Part Number:ADS7947
Hello,
On top of my previous question I got 2 additional questions :
1. Asymmetrial input resistor?
in the datasheet there seems to be a contradiction about the input resistor.
On page 27 it is mentioned :
"The 470pF capacitor across the AINxP and AINxN terminals decouples the driving op amp from the sampling
glitch. It is recommended to split the series resistance of the input filter in two equal values as shown in
Figure 52."
On page 28 there is a table mentioning asymmetrical load where the resistor at AINxN is always 5 Ohms (R1) and the Rsource is totally different
Can you explain why this table got asymmetrical load conditions on AINxP and AINxN?
Can we keep Rsource=R1= 22Ohm (in total 44 Ohm)?
2. Decoupling of REF?
Can we use a simple decoupling capacitor of 1uF on the REF pin connected to a +3V3A (analogue power) plane ? Does it make sense to also insert a 22 Ohm series resistor to make a RC filter with the 1uF(see drawing at the right)? Or is it better to leave this out and keep the left circuit?
Kind regards.
Filip