Other Parts Discussed in Thread: TLV3401, TLV3501, LMV7235
I have a customer that is seeing the following issue with the TLV3402:
There is a glitch at 25 ms where the OUT signal is pulled down. The output is pulled up with a 10 kOhm resistor. We observed this behavior consistently at -40 C but also sometime at room temp.
This is how it is configured:
Vcc is tied to +2.7V rail.
IN+ is tied to a +2.048V voltage reference (REF3320AI) with a 100 kohm resistor.
IN- is tied to the output of an opamp (TLV2401I) that is monitoring a 60 Hz signal with a 47 kohm resistor.
OUT is pulled up with a 10 kohm resistor to +2.7V. OUT is also tied to an inverter input (74LVX14) through a 499 Ohm resistor.
The waveform I sent has the +2.7V rail (Vcc). As for the IN- glitch, this is actually caused by the output of the comparator which drops before the glitch on IN-. As for the unused comparator, we tried tying one input high and one low but this did not correct the problem.
They have removed the part from the application, but I am wondering if this is “glitch” is something that we have seen before. They say the new comparator is not showing this issue. It would seem to me that something else is happening, but there does not appear to be any issue with the pull-up voltage. The (+) and (-) inputs do not seem to ever reach the point where the output would change and yet you can see from the scope shot that it is indeed happening.
Thanks for your help with this!
Richard Elmquist