AD5940 Clarifying Question


I had a question regarding the multiplexing of various AFE pins using the switch matrix of the AD5940. On page 68, section labeled "AFEx Switches", there is a statement that says specifically that AFE1, AFE2, and AFE3 are only intended as use as switches. Looking at the switch matrix we can clearly see that all of these pins are tied to various analog functionality and could in theory be used as inputs and excitation sources. 

My question is, why does the data sheet seem to communicate two contradictory statements. Can I for example use AFE1 as an excitation source for EIS measurements (the same as CE0) by closing D6 in the switch matrix. 

Thanks for any help, I just want to be doubly certain before I make any assumptions on my design.

  • Hi,

    Sorry for your confusion. On page 68, the statement is out of date. AFE1/2/3 have ability to route to switch matrix, so the figure 32 is correct.

    Please check the source code on GitHub which is mostly verified, so you can trust the code if there's confusion. You can also found macros for AFE1/2/3 that connect to switch matrix and ADC input in file ad5940.h.