Dirt cheap inverter/buffer with RDSon < 10 ohm?

How about an HCT or ACT hex something, one section driving the other five in parallel? You've basically got that in the AC14.

I like ON SEMI NL37WZ16US, at abs max Vcc, three sections in parallel, insanely fast, 12 cents, but that needs CMOS level drive, not HCT.

I drive 3 FETs, so that would be one package per FET. I would like to drive them all from a single IC, 3 pcs is too expensive.

That is a good one, similar to the other ones I found, equivalent resistance of about 17 ohms, but about 3 times to high

I have looked into analog switches, which comes down in the numbers needed, but then the manufacturer knows well that he can ask for a higher price :-(

Cheers

Klaus

Clock fanout drivers may be of interest.

Probably not much more drive or cheapness than jellybean logic gates, though.

Tim

-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website:

But an analog switch can only drive in one direction, so you'd need two per MOSFET. Expensive.

Paralleling two 'AC14 sections and driving both with a third 'AC14 section would get you two drivers per 'AC14 package.

An octal buffer part (e.g. the 'AC240) would get you three drivers. But, in this service, do you really *want* three drivers talking to each other over a common bond wire to ground?

Cheers, James Arthur

Oh dear, an octal is one gate shy. Scratch that. But you could use an octal, make two drivers with six gates, and the last driver with one external buffer e.g.,

Depends on what you're switching and how fast it needs to be.

Cheers, James Arthur

What is the part number of your medium power MOSFET?

Well, no, the double throw analog switch makes it easy:

Yes, might be an option, but still more expensive that I would like

No problem with ground, but the 74AC240 is expensive

Cheers

Klaus

Yes, a picogate could be external for the one that is needed for driving the other 2 gates

That is pretty close to be the same as the current optimum circuit I am working on :-)

Cheers

Klaus

You must be driving giant fets. The NL37WZ16 rise time, unloaded, is about 700 ps. Driving the just-right-size fet, you can switch 50 volts at 1 amp in about a nanosecond.

Of course, our products are lowish quantity, and parts cost doesn't usually matter much. I sometimes use two or even three of the tiny triples in parallel (like, 9 gates!) to drive a mosfet.

"Anything worth doing is worth overdoing."

- Meat Loaf

The USB switches are fairly cheap and just a few ohms.

Yikes. What switching speed do you want?

Although it still has the problem of coming up one short, if your signal isn't inverted.

Tim

You could at least try a permanently-enabled NC7SZ125 TinyLogic 3-state line driver (or its TI equivalent SN74LVC1G125).

The datasheet does not say much, but my experience with them so far is, that they are considerably "beefier" than other typical logic outputs. If accidentally driven against a 3.3V CPU or FPGA output pin, it would easily overdrive the CPU / FPGA pin strongly enough to land at a valid opposite logic level. The only indication that something is wrong apart from the other chip not being made to stand this for very long, was a small voltage offset from VCC (or from GND) on the offending signal, an offset small enough to be quite easily overlooked.

The datasheet specifies 32 mA output at 4.5 V supply, but that's rated output current. Peak current into a dead short is rather around 150 mA (not that the chip would be expected to survive it very long either).

Dimitrij

Nice part! I may have a use for that one.

rive the power MOSFET possible

tes to euquivalent RDSon to about 26 ohms

would be an questionable approach

dirt cheap, preferable 2-3 or more parts in a package

ive them all from a single IC, 3 pcs is too expensive.

ance of about 17 ohms, but about 3 times to high

The problem is not driving them on, but making sure that when they are off, that they stay off. Say you have a half bridge configuration and the top F ET has been on. It is turned off, and some ns later, the lowside FET is tur ned on. WHen the midpoint voltage ramps quickly to GND, then the source-gat e capacitance of the high side FET is subjected to high dV/dt, and that cur rent runs out of the gate driver for the highside FET. So if the high side FET driver has non-zere impedance, the gate voltage will rise during the mi dpoint travelling to GND and that is enough to turn on the high side FET wh ich translates into cross conduction. BAD

I don't have that luxury :-)

ed, but then the manufacturer knows well that he can ask for a higher price :-(

Will check them out

Cheers

Klaus

That could be done with one of this tripple inverter tiny logic thingies :-)

How about

(plus a pullup resistor).

Well. To be fair, he didn't say it couldn't be a class A driver.

You'll actually burn more money on the 10 ohm power resistor, though.

Tim

Yes, a complementary emitter follower works well, but Klaus said no discretes.

If it were allowed, a NPN-PNP in one package and a resistor from base to emitter gets you six drivers per 'AC14.

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