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TL074: Active filter failing with TL084, but working with TL084, question about the current needed by the filter.

Part Number: TL074
Other Parts Discussed in Thread: TL084

Hello.

I have the following design in one board:

But the system is failing with all the LM074 that we currently has in stock, and it works with the LM084.

The input of the system is an square signal of 80kHz wich moves between +15V and GND.

The output whith the LM084 is the same as the simulated:

And the output with the LM074 is something that I can't find how to simulate:

Trying to understand more the circuit I simulated, and measured the current AM1, the simulation shows an square current of +/- 10mA

  • Is the TL074 capable of produce this current needed for this circuit?
  • Is the TL084 capable of producing it?, in the datasheet I can't find how to obtain the maximum Iout.
  • Is there something wrong with my circuit that could produce these different output with the TL084 and TL074?

Pd: With webench I could produce some circuit that use the same topology, so I guess that the circuit is fine

https://webench.ti.com/appinfo/webench/scripts/SDP.cgi?ID=ADA47375AE08A8B5 

 

  • Felipe,

    Both TL074 and TL084 can provide 10mA. However, I wonder if the output of the first op-amp and inverting input isn't going out of range during the pulses.

    I do recommend changing to high resistances and low capacitance as there is no need for the currents to be so high.
    Because input and VCC+ are both 15V, is may be good to attenuate the input a little.

    Can you provide the output waveform for first op-amp?