1928 - [Power Manager 2] Do the I2C inputs on the ispPAC-POWR1014 have hysteresis?
Yes, a small amount of hysteresis (300mV) is designed into the inputs to increase their noise immunity. The logic thresholds are centered around ~1.4V when VCCD is powered from a 3.3V supply.
Despite the presence of hysteresis, it is still important to minimize noise introduced into the I2C inputs, as hysteresis is not a cure-all for poor signal integrity. In the case of the SCL input, this is especially important, as this input has very low propagation delays (~ nanoseconds) into the chip's internal logic. The SDA input will be somewhat less sensitive to spurious noise because of an internal delay block required for timing compliance with the I2C specification.