ispMACH4000: Does input threshold of an I/O pin will depend on Vcco value?
The short answer is no. The input threshold is ratio based on internal voltages. If device power supply, Vcc, stays within the recommended operating range as specified in the device data sheet, the internal reference voltage remains the same and so does the input threshold. The bank power supply, Vcco, only affects the output signal voltage level and drive strength but has no effect on the input threshold.