We use ADuM140D isolator with AD7175-2, meet below issue.
AD7175-2 sets to single channel continue converting mode. We add ADuM140D(isolated SPI+SYNC),sampling rate sets to 25ksps, we catch 4us delay between every data. If increase the sampling rate to 50ksps the delays are not the same(long and short dealys in turn).
Then we check the ADuM140D,we find Do is pulled low for short time and then return to high again(Vdd1 high, Vdd2 high, Vin high, Do high before). We try to change the isolator to optical coupler, AD7175 can work normally.
That's the confuse and hope you can share your advice.