Can one use bjt's to drive mosfets without any problem? I know its easier to use a mosfet driver but lets just assume I have a lot of bjt's lying around and need some good use for them. I don't see any probems with this except more components a and harder to setup. Just curious as I don't believe I have seen any bjt drivers.
Thanks, Jon
Yep, I did lots of designs that way. Wimpy CMOS gate followed by a pnp/npn pair and into the gate. The main reason was cost since you can get BJTs for around one cent in large volume. Lots of water will flow down the Klondike until driver chips reach that cost level.
-- Regards, Joerg http://www.analogconsultants.com/
I am doing exactly that right now, in volume, for those reasons. Its far, far cheaper than a $1 driver chip. Of course most drivers also do level shifting, which can be pretty darned handy.....
Another good trick is a gate resistor and a pull-down PNP: Rg across PNP B,E, and PNP C to FET Source. So it turns on thru Rg, and turns off thru the PNP. This is great for any DCM design, where you can afford to turn on slowly, but want to turn off fast.
Cheers Terry
This is hard to beat for 50 cents:
John
Cool, thanks guys. I might just have to do this
A great chip but I wasn't too enthused about its pull-up capabilities. Anyhow, 50c is more cents than 2c :-)
-- Regards, Joerg http://www.analogconsultants.com/
to
Joerg, Did you watch "Dancing With the Stars" last night? I was going to call you and tease you about "never watching TV", but once I hit the couch I stuck ;-)
...Jim Thompson
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| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
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| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
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Yes, I made a full confession somewhere in a newsgroup already, I did watch it. Main reason is that my wife and I have a history of many years of ballroom dancing. I leave the votes to my wife though. Methinks Kristi Yamaguchi might win this season.
However, I won't watch the results show on Tuesdays. Too much fluff.
-- Regards, Joerg http://www.analogconsultants.com/
I bought my wife a digital video recorder a while back, and we love it.
It allows us to deal with all that fluff, easily. And its surprising how many TV shows spend about 1/3 of their time telling you what will be on the show. Grrr. NOT ANY MORE.
plus, of course, I abhor watching adverts. Especially when they shout at you. ICSTR if ads in the US are much louder than programs, but they sure are here.
I am seriously considering buying a few more, one per channel (not many channels here) so we can record pretty much everything, and never watch regular TV again. Not that I watch much, ads annoy me too much so a fluff around on usenet instead :)
Cheers Terry
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Ah, the joys of DVRs! I tape the results show and take my bath/shower when the results show comes on. Then, I can watch the whole thing in about 15 minutes... ;-)
Charlie
I have been using this one for well over 15 years:
It is dual - I see it at around 60 cents/1000+ at Digikey, I think I used to get them cheaper than they are now a few years back (but I am not sure).
Dimiter
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