Strange transistor driver circuit

In article , Philip Pemberton wrote: [....]

I've always known that circuit as a "White Darlington". I suspect that more than one person invented it.

I submit for your consideration, the "Smith Darlington"

! --------------+ !/e ! -----! PNP !/e !\\ ---! ! !/ !\\ PNP ------! ! NPN !\\e ! ------+ !

I invented this many years ago when I needed a PNP with a huge HFE.

In article , Larry Brasfield wrote: [....]

With IRF ones, they can withstand the same power but less energy. Look at the IRFPE40's datasheet. The Avalanche Current is 5.4A just like the normal drain current. By using the MOSFET to hold the voltage down a bit, you can spread out the energy from the inductive spike over more time so the temperature rise is less.

"Ken Smith" a écrit dans le message de news:d7poco$2b6$ snipped-for-privacy@blue.rahul.net...

vice

pair

Then I invent this one :

.-----------+-----+----- | | | |< |< | ----| .---| | |\\ | |\\ | | | | | | |/ | |/ '---| '---| |> |>

| | '-----------+-----

which has an even more huge HFE, uses an NPN as the power element and allow a lower VCEsat (NPN power element).

It is very pompously named a smartlington.

"Jim Thompson" a écrit dans le message de news: snipped-for-privacy@4ax.com...

allow

Certainly lower than for the 3 transitors PNP version.

For example, from the moto 3055/2955 datasheet, VBEsat @ 7A is 1.3V for the NPN vs 1.6V for the PNP.

Allow, say 150/200mV VCEsat for the driver and you have 1.5V vs 1.8V.

The "input stages" will work nicely at 1.5V and won't contribute anything to VCEsat.

This obviously don't hold if you need a power NPN. Just revert to the 3 transistors circuit.

"Jim Thompson" a écrit dans le message de news: snipped-for-privacy@4ax.com...

allow

I knew you were so nice.

"Jim Thompson" a écrit dans le message de news: snipped-for-privacy@4ax.com...

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Now we too are sure you understand this basic stuff. Well, I think.