LM339 with internal pullups

Using Arduino Microcontrollers
#1

Hello,

I have a arduino micro connected with the outputs of the LM339 (open collector opamp). But i have no place for the pull-ups for the outputs of LM339 on my PCB. I have read that there are some internal pull-ups, but shall this work with the arduino and the LM339?

Thanks
Josejos

#2

If the 339 o/p is going to the a digital input on the Arduino, then yes the internal resistors can be use as the pull-ups on the 339.

example:
pinMode(2,INPUT_PULLUP);

#3

For the record.. An LM339 is NOT an Op-Amp.. It's a comparator..
The pin compatible Op-Amp is an LM324.
Note that the output swing is limited to -1.25V from the plus supply rail and +1.25 V from ground for a max of +/- 2.5V, assuming a 5V supply rail...
An LMC660 will swing to ~. .3 - .4V of either rail and is also pin compatible.

Doc

#4