Op amp's

gtx15 · Joined: 19 May 2018 Posts: 27

Trying to use Pic's with built in op amps, but i seem to get digital noise on outputs. Am I asking too much from these built in op amps? using them as a microphone amplifier.

temtronic · Posted: Fri Aug 02, 2019 8:31 am

You need to post which PIC you're using as well as the 'microphone' specs. As for low level 'analog', board layout, component placement and selection, power supply parts (esp. filtering) and ground bus all play an important part in getting it 'right'.
Info on what the circuit is suppose to do would be helpful. Is the opamp just 'stand alone' or feeding the PIC's ADC ?

Ttelmah · Joined: 11 Mar 2010 Posts: 19538

As a comment, the op-amp has the limitation that the input needs to be
between Vss, and usually a volt or more below Vdd. So you can't connect
an AC source like a microphone, without first applying a DC bias to this.
Tell us the PIC involved?.
Post the input circuit?.

temtronic · Posted: Fri Aug 02, 2019 5:38 pm

I went through my usual PICs and none have discrete opamps. Got me wondering WHICH PIC the OP is using. Several have analog comparators..but that's a special breed of opamp.
just curious, like my cat...
Jay

Ttelmah · Joined: 11 Mar 2010 Posts: 19538

There are quite a few of the newer analog 'targeted' PIC's that have
OP-amps. Start with the 16F527, then the 16F1703, and all their other
family members. There aren't any that I know of in the PIC18's,
then some of the PIC24's like the PIC24FxxKM20x and some of the
DsPIC33's.