Hi Ryan, Yes, you will need a specialized part for this. The main challenge would be= if you are sensing near either supply rail, especially the positive rail, = of the amplifier. There are specialized current sense amps for doing this. = If you use opamps you will require really good ones and good resistors. ________________________________________ From: piclist-bounces@mit.edu on behalf of Ryan O= 'Connor=20 Sent: Wednesday, November 27, 2019 5:24 PM To: Microcontroller discussion list - Public. Subject: Opamp selection for PIC ADC Hi guys I want to read a shunt resistor voltage which I expect will range from 0 to 1mV. I=92m reading it with a PIC16F18466 which has selectable voltage refs. If I used the 1.024V ref, I assume it would measure an external input from 0-1.024V with its full 12 bits? Assuming that=92s the case, I could provide an gain to the voltage detected of about 100, or perhaps it would be more stable to use a gain of 50 and the internal x2 multiplier? Anyway, my main question is how would I pick an opamp suitable to operate at this low (microvolt) signal range? Is that something I need a special one for, or would say an LM339 be quite happy to provide accurate gain with input voltages that low? High bandwidth is ideal but not critical for this. Cheers Ryan --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .