[sdiy] A/D weirdness

[aankrom]

Try bypassing larger electrolytics with smaller caps, like 0.01uF or 
0.047uF. This helps with higher frequency noise. Small tip, I know, but 
the lower effective series resistance helps.

AA

On Thu, 22 Dec 2011 17:35:08 +0000 (GMT), Karl Ekdahl wrote:
> Hi list, got some trouble with an A/D converter and wanted you guyses
> thoughts.
>
> I'm working with a ADS8326 16-bit super nice converter but i keep
> getting erratic results, the data i get back fluctuates ~+-100 bytes
> (so app. 7 bits) which is clearly way out of range for this 
> converter.
> While testing i've been tying both inputs to GND to try and minimize
> the variables, i've tried both buffered and unbuffered signals. The
> only way i've gotten non-erratic results so far was to tie the
> "ref"-input to GND so i figured it might be the voltage reference.
> However whatever i've tried (buffered through opamp, unbuffered etc.)
> i get the same results - also this reference (a REF5050 divided to
> 2.5V as the ADS8326 is running on 3.3V) is driving a D/A that works
> just great so i guess this is not the problem. I did for a while have
> some issues with not getting the lower bits in due to accidentally
> over-clocking the A/D, however i put in a delay that fixed that 
> issue.
> I tried putting in various delays in the code but to no avail.
>
> So i'm stumped, any help greatly appreciated.
>
> Karl
>
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