4 Replies Latest reply on Apr 24, 2016 9:22 PM by todor.todorov

    OpAmp trouble - offset too hugh

    todor.todorov

      Hi everyone,

         

      I breadboarded the circuit in the attached picture and got unexpected results from the opamp. The ADC is configured to use the 1.024V bypassed reference in single-ended mode and the input on the non-inverting opamp pin is max 6 mV, so I configured the gain of the opamp to be 147. But when I measured the voltage on pin 1.3 (OP1.out) it was ~ 1.4V instead of the expected ~900 mV - the screenshot of the opamp config is also attached.

         

      When I used an external opamp (AD8629), result was correct: 882 mV.

         

      I am using the CY8CKIT-049-41xx development kit.

         

      So what did I miss?

         

      Thanks,

         

      Todor

         

      PS. The voltage on the output pin was measured with a multimeter ;-)