Allow aliasing in AUX ADC (1451/1452)?
I'm using an ADAU1452 at 192kHz sample rate for a project. I'm aware the auxiliary ADC's run at 48kHz regardless of the DSP sample rate. If I try to use these to measure signals up to 96kHz, will this work?
Allowing them to alias is fine for this application (level measurement) but I want to be sure the hardware isn't imposing some other filtering or anything else that might confound this or lead to inaccuracies or odd behavior.
I can run some tests myself, of course, but if I do, and the results are acceptable, can I rely on this to be consistent? I hesitate because (unsurprisingly!) it's not in the datasheet.
Thanks!
Audio Signal Processors
adau1452
aux adc
SigmaDSP Audio Processors
There is no anti-aliasing filter (or other filter type) on the AUXADCs since they are generally used for low frequency control signals. However, a typical audio bandwidth analog filter would be fine if you need the full bandwidth.
As an aside, under the hood, there are not separate ADCs per input. Internally, it is one multiplexed SAR ADC running at 384 kHz. However, being a SAR type, this is transparent. Since there are only six inputs on the 72-pin parts, there are two unused time slots. These are exposed on the 88-pin parts (1463/1467).
Ken
Thanks, Ken. It's still not quite clear if this will work but it sounds likely. I think it all depends on the speed of the sample/hold in the ADC. Clearly it is at least 384kHz, so that should theoretically cover input signals up to 192kHz, so going to half that should be well within the ability of this ADC.
There must be another internal clock running at ~10*384kHz (or higher) that runs the SAR to get 10 bit approximation resolution.
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