OPA2392: Follow up on Input Bias Current question

Part Number: OPA2392
Other Parts Discussed in Thread: OPA392

Tool/software:

Hi!

Just a quick question following up on the bias current discussion. 

I was wondering is you could provide a few more IB vs Vcm graphs for supply voltages close to the 4.25V supply level mentioned.

We would like to use the OPA392 with a supply voltage in the order of about 3.8V to 4.5V and want to see how much we can push it before the bias current exceeds our spec.

Alternatively, if you could provide a spice model that accurately accounts for the bias current vs common mode voltage behavior (the one available does not seem to do that, see the linked discussion), that would also work.

The part seems very promising and we are keen to use it.

Thanks in advance,

George

  • Hi George,

    We also have IB at 3.3 V (+/- 1.65 V) and 5 V (+/- 2.5 V) for multiple devices, see below.  There is an increase in IB around the transition region that is visible at 5 V, but as long as you keep the common mode voltage below 1.5 V from the positive rail, the IB is generally less than 50 fA.

    We do have the IB modeled but not to the detail likely that you are looking for, as you mentioned.  Unfortunately I can't find any data between the supply voltages requested.  

    Regards,
    Mike

  • Hi Mike,

    Thanks for getting back so quickly. I understand that there might not be any data for the supply voltages I was requesting (no worries!).

    Just a small follow-up then. On the previous thread it was mentioned that supply voltages "below 4.25V should mostly eliminate the IB bump". I assumed that this is a conclusion made from available data, but that does not seem to be the case. Could you help me understand how that threshold can be estimated? 

    Best regards,

    George

  • Hi George,

    The 4.25 V estimate was extracted from a circuit analysis of the internal voltages that lead to the IB bump.  Unfortunately we don't have any data to support at that supply voltage.

    We can get IB vs. common mode for a few different supply voltages but it may take ~2 weeks or so if you are interested - let me know.

    Regards,
    Mike

  • Hey,

    This clarifies things. It would be useful to have experimental data on the voltage at which the bump disappears, but we will try and do this on our end.

    Thank you.

    Best regards,

    George