Do SIO Pins Have Less ESD Protection? | Cypress Semiconductor
Do SIO Pins Have Less ESD Protection?
I have recently got 2 product returns from a few hundred PSoC-containing devices which were sent into the field (industrial devices). In one case, an LED connected to the PSoC wasn't working, and in the other, two cap sense buttons connected to the PSoC were not working.
I've checked all the connections and determined that the microcontroller is at fault. Then I discovered that all these pins happened to be from the same port, port 12, which is SIO only. This got me thinking, because SIO supports a larger voltage range than normal GPIO, do they not have the same ESD diodes clamping the voltage is the positive direction? Thus giving the microcontroller port 12 less ESD immunity and perhaps why these pins are not working anymore.
Note that in both cases, other pins on port 12 were still working, so only the pins had fried, not the entire port.