So I had interfaced a microcontroller (TI CC3200) with a keypad, using a 5V power supply with maximum current rated at 225mA.
Everything worked fine, until I replaced the 5V power supply with a new one that has a bigger maximum current rating of 2A (Same 5V). This immediately burned my chip.
To investigate why this happened, I looked at the datasheet and realized I've made a very simple mistake that I've pulled the input pins to 5V (PORTX-PORTX) on a 3.3v rated microcontroller. VIH and VIL are rated at 0.65 × VDD and VDD + 0.5 V, so no wonder they would burn out.
However, what I don't understand is why the chip didn't burn out on my first power supply, where it was also 5V. Is it because the power supply had a lower maximum current rating? If this is the case, on top of worrying about the VIH and VOH level, do I also need to calculate exactly how much current I need to pull the input pins with based on the value of IIH and IIL? But then if you look at the datasheet, it only shows the nominal values for IIH and IIL, not min/max.
What is the proper way of doing an interface analysis on voltage/current level?