Could you please provide the AD8606 bias current vs. the common mode for 5V?
For example, here's figure 11 from the AD823A specs:
Thanks for your help,
Keep making these excellent OPAMPs!
What kind of circuit are you building that requires this rather than just doing a worst
case calculation with the max number from the spec table?
Also, you will get a big increase with temperature due to the ESD diodes.
Worst cases shown in the table is specify for CM=VCC/2 as states in the table header.
AD8606 is specify as I/O R2R OPA meaning that I can work close to each of the rails. It quite suspicious that Analog-Devices omit Ibias vs CM while giving this info for all other R2R iput OPA I know of...
Nothing nefarious going on. I resent your accusation.
Having been in the precision op amp group five years ago, I can comment on
how data sheets are done and what can vary. BTW, the high speed op amps are in a separate group, and
if you compare data sheets, they are quite different. What goes on a d.s. in the spec table and also which
graphs are done, is a decision by the apps engineer and the marketing engineer. Because of the varied
backgrounds, there was some variation from d.s. to d.s. Finally, about seven years ago, the apps manager
did try to standardize on what was in a data sheet. The AD8606 came out 15 years ago.
You will notice on the old data sheets, voltage noise vs. frequency was on a linear scale due to the piece
of test equipment used. It's much more useful to have it on a log scale, so all of the newer d.s. are log.
You will see variation from part to part. Obviously, a micro power op amp with a supply current of 10uA
will not have RL = 600 ohms, but parts focused on use in audio apps will.
Some of the newer data sheets have over 60 graphs. If it's two weeks before the end of the quarter,
and 58 graphs are done, guess what happens. (We'll add the other two when we rev the d.s.)
You did not answer my question about why you cannot use the max number in the d.s. for -40 to +85
in your calculations??
As I've wrote before:
Worst cases shown in the table is specify for CM=VCC/2 as stated in the table header.
Usually due to ESD diodes and other effects, bias current is higher for CM close to rails.
So I repeat my question again... could you please provide the bias vs. CM voltage or at least specify what's the expected bias current when CM equal to VSS or VCC...
Please help me...
Noam, we have looked for the data in our archive but it is not available. We agree the graph is useful, and may add it in the future. Yes, the bias current will be higher when the Vcm in near the rails as well as higher variability with temperature and part-to-part.
If you need bias current within ~pA range over the full operating range, please use a lower bias current part, the ADA4530-1 for example. Thank you!
We will be collecting the Ibias vs.Vcm data for the AD8606 and it may take some time. I will let you know once it is available. Thank you for your patience!
Thanks for your help.
I really like to stay with the AD8606 and pay 10% than the superior ADA4530-1.
More profits to me... less to ADI :-)
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