Other Parts Discussed in Thread: OPA1632
Differential 0dBFS analog input level is specified as 6Vp-p (typical) on the PCM4204 datasheet (9/2004, p.3). Here it approaches 10Vp-p differentially, a greater than +4dB difference, indicating the '4204s input pins need to swing nearly rail-to-rail before 0dBFS is achieved.
Input voltages were confirmed via oscilloscope, audio analyzer, and DVM. Analog rail voltages VCC1 and VCC2 measure 4.99VDC. Digital levels were confirmed via the CLIP3 pin and two different digital analyzers. The attachments show the single ended and differential Vins and an FFT. Vin is 8.1Vp-p with a resulting digital level of approximately -2dBFS. These tests were carried out on our own board, not the TI evaluation board.
Please explain this discrepancy.