I am using the ADAU1701 DSP and I am passing a full scale input signal (2V RMS) directly through from the external 18k resistor on ADC0 (Pin2) to VOUT0 (Pin46). The issue is that I am finding that the output voltage is 35mV short of 0.9V RMS full scale output of the DAC.
The signal level detector is showing -4dB. If I put in an input signal slightly greater than 2V RMS, the signal meter will go to -3dB etc (see attached screenshot).
I've double checked the hardware. I am sampling at 48kHz. therefore ADC0 and ADC_RES are fitted with an 18k external resistor (+/-1% tolerance) as per the datasheet (see attached schematic snippet).
I’ve also double checked that I am initializing the DAC Setup Register as per page 44 of the datasheet.
That datasheet doesn't specify a tolerance on the full-scale output of the DAC but just states 0.9V RMS as the typical.
Just wondering if the 35mV error that I am getting is within tolerance of the chip or if it is large enough to warrant further investigation of my design?