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BJT driver for MOSFET?

J

Jon Slaughter

Jan 1, 1970
0
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
 
J

Joerg

Jan 1, 1970
0
Jon said:
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.

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.
 
J

Jon Slaughter

Jan 1, 1970
0
Terry Given said:
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.

Cool, thanks guys. I might just have to do this
 
J

Joerg

Jan 1, 1970
0
Jim said:
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 ;-)

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.
 
C

Charlie E.

Jan 1, 1970
0
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.

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
 
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