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PCM1804 Application Circuit for Single-Ended Input

SS Oak
Prodigy 95 points

Other Parts Discussed in Thread: PCM1804, OPA2134, OPA134

1.  My customer has searched other applications and found many supplied the OP amp with +/-5V in front of many high-performance ADC. And he sketched me his intended circuit as follows. However, I believe the PCM1804 receives VIN that swings in the 0~5V range. Because the positive input(accordingly the negative input as well) to the OPA2134 is biased by VCOM of 2.5V. See page 30 of the PCM1804 spec. OPA2134 portion is depicted as if it is supplied by +/- voltages. Please advise quickly if blow sketch makes sense. They prefer using a +5V only.

 

 

cid:ZPZQ39MRZQS8@namo.co.kr

 

2. The customer wants recommendation for a small yet good performing OP amp. Will OPA134 work?

 

3. What is the problem when the PCM1804 AVDD is supplied with 3.3V? Any trick to use such way?

 

 

  • 0
    TI__Mastermind 28140 points
    Hi SS,

    1. It seems your pictures did not come through, but you are correct that the PCM1804 takes input from 0-+5 V with a reference of 2.5V.
    2. Since i can't see your proposed input circuit i can't say for certain which OP amps will work, and I'm not sure if you meant OPA2134, or OPA134.
    3. This part cannot run with AVDD at 3.3V, if you would like to run at this amplitude you could try the PCM186X series.

    Justin
  • 0 in reply to Justin Bohr
    TI__Prodigy 95 points

    Hello Justin,

    Thanks for the reply. This is my great first experience of Q&A through E2E.

    1. Sorry for not getting you to the picture but you seem to have correctly got what I meant. Given your advice, the OAP2134 application part tranfering the single ended into the differencial, infront of the PCM1804, can actualy be supplied just with +5V on V+, leaving V- to GND. Am I right?

    2. Though the application schematics in the specsheet uses OPA2134, customer wants to try OPA134. Will this be a good choice?

    Thanks for taking the time for these questions.

    Regards,

    SS