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TL084: TL084 or TL054 to repalce NCV33274ADTBR2G

Part Number: TL084
Other Parts Discussed in Thread: TL054, , LM2904, TLV4172, TLV4170, OPA4209, OPA4228, OPA4192, OPA4140, OPA4197, OPA4227,

I have a customer named 'Jiangmen Xingjiang steering gear', which engineer used LM2904AVQDRQ1 to replace NCV33274ADTBR2G for motor current sampling, they found distortion in the sampling waveform. I suggested him using TL084 or TL054 instead LM2904AVQDRQ1, would it be the right part NO to replace NCV33274ADTBR2G?

  • Hi Mike,

    I assume from the parts chosen that they need a high supply voltage. The parts you recommended would work and probably won't have the same type of distortion as the LM2904. You could also look at the TLV4170 or TLV4172.

    The LM2904, NCV3327, and TL084 are all fairly different parts - what's most important to them? Bandwidth, Iq, offset voltage?

  • Dear Paul,
    The amplifiers are used to sample Motor current, It might run in really high speed when working, So it need enough high SR and GBW to meet the apllication. GBW and SR are the top priorities they choose amplifiers I think.
  • Hi Mike,

    the NCV33274 is a very fast bipolar OPAmp with 24MHz bandwidth and 10V/µs slew rate. The LM2904 has 1.2MHz bandwidth and 0.5V/µs slew rate. So, when bandwidth and slew rate is an issue in your application then the LM2904 is a rather bad choice.

    The TL084 and TL054 are much faster but are not compatible with the common mode input voltage range of NCV33274.

    Eventually, the OPA4192 or OPA4197 can be used. Or the OPA4140, OPA4209, OPA4228 and OPA4227. All these OPAmps are fast and show low or even very low input offset voltage. But they differ in the common mode input voltage range.

  • Kai,

     Great help!Customer chose LM2904 by his own at first, engineer had applied TL084A samples to test on the board and nothing abnormal feedback to me. I will adopt your tips if any problem exist.Thanks!