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OPA564: Is paralleled operation possible

Victor Kviat
Prodigy 100 points

Part Number: OPA564
Other Parts Discussed in Thread: OPA541

My customer needs Class A/B amplifier with BW ~= 1MHz, Vout = 10Vpp, Iout_max = 2.5...3Apk.

I have very good experience with OPA564 and thought about using it in paralleled connection for this application. The OPA564's datasheet says nothing about paralleled topology but I used some other TI's high power opamps (like OPA541) this way with pretty good results.

I think about the following configuration:

- master: inverting amp (OPA564) with G=2 or less (to get full power with Vout = 10Vpp and BW = 1MHz)
- slave: non-inverting buffer (OPA564) driven from master's output
- current sense: 50-100 mOhms resistors
- Power supply 12-15Vdc

I wonder whether such configuration will work for my application.

Thank you.

Victor.

  • 0
    Guru 140200 points
    Hi Victor,

    take care, what works with the OPA541 need not to work with the OPA564. The OPA654 is much faster and has a bandwidth of 17MHz compared to 1.6MHz of OPA541. This can make trouble when the input signal contains steep edges and the outputs cannot toggle at the same time. One cure is to remove any fast slewing at the input by the help of heavy low pass filtering. But this contradicts with your wish to have a bandwidth of 1MHz. See also here:

    e2e.ti.com/.../paralleling-op-amps-is-it-possible

    Kai
  • 0 in reply to kai klaas69
    TI__Expert 6275 points
    If you are trying to get BW ~= 1MHz, Vout = 10Vpp, Iout_max =3Apk remember SR = 2*pi*f*Vopk. For 1MHZ, 5VPk, you need 31.4V/us slew rate. If you parallel power op amps it is recommend that you only use 1/2 the slew rate to prevent high circulating currents between the master and slave. Most datasheets spec only a typical SR. Assume as a rule of thumb a +/-30% tolerance of that slew rate over process and temperature. You will also need to consider power dissipation and thermal design. Look at Apex Microtechnology and see if they have a solution. They have a wide range of high performance power op amps. Not always the lowest cost but performance is never free.
  • 0 in reply to Tim Green1
    Prodigy 100 points

    Hi Tim,

    Thank you for your answer. The situation is clear now :)

    I will have a look at Apex Microtechnology products.

    Thanks