Are XC9500 inputs 5 volt tolerant when Vccio is 3.3 volts?
Yes, 9500 inputs are 5 volt tolerant when Vccio is 3.3 volts.
The voltage level of Vccint is applied to the internal logic of a 9500 CPLD.
Vccint should be between 4.75V and 5.25V for commercial devices and between 4.5V and 5.5V for industrial grade devices.
The input clamping diodes of the 9500 CPLDs are controlled or connected to Vccint. Therefore, any input voltage between 2.0V
and (Vccint + 0.5V) can be used to represent a logic high input voltage. This is independent of Vccio.
The voltage level of Vccio may be either 5V or 3.3V. Vccio controls the output voltage level.
If Vccio is 5V, VOH will be approximately 4V.
If Vccio is 3.3V, VOH will be approximately 3.3V.