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INA1650: Using ina1650 as pcm5242 differential output receiver

Denis Mikhalsky
Prodigy 20 points
Part Number: INA1650
Other Parts Discussed in Thread: PCM5242, TINA-TI

Hi,

I'd like to use ina1650 to receive differential signal from pcm5242 and convert it single ended output. I am using the schematic provided in Fig58 of the datasheet.

Instead of XLR connectors I plan to get a signal directly from pcm5242 output.

Do I need AC-coupling capacitors (C1-C4) in this case?

And if yes, what\s the optimal TYPE of the capacitors? I am choosing between smd ceramic and TH bipolar electolytes

  • 0
    TI__Expert 6400 points

    Hi Denis,

    It depends on your power supply condition and the output common mode configuration of PCM5242.

    If you would like to eliminate ac-coupling caps (C1-C4), it is necessary to use split power supply for INA1650 and VREF mode for PCM5242 or single supply and another supply voltage for VCOM and VCOM mode for PCM5242.

    If it is difficult to choose both cases, ac-coupling caps are needed on the front of INA1650.

    Regarding the cap type for audio application, now you can also choose large smd film caps from some manufactures such as Kemet, Rubycon, or etc.

    Thank you and Best regards,
    Iwata ETsuji

  • 0 in reply to Iwata Etsuji
    Prodigy 20 points

    Thanks. I've created a breadboard prototype that works from +12v single power supply so the next question is on power supply voltage:

    If I understand correctly, at 3.3v pcm5242 outputs differential 4.2v RMS signal that has 6 vp-p amplitude (each signal is 2.1v rms and 6vp-p, but since there are two of them, the final signal is 4.2v rms, but still 6 vp-p)

    What happens after the signal is get processed by ina1650? My understanding, it is summed up and converted to single ended 4.2V rms, but with 11.87 vp-p.

    Is this correct?

    If this is the case, am I ok with 12v single supply as output signal would be almost 100% rail-to-rail? Or do I need dual +12/-12v power supply? 

  • 0 in reply to Denis Mikhalsky
    TI__Expert 6400 points

    Hi Denis,

    I will prepare some simulation files for you.

    If you have not installed TINA-TI yet, I would recommend to install it.

    Thank you and Best regards,
    Iwata Etsuji

  • 0 in reply to Iwata Etsuji
    TI__Expert 6400 points

    Hi Denis,

    I will attach some simulation files in TINA-TI.

    5127.INA1650Vs12V+PCM5242Vref.TSC
    0820.INA1650Vs12V+PCM5242Vcom.TSC
    3000.INA1650Vs+-12V+PCM5242Vref.TSC

    While, please note that, the output from INA1650 is 4.2Vrms when PCM5242 generates 2.1Vrms output.
    Therefore, in the case of the single supply condition, 12V supply is not enough to drive INA1650 output without clipping.

    Thank you and Best regards,
    Iwata Etsuji