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opAmp

ikram ezzeri
Prodigy 10 points

Other Parts Discussed in Thread: OPA2541

Application is to Amplify a 0-10VDC input signal to 0-72VDC @ 2A. Looking for help with part selection. 

  • 0
    Guru 319890 points

    There are several power op amps that can do 70 V, but the only 72 V device is the OPA2541. Please note that it is not a rail-to-rail device, so you will need wider supplies. And the safe operating area might be too small for you. Can you tell us more about your application, especially the load? Do you need to source or sink current? How are voltage and current related?

  • 0 in reply to Clemens Ladisch
    Prodigy 10 points

    The load is purely resistive and we are sourcing current. 

    The safe operating range of this does not look to be suitable for our needs as VS is 72VDC and VOUT can range from 0-72VDC. 

    We don’t necessarily need to be rail to rail for this but the Voltage would need to come close to the rail (within 1VDC ideally)

  • 0 in reply to ikram ezzeri
    TI__Mastermind 27088 points

    Ikram,

    I agree with Clemens.  The OPA2541 is closes to your requirements.   For high voltage / high current amplifiers it would be unusual to find a device that swings within 1V to the supply rail.  Internal drop on the output transistors normally limits the swing a few volts from the supply rail for high current, high voltage devices.  You may need to adjust your requirements (i.e. a higher supply).  In any case, OPA2541 is the closest device to your requirements.  

    Best regards,

    Art

  • 0 in reply to ikram ezzeri
    Guru 319890 points

    So your load essentially is a 36 Ω resistor? In this application, the opamp would need to dissipate 36 W in the worst case. This would be just inside the SOA, if you have proper cooling.

    Using an opamp to drive a P-channel MOSFET could work, but this would require a rail-to-rail opamp, which does not exist for 72 V.

    To reduce the power dissipation in the driving device, it might be possible to use a buck converter. Would your application be sensitive to switching noise?