Hello TI Community,
I just remarked what seemed to be a discrepancy between the recommendation in the datasheet of the ADS1278 (SBAS367F) and the electrical drawing of the evaluation board of this component (SBAU197A).
In the datasheet, it is written the following statement (page 37, point 6):
A 1nF to 10nF capacitor should be used directly across the analog input pins, AINP and AINN [...] Capacitors from each analog input to ground can be used. They should be no larger than 1/10 the size of the difference capacitor (typically 100pF) to preserve the ac common-mode performance.
However, in the last page of the circuit diagram of the evaluation board (page 22, Channels 5-8 Analog Connections), although the value of the capacitors between AINxP/AINxN is compliant with the statement (2.2nF), the value of the capacitor between the analog input and the ground is not (1.5nF instead of less than 220pF).
Is there really an issue here or did I read the datasheet wrongly?
In any case, could you please explain why the capacitor values are not below 220pF?
Thanks a lot for your help