voltage in Arduino MKRZero

Official Hardware MKR Family MKR Zero
1

Warning: Unlike most Arduino & Genuino boards, the MKRZero runs at 3.3V. The maximum voltage that the I/O pins can tolerate is 3.3V. Applying voltages higher than 3.3V to any I/O pin could damage the board.
Does anyone understand that?

If MKRZero runs at 3.3V And in case Applying voltages higher than 3.3V to any I/O pin could damage the board. in this case Why there is a pin (VIN)5V?it's work as only output voltage, right? .and damage is caused by input voltages by other input devices? please answer me!

2

Hi weal5300,

The 5V output can be useful for powering external breakout boards or shields that require this voltage.

It's necessary to protect the MKRZero's inputs from 5V by using a 5V to 3.3V level shifter, such as the one shown here: 4-channel I2C-safe Bi-directional Logic Level Converter [BSS138] : ID 757 : $3.95 : Adafruit Industries, Unique & fun DIY electronics and kits.