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ADC convertion when input 0 voltage

Question asked by colla.ivan on Feb 29, 2016
Latest reply on May 3, 2016 by colla.ivan
Good morning to everyone,

I am trying to understand a possible problem I have with tha AD converter of the SPC56ELxx.
I am working on a board where an input current is used to set an input voltage to trhe ADC converter of the micro controller. 
The ADC seems to work fine: I tested the vlaues in the channel data and they seem right.

But if the input voltage is 0, the AD converter give me a valid DATA, 0x2BB. 

The circuit should  give a voltage proportional to the input current, so, if the current is 0, I expect to read 0 on the ADC channel data.

Is there some characteristic of the ADC converter that I don't know, so that, if the input voltage is 0, it write in the data channel a different value (something like a low treshold)?