adau1701 ADC input hava white noise

Hello,

It appears from the data sheet settings you're highlighting, that your desired sample rate is 88.2 KHz -- (2 x 44.1 K). To operate this way, tie both PLL_MODE pins low and use a 2.8224 MHz MCLK -- that's (32 x 88.2K). Finally, set the DSP core's Program Length for double-speed operation within the 170x/140x Register Control window inside SigmaStudio:

Selecting the higher sample rates decreases the number of available instructions since the core doesn't have time for more before the next sample arrives -- exceeding about 500 instructions at double rate -- which the compiler may not flag at higher rates -- can cause all sorts of problems including white noise Your DSP core runs at 45.16 MIPS for any of the 44.1 K multiples -- 44.1 K, 88.2 K, 176.4 K. Thus there's no change in the hardware PLL setup (mode pins & MCLK) for any of these -- something which the data sheet IMHO makes rather unclear.

Best regards,

Bob