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OPA2325: OPA2325 Recovery time

Part Number: OPA2325
Other Parts Discussed in Thread: TEST, OPA325

I need an opamp that can quickly recover from output overload, since the input operates in a larger range than that l am interested in measuring.

From the OPA2325 datasheet, table 6.7, I read overload recovery time 200ns, which would work fine for me, as long that is not (strongly) depending on the amount of overdrive.

Then I look at figure 32 and 33 and I notice that time scale in those plots is in the order o µs.

Question: am I missing something about test conditions or is the time scale of fig 32 & 33 wrong?

  • Yes Franco, pretty hard to make any sense out of this - The plots seem to have a couple of errors, The y-scale should probably be 1V/div and the x might be 100nsec per major div. Also, it implies maybe that spec line is delay for the output to start recovering to a 0V value. Most overload recovery specs would talk about recovering to some % of final (linear) value. Hard to say on this one, 

  • Franco,

    There are typos in the OPA325 datasheet overload recovery time graphs - I have corrected them below.  But please take a note that the gain used in the specification is G=-10 and thus the limit applies only for overdriving the output beyond its rails but not the input; thus there is no overload recovery caused by the non-linearity of the input stage.  Therefore, if you use the op amp in a buffer configuration overdriving both the input and the output beyond their linear range, you should expect the overload recovery time to be longer than the typical 200ns specified in the OPA325 datasheet.