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OPA1655: Confused output V vs I plot?

Part Number: OPA1655

Really nice new part, looks like some high speed folks might have contributed - however, these two plots look odd, I use these plots to estimate a linear output current entry for the parametric database. Usually a 0.5V drop off of zero output current voltage is where I set that (Isc is not linear output current available) Anyway, +/-15V supplies will not support a +/-18V output even with zero Io. Assuming this plot was for the max rated +/-18V supply, the specs show a 0.25V headroom required - which I would call RRout, but the plot seems to show 18V. Small issue there, but the plots should be labelled +/-18V supply probably. Oh, and I entered this as a 25mA linear output trying to read about a 0.5V drop off of no load output swing, which means is no longer RRout approx. 

  • Michael,

    The claw curve data was taken at a supply of +/-18V.

    Best Regards,

    Chris Featherstone

  • Michael,

    Adding to Chris' comments, in addition to +/-18V rails used, you are correct that the Vout vs Iout plots should NOT show Vout at its rails at Iout=0 (quiescent condition). According to OPA1655 datasheet table for 2k load linear range is 500mV from either rail (AOL condition) and the output is fully saturated 250mV from its rail.

    Thus, at 25 deg C Vout vs Iout graph should look like the one shown below in blue.