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OPA227 biasing requirement

RAJESH KUMAR
Prodigy 90 points

Other Parts Discussed in Thread: OPA227, OPA197

Hi,

I am planning to use OPA227 in my application to attenuate a single ended signal.

As this support is wide supply input range from 5V - 36V (+/-2.5V to +/-18V)

Can I bias this opamp using +5V Dc supply on pin#7 - V+ and connect GND on pin#4 - V-?

I don't have -ve supply on my board, so basically I want to bias this with +5V supply, if not possible please suggest me single supply op-amp which can take 5V or 12V.

Best Regards,

Rajesh

  • 0
    TI__Intellectual 2165 points

    Hi Rajesh,

    The OPA227 requires a minimum supply voltage difference of 5V. This means that you can indeed use this part with a single +5V supply and V- shorted to GND. However, you must be aware of the common mode input limitations of the OpAmp. The OPA227 is specified with a Input Common Mode voltage of:

    (V-) + 2 to (V+) - 2

    Since your V+ is 5V and V- is 0V, you will get an input voltage swing from 2V to 3V. Which means that input voltages outside the 2-3V range will be clipped at the output.

    Please take a look at the TI Precision Labs videos series on OpAmp input and output limitations that discusses these topics in more detail:

    I hope this answers your question!

    Best Regards,

    Mihir Gupta

    Field Applications Engineer,

    Texas Instruments

  • 0 in reply to Mihir Gupta65
    Prodigy 90 points

    Hello Mihir,

    Thanks for the clarifications.

    Do you have single supply op-amp which can work in the range of 5V -12V DC, I could find one OPA197 which works in both single as well as dual supply. However I was looking for op-amps which takes only single supply voltage.

    Regards,

    Rajesh

  • 0 in reply to RAJESH KUMAR
    TI__Intellectual 2165 points

    Hi Rajesh,

    The OPA197 could also work on a single supply up to a V+ of 40V. In general, any dual supply OpAmp can work on a single supply as long as the minimum operating voltage (difference between V+ and V-) requirement is met. However, as I mentioned earlier, your supply voltages will affect your input and output voltage swings. So depending on your supply, you will have a limited range of input and output voltages, which are not necessarily at the same level as the supply voltage rails. This is explained in the TI Precision Labs video series that I linked to above.

    Regards,

    Mihir