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PCM1807: strange clipping behaviour

geert de vries
Intellectual 580 points
Part Number: PCM1807

In a recent application we have implemented a PCM1807 converter operated in slave mode.

Driving the left  channel only  with 3Vpp, the converter has full scale output on left out as expected. The right channel is at noise level as it is not driven in this condtion.

When we increase the drive level with 3 dB  ( slightly clipping the left channel ) the right channel jumps from -85 to-3dBfs and delivers a heavy distorted

version of the signal which is driving the left channel. I increased the series resistor at the inputs to 4700 Ohms which gives no improvement.

Even when floating the right channel the effect occurs, so this is not happening in the drive stage but in the converter input stage or modulator.

Is there any solution to work around this?

  • 0
    TI__Guru 57800 points

    Hi, Geert,

    This is not a normal behavior for this part, is the issue occurring only when clipping left channel?, Have you tried replicating this issue with a different IC in the same board? is the behavior in left side  the same when clipping right channel?

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    Intellectual 580 points

    I tested an other design using also 1807 this morning. Different board, different chip, same result.

    What you see is the application board routed to Arta analyser via dante interface. One channel (right) slightly overdriven ( third harmonic -20dB), the other channel (left) input not driven however peaks up to -3dBfs feeding through this channel. Next post same picture however 1 dB lower input

  • 0 in reply to geert de vries
    Intellectual 580 points

    Normal situation- one dB lower drive signal. Left channel no input signal results to approx -80dB ( there is some crosstalk...) right channel saturated.