RC Filter for 0-20mA Bricklet

[thicks]

Hi,

 

I am just wonder about the capacitor and resistor that in front of the input of the ADC on the 0-20mA Current Loop bricklet. if I calculate the cutoff frequency I get 1592hz.  Is there some noise that needs to be filtered around that frequency?  Maybe it is not intended as an RC filter and the capacitor is filtering the ripple but the resistance is for some other purpose?

 

Also, I notice that the ADC is grounded with the power source of the current loop device AGND.  What would happen if the ADC chip was connected to the 3.3V power supply ground EP.

[batti]

Hi,

 

there is no specific frequency to be cut out. It is only intended to filter a possible ripple.

 

I'm not completely sure why the ADC ground is AGND. Maybe there was a reason for this, but I did not remember. In fact it might be better to connect the ADC to the 3.3V (digital) ground.

 

Kind regards,

 

Bastian