Best way to connect opamp output to opamp input on different PCBs

Status
Not open for further replies.

eyAyXGhF

Member
Hey everyone,
this seems pretty simple but I'm struggling with it. Easiest explained in the attached photo:
 

Attachments

  • adclocationproblem.png
    23.3 KB · Views: 136
The opamp output on the left side is an extremely low impedance at low frequencies so connect it directly to the input of the opamp on the right side.
The opamp output on the left side can directly feed many opamp inputs on the right side then why do you need the buffer opamps on the right side?
Resistors are not needed.
 

I tried to keep the problem simple for sake of the forum post. The more detailed answer is that the second op-amp stage is being used as a clamp/voltage-limiter before an ADC input to protect it from any possible over-voltage - it is a rail-to-rail opamp powered by a VDD of the maximum input voltage of the ADC. That's why the other stage is needed.
 
Do you need the voltage divider so that the input of a rail to rail opamp is not damaged?
Your post is very confusing since the opamps have no power supplies and a TL074 is not rail to rail.
 
Do you need the voltage divider so that the input of a rail to rail opamp is not damaged?
Your post is very confusing since the opamps have no power supplies and a TL074 is not rail to rail.

Yeah sorry, I just quickly drew that up just to show locations of the op-amps and basic setup. I didn't think that the type of op-amps or their power connections had anything to do with best practice for where an output resistor should go between op-amp stages.
 
If the left opamp is all rail-to-rail with a 5V supply then it can feed all the ADC inputs. Then the resistors and other opamps are not needed.
 
Ignore all the bs about the quality of the schematic or the quality of the question. I get what it is you're asking and there are definitely right and wrong answers. Since the schematic indicates that this is a problem to be solved, why don't you first tell us your answer, or at least your analysis of the problem?

ak
 
If the left opamp is all rail-to-rail with a 5V supply then it can feed all the ADC inputs. Then the resistors and other opamps are not needed.

left op-amp is powered by +/-15V right opamp is rail-to-rail and powered by 3.3V/GND. ADC maximum input is 3.3V. I appreciate you trying to simplify my mock schematic by wanting to remove resistors, but just assume they're there for a reason.
 
Thank you for telling us the important details but why not in your first post?
 
Status
Not open for further replies.
Cookies are required to use this site. You must accept them to continue using the site. Learn more…