Hi,

A little thing I do not understand :

I have a 4.096 voltage ref for ADC
Input sees a LM335 , through a 10k/.22µ L.P.F., powered from 5 v with a 2.2k series resistor.
Wiring to lm335 is ground shielded.

Everything has worked fine for 25+ hours ... ( reading Ok ... etc,etc ...)


Now,

An ADC input overflow has occured ( logged by the system ) that should NEVER had happend ... and the ADC result now is DIVIDED by 2 !!!

a ( say many ! ) system reset did not change anything ...


I took the chip off to read its logging values and just rewrote the "wrong logged" data. ( NO change to the program ).


Pic placed Back to its place ...

ISSUE has disappeared... everything fine again.



Soooo ...

Is there some limitation on ADC input voltage relative to the ADC Vref ??? ...

Yess ... Parameter A25 ( Midrange data ) says ... Vref + 0.3v !!! , that seems logical not to input more than what can be read, ... but no such issue specified ...

Alain