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PCM1804: Balanced line level input for PCM1804

Part Number: PCM1804
Other Parts Discussed in Thread: PCM1822, TAA5242

I'm looking to use the PCM1804 for a balanced line level (XLR) input. Ideally without a negative voltage supply. Should I use an op-amp to add the DC offset from Vcom or can I just capacitively couple the input directly with resistors to Vcom? What is the best approach?

  • Hi Alex,

    Without using the negative supply, the input becomes an unbalanced single-ended input. PCM1804 is an older ADC designed only for fully-differential input signals. If you connect only the positive XLR input to a Vin(L/R) pin and AC-couple the other Vin(L/R) pin to ground you will lose half the amplitude (-3dB) of the input signal.

    To mitigate this, you could implement a circuit such as Figure 44 of the datasheet.

    However, I suggest using a newer ADC such as PCM1822 or TAA5242 that are also hardware-controlled for easy implementation but allow a single-ended input configuration