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PCM1792A: Does it need unity gain stable opamp for I/V and LPF circuit?

Alex Lee
Prodigy 140 points
Part Number: PCM1792A
Other Parts Discussed in Thread: OPA2228, OPA1656, OPA1692, NE5534, PCM1792, OPA227

Does it need unity gain stable opamp for I/V and LPF circuit? 

We don't need gain in it. (keep 2 V rms, Stereo)
Is is okay to use OPA1656 / OPA2228 for I/V and LPF? Or it has to be OPA1692(unity gain stable)?

Thank you!

  • 0
    TI__Mastermind 19340 points

      Hello, looking at users guide and data sheet for PCM1792 , they are using NE5534 but you can use any comparable OPA. for example according to  OPA227 data sheet, When using the OPA227 as a unity-gain buffer (follower), the input current should be limited to 20 mA which is okay in this case.

    As far as stability at unity gain goes, if you compare fig15  for opa1692  and figure 35 in OPA1656 , they both show the phase margin for unity gain  (G=1) at different capacitive loads. OPA1656 has a good phase margin (about 60 degree) for G=1.

    I highly recommend  you to download the TINA or PSPICE models for these 2  amplifiers and simulate both in your configuration and see the result for yourself. you can use a current source to mimic the output of current DAC.

    Arash