**Part Number:**PCM6240Q1EVM-PDK

Hi,

I have some doubts about ac-coupled rext calc, please help to solve, thanks.

1) What’s the attenuate factor at first stage? And I couldn’t find the specific value in the datasheet.

2) PGA amp INCM is 1.35V in the differential table.

Why it is the same as the single-ended table? Whether using 1.35V/2 is be more reasonable in the differential application? If you have more detailed data, please share it for me, thanks.

3) R tolerance (in %) is 0.8.

Why this value is 0.8? The accuracy of commonly used resistor is 1% or 5%, is the R tolerance 0.95 more reasonable?

4) swing margin (in V) is 0.2V.

What is the definition of swing margin? 10Vrms or the value we expected(for example 5Vrms) between the max differential input value and 14V or 0V?

Why the swing margin select 0.2V? Is this value little small?

In our practical design, the max differential input is 5Vrms, and the micbias is setup 9V, but I couldn’t know how to select the pull up resistors and how to setup the PGA gain. Thanks very much.