Gary Lynch

K10: What voltage range can the analog inputs withstand?

Discussion created by Gary Lynch on Jul 8, 2016
Latest reply on Jul 13, 2016 by Fang Li

We have a K10 design where under certain circumstances the voltage reaching the ADC inputs can exceed the VREFH levels and would like to know if this will cause damage, cause the ADC to mis-operate, or inflict other consequences.


There is a table on page 11 of the data sheet that indicates "analog input voltage" can only go up to Vdd + 0.3 V, but it is punctuated by a footnote. Under the footnote we read:
  "Analog pins are defined as pins that do not have an
   associated general purpose I/O port function."


We aren't using any of those inputs: all our analog inputs are multiplexed with digital inputs. There is missing text in this data sheet. If I were to fill in the blank, I would assume that analog inputs that share a pin with digital inputs are digital inputs, and the same table allows them to accept up to 5.5 V, which would solve my problem.


I hate to base my design safety on a sentence that isn't there. Has anyone found an unambiguous spec?