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flippityflop

diodes with breakdown current instead of voltage breakdown

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i know this is a stupid question but i'll ask away anyways...

are there any diodes that instead would have a specified *current breakdown* rather than a voltage breakdown? i know it's stupid coz the current would have to flow first to know the amp to know when it should break, but the diode is already hindering that flow in the first place.

in an analogy of transistors, diodes are dependent on voltage, as are FETs. the BJTs are dependent on current.... so are there any diodes dependent on current too??
(though the analogy is somewhat forced, as diodes actually work on the same principles as BJTs, not FETs -- other way around -- but i'm just illustrating a point).

the best compromise i could think of was an NPN or PNP semiconductor, where the gate is connected to a V+ or common ground, respectively. then a small current flowing through base-emitter would cause the base to "breakdown" at the desired current. courtesy of (typically) smaller current (proportional to reciprocal of gain) flowing deep inside the base-emitter junction. this will allow an avalanche through emitter-collector. but chances are, it's already implemented as a BJT transistor... (still reading wikis for avalanche transistors, actually).

anyways, i still prefer it to be in diode implementation, so if it exist, please hit "reply"

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It doesn't work like that because as you say, the current needs to flow.

You can get constant current diodes which pass a fixed current, regardless of the voltage - it's just a J-FET with the gate connected to the source.

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Current specifications aren't used much for diodes unless they're exceeded. Jfets have the input connected to the channel. The substate is shorted to the source.

I'll edit this post. Only MOS field effect transistors have their substrate shorted to the source most often. Jfets are biased with a reverse bias gate to drain voltage, or else it conducts Idss at 0VGS. An interesting fact is that because of the reverse bias gate to drain voltage. the source current is a little less.

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JFETs are symmetrical - the source and drain connections are interchangeable.
http://en.wikipedia.org/wiki/JFET



I was talking about a constant current diode which is just a JFET with the gate connected to the source, often via a resistor.
http://docs-europe.electrocomponents.com/webdocs/0027/0900766b80027bdf.pdf

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