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OPA2228: Offset counterbalance

Laszlo Garab
Intellectual 965 points
Part Number: OPA2228
Other Parts Discussed in Thread: OPA228

Hello,

I would like to use OPA2228 and it has offset voltage on the application limit. I got the idea to select such package which has the offset of the two amplifier counterbalance each others. If I buy for example ten package will I find two which has this properties ( even if it is not counterequeal, but the two amplifiers has + and - offset )?

LAszlo

  • 0
    Guru 140200 points

    Hi Laszlo,

    yes, of course, you will find chips with offset voltages of opposite sign. But for statistical reasons you cannot be sure to find exactly two of them in a lot of ten Relaxed

    Kai

  • 0
    TI__Guru 60111 points

    Hi Laszlo,

    This is offset voltage production distribution chart. Approx. 16% of parts will have very low Vos (near zero). As Kai pointed out, statistically, your chance to get two OPA2228s with equal and opposite Vos figures are small in 10 pieces (but you could be lucky as well). 

    Best,

    Raymond

  • 0
    Intellectual 965 points

    I thought not exact opposite offset voltage, that is why I mentioned counterbalanace.

    In my case ADC has LSB 100uV and OPA228 has an offset voltage of 75uV max. If I found a package, for example, -25uV and +60uV, that is great; because in a unity gain application this means +35uV which is less than 50uV as LSB.

    Thank you for calling my attention to the distribution diagram, if I understand well even from 5 package I will find one fulfills my requirement. The question is much more on what is the situation in dual amp package case; because, the distribution can be shifted, for example, production purposes.

    Anyway, on a breadboard with DIP package (in my interest) takes 10 minutes to test it.

  • 0 in reply to Laszlo Garab
    TI__Guru 60111 points

    Hi Laszlo,

    Ok, I see. I am going to close this inquiry for now. 

    If you have further questions, please let me know. 

    Best,

    Raymond