Hello,
In my system I'm seeing -54dBFS from PCM1804, which I believe to be excessive. I'm reading this level inside the DSP software, the noise disappears when the relevant serial port is disabled which narrows down the source of the noise to the PCM1804.
The PCM1804 is configured as a slave to the DSP, changing the PCM1804 to be the master improves the noise reading by 6db to -60dBFS.
I get good performance from my DAC so I don't suspect jitter.
Analog input circuity is largely as in the datasheet, 10nF at the input pins with appropriate feedback cap on the preceding op amps.
BCLK and LRCLK signals look good on the 'scope. Triggering on MCLK signal I obtain stable traces for BCLK and LRCLK which I believe indicates they are synchronous.
Decoupling is as recommended in the datasheet, with extra ferrites (supply side of decoupling caps).
I have tried replacing the device but get same results. It does generate some heat, more than the PCM4104 I have in the system, perhaps relevant?
Can anyone help me to track down the problem please?
Thank you.