NDCU10 powe circuit

Hello
We use the NDCU8 and NDCU10 in our equipment which is realy sensitive to the power noise.

I can see a difference between the NDCU8 which do not perturbate our equipment and the NDCU10 where we can see some perturbation.

the board configuration is
NETDCU10-AN-WCE

Do you have the same Power supply design on both board our is there any changes?

Thanks for the info
An additionnal question which apply on both NDCU8 and NDCU10

It seems our pertubation problem is more related on the RS232 line

Which kind of ground filtering do you have between the input ground and the RS232 Ground

I have seen on the starter kit documentation that the the input ground is called GND and the RS232 ground is called GNDC.
Is there any isolation beetween this 2 GROUND?
Do you supply the RS232 IC with the same +5V input or is it internaly generated?