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Practically speaking, when is it better to use a BJT vs a FET for swtiching (not as a linear amp)?

Given that FETs have both N-channel and P-channel forms, and BJTs come in NPN or PNP, it seems that you could use either in most cases with only minor circuitry differences.

Question:

  • When would you use one versus the other?
  • Are there applications where one is absolutely necessary such that the other will not work?

Again, note this question pertains only about switching loads (including PWM), but not for use as an RF amplifier.

KJ7LNW
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  • Depletion-mode FET isn't the FET equivalent to PNP, that would be p-channel FET. – pipe Mar 16 '23 at 20:57
  • @pipe, updated question, thanks! – KJ7LNW Mar 16 '23 at 21:03
  • See https://electronics.stackexchange.com/questions/13079/when-is-a-mosfet-more-appropriate-as-a-switch-than-a-bjt – Lars Hankeln Mar 16 '23 at 21:18
  • So far as I know, there are no NFETs or PFETs that were used in the horizontal flyback of CRT TVs. I never saw one, even when FETs were being used most everywhere else. And there are domains of switching use where one or the other is to be preferred. It turns on details (wasted power dissipation being one of them, since neither approach covers the entire range of situations as a panacea.) But I think your question is really too broad. I know I don't have a comprehensive view and that it would take serious time to acquire one and then write about it. But yes, there are cases for each. – periblepsis Mar 16 '23 at 21:20
  • It's an interesting thought, but being so broad it's not really answerable beyond "well it depends" – LordTeddy Mar 16 '23 at 23:00
  • @Lars Hankeln OP asked about a "FET". The answer you linked to asked about a "MOSFET". A FET can be a JFET or a MSOFET. Therefore, I consider this to be a different question. – Davide Andrea Mar 17 '23 at 13:26

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