What is the output data update rate when the AD779x is used with a master clock other than 64 kHz?
These devices have 16 selectable output data rates from 4.17 Hz to 470 Hz. These frequencies are determined by the master clock. When the master clock frequency is changed, the output data rate will scale with the applied clock. For example, the default output data rate equals 16.7 Hz when the master clock equals 64 kHz. If the master clock is reduced to 60 Hz, the output data rate is reduced to
(60/64) x 16.7 = 15.66 Hz.
Changing the output data rate will also affect the filter notches. When the output data rate equals 16.7 Hz, there are notches placed at 50 Hz and 60 Hz. If the master clock frequency is reduced to 60 kHz, the 50 Hz notches is moved to 46.87 Hz and the 60 Hz notch is moved to 56.25 Hz.
The data rates given in the data sheet are approximate. For accurate timing, you need to refer to the spreadsheet "AD7785-AD7792-3-4-8-9_filter_model.xls" provided on the AD website.
Nevertheless, as I discuss in my question ez.analog.com/thread/37840, there seems to be an error in that spreadsheet. I think the denominator in the sampling rate formula should have an offset of 8, not 7.
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