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OPAX197 Vs= +/-18V, RL=600 ohms conditions. Will it work correctly?

V 666
Prodigy 50 points
Other Parts Discussed in Thread: OPA197, OPA1652, OPA1662

I need to drive RL=600 Ohms with an opamp powered by +/-18V to output voltages exceeding 15-16V(peak). Is OPAX197 the right choice? The datasheet information indicates high output current but there is no data from measurements made at 600 Ohms. There are only 2K results. What degradation of THD+N and headroom should I expect? Does it make sense at all or are these conditions already too hard for this amp?

  • 0
    TI__Guru* 93105 points

    Hi V 666,

    The OPA197 precision op amps will likely deliver at least 15 V peak with a 600 Ohm load and +/-18 V supplies, but we have not characterized the device for this kind of load service. Certainly, the THD+N will degrade because the open-loop gain (Aol) will be lowered by the 600 Ohm load impedance. The only real way to know if it fully meets the performance you need is to test it in your circuit.

    Possibly a better alternative would be to use an op amp that has been characterized in some manner with a 600 Ohm load. Most of  the TI AudioPlus op amps do receive some level of characterization with a 600 Ohm load because that is a common audio load impedance.

    Have a look at the OPA1652 and OPA1662 datasheets and you will see in the Typical Characteristics Curves THD+N for a 600 Ohm load. Then, have a look at the Output Voltage vs Output Current curves and you can see how much output voltage swing they typically produce for the output current levels.

    https://www.ti.com/lit/ds/symlink/opa1652.pdf

    https://www.ti.com/lit/ds/symlink/opa1662.pdf

    This URL will lead you to more of the audio op amps:

    https://www.ti.com/amplifier-circuit/op-amps/audio/soundplus.html

    Regards, Thomas

    Precision Amplifiers Applications Engineering