On a dsPIC33 device, with 3.3V power supply, the digital inputs nominally operate from zero to 3.3V. However, input pins that only have digital functions can sustain a 5V input. The levels at which the input pin detect a input high or input low stay the same and are set at values that work for 3.3V inputs. Input pins that have analog functions are not 5V tolerant, and cannot exceed the VDD max specification of 3.6V.