[sdiy] A/D weirdness

[ASSI]

Am 22.12.2011 18:35, schrieb Karl Ekdahl:
> So i'm stumped, any help greatly appreciated.

Well, that would only be 4mV of noise on the voltage reference or supply 
noise that is getting through with an equivalent of that.  I can't find 
the PSRR figures in the datasheet, but there is mention of the part 
being very susceptible to supply noise and I'd take that seriously.  It 
is not easy to clean up the supply and reference of a 16bit A/D to 
actually get the performance that is on the label... anyway when you say 
that your reference is shared with other circuitry, that seems to imply 
a good deal of wiring that could be picking up noise.  Voltage 
references should never be distributed like that if possible.  If you 
absolutely need to share a reference, put it closest to the part that 
needs the cleanest reference.

-- 
Achim.

(on the road :-)