16 Channel ADC breakout card with serial interface

Hi,

You get 187 ADConversion results per second.

So if you have just 1 channel you get 187 conversion results per second of this channel
But if you have two (or more) channels then you have to multiplex them.
This means: Convert channel 0, convert channel 1, convert channel 0, convert channel 1 ... and so on.
So still the ADC converts 187 times per second,
but only 83 times channel 0 and 83 times channel 1

If you have 48 channels, then it conversts: ch0, ch1, ch2, ch 3, ch4 ... ch47, ch 0, ch 1, ...
Still the Adc converts 187 times per second,
but ch 0 (and any other channel) is converted just about 3.9 times per second. About 4 times per second.

****
Stop reading here if deep AD details are likely to confuse you.

Indeed the "187" is not the sampling rate here.
This is because we are talking about a "DelSig" = delta sigma ADC.
A Delta sigma ADC uses oversampling and a digital modulation filter inside.
So indeed here the 187 is the "data rate". The true sampling rate is maybe 128 times higher ( 187 1/s x 128 = 24k samples/s) .. or much more higher. It depends on the internals of the DelSig.

Other ADCs:
* SAR = successive approximation converter ... typically have no oversampling, thus dataRate = samplingRate
* FLASH ADC .. the same: dataRate = samplingRate
* some audio ADCs use internal oversampling, thus the sampling rate is not the data rate.
(nowadays most audio ADCs are DelSig ADCs)

The benefits of an DelSig:
* cheap
* good linearity
* high resolution
* simple anti aliasing filters
Drawbacks:
* slow
* maybe need additional care when multiplexing input (dummy samples until the internal sigma delta modulator has fully adjusted to the new channel)


Klaus

The conversion rate in this part (PSOC) being discussed, the 12 bit SAR looks like :



Background :




With respect to the DelSig the 187 SPS is the "effective" sample rate. The clock running it
looks like :



Particulars for both found in the architecture manual.

Basic DelSig overview :




Regards, Dana.