I ham testing an MIC6270 open-collector comparator but one thing is bewildering me. I am making the following connections:
- V- to GND
- V+ to 12V
- IN+ to GND
- IN- either floating or 5V
- A 20k pullup resistor from OUT to 12V to make the output normally HIGH/12V
What I expected this comparator to do is output 0V when IN- is floating (which it actually does), and then when IN- is connected to 5V (or anything significantly greater than 0V) then the output of the comparator should float and the pullup would pull it high to 12V. However, when I connect IN- to 5V the output still goes to 0V! Since IN- is greater than IN+, shouldn't the comparator output be open because the differential condition is not met?