achieved with several different junction profiles/designs, but is now done easily with a single part.

I'd guess the biggest differentiator in the "unified" 1N400x lines would be that the maximum reverse leakage is specified at the rated DC voltage, so its a simple binning there with scope to downrate parts as demand arises. Leakages in diodes still varies quite a lot in production.