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OPA320: Non Inverting Level Shifter with OPA320AIDBVR

Akhil K R
Prodigy 50 points
Part Number: OPA320
Other Parts Discussed in Thread: TINA-TI

Tool/software:

Dear TI Team,

I have designed a noninverting level shifter using the OPA320AIDBVR, and I am reaching out for your assistance. The design values are specified below, but I have observed a discrepancy between the calculated and actual output values, with a shift of approximately 10-100 mV. To meet my requirements, I need the output precision to be less than 50 mV. I have provided both the actual and calculated values for your reference.

Input Voltage OP-AMP Output Voltage Measured (V) OP-AMP Output Calculated Voltage (V) Difference (V)
-0.705 0.696 0.605 0.091
0.000 1.028 0.958 0.070
1.373 1.662 1.644 0.018
2.477 2.175 2.196 -0.021
3.422 2.612 2.668 -0.056
3.488 2.648 2.701 -0.053

The Vref is 4.992V. R145 is No mount only.

  • 0
    TI__Guru 68511 points

    Assuming Vref=5V, the circuit meets the design parameters - see below.

    For Vref = 4.992V see plot below.

    Below I have attached Tina-TI schematic for your own simulation.

    OPA320 level shifter.TSC

  • 0 in reply to Marek Lis
    Prodigy 50 points

    Dear Marek Lis

    I have compared the actual output values from the op-amp with those calculated by the tool, and I observed a discrepancy. 

    OPAMP INPUT OPAMP OUTPUT Tool Value Difference
    -0.497 0.791 0.707 -0.084
    0.000 1.027 0.957 -0.070
    0.480 1.242 1.210 -0.032
    0.970 1.473 1.460 -0.013
    1.510 1.723 1.710 -0.013
    2.002 1.950 1.960 0.010
    2.510 2.188 2.210 0.022
    3.000 2.412 2.460 0.048

    Can you please check if the OPAMP is having any tolerance issues. My gain is 0.5 here.

  • 0 in reply to Akhil K R
    TI__Guru 68511 points

    You seem to use wrong resistor values for Vref=5.1V - see below.

    Having said that I believe the main reason for the large error you see is the tolerance of the resistor you use. Calculating the gain using your values:

    Gain = (2.412-0.791V)/(3V+0.5V) = 0.463 instead of 0.5

    Thus, using R2 of 14k instead of 16k and R3 of 23.5k instead of 26.7k (~12% tolerance) would result in the error close to what you measure (see below):

  • 0 in reply to Marek Lis
    Prodigy 50 points

    Dear Marek Lis

    Thanks for your support, Now I am able to match my values

  • 0 in reply to Akhil K R
    TI__Guru 68511 points

    Glad to help - good luck with your project!