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pull up resistors

P

panfilero

Jan 1, 1970
0
I have a basic question about interfacing ICs or using ICs to drive
something... if I have an IC that can source a little current and I
need it to drive something that requires a little more, can I use a
pull up resistor here? And my IC is not open-collector... the pull up
resistor thing makes sense to me with an open collector output... but
what I'm wondering is... are pull up resistors only used for open
collector outputs?
 
R

Rich Grise

Jan 1, 1970
0
I have a basic question about interfacing ICs or using ICs to drive
something... if I have an IC that can source a little current and I
need it to drive something that requires a little more, can I use a
pull up resistor here? And my IC is not open-collector... the pull up
resistor thing makes sense to me with an open collector output... but
what I'm wondering is... are pull up resistors only used for open
collector outputs?

Well, notwithstanding this is properly a s.e.basics question, a pullup
on a normal totem-pole output will do no harm. If you need MONGO source
current, then invert the logic and use a 4.7K or so to the base of a PNP
transistor, with the emitter to Vcc+, and another resistor of, say, 10K
from the base to the emitter. Of course, the output is the collector. ;-)

Have Fun!
Rich
 
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