SD16 Sampling Rate

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Answer

In General: Fs = Fm/OSR, given on Page 24-7 of 2xx User’s Guide.

In most 16 bit application, OSR = 256 Fm (=f(SD16)) is typically around 1Mhz (The range is given on Pg 44 of 20xx Datasheet)

Now the user needs to decide what resolution (or SINAD) they want by choosing a particular OSR (as given on Pg 45 & 46 of above datasheet)

Theoretically speaking the max sample rate of the SD16_A is: 1.1 Mhz/32 = 34.375 ksps, but then the resolution won’t be as expected.

For best accuracy we recommend highest OSR, which will then put the limit to 4096 samples/sec.

The following is an explanation when using the INTDLYx bits:

Case 1: Single channel, continuous conversion, INTDLY = default (trigger interrupt after 4 conversions). Here the first 3 samples are discarded but only in the first instance after which the INTDLY feature does not apply (all samples generate interrupts). So there is no significant net impact on the sampling frequency.

Case 2: Single channel, single conversion, INTDLY = default. Here for example the SD16 is turned off between successive conversions. Each time we wait for the digital filter to settle. Reducing the effective sampling frequency to 4k/4 = 1k (or the SD16 stays on 4x times longer each time I turn it on).