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?
pull up resistors
Mar 24, 2009
2 Replies
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
Sure,
Just make sure the IO pin can sink the amoung of current that will be coming through the pullup resistor and still meet "Vo low" spec.
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