TCA9539： Do unused input ports of TCA9539 need to add pull-up resistors?

Hello,

If you have unused pins P00-P17 in design, I recommend a pull-up (or pull-down as desired). Leaving input pins floating would cause meaningless INT signals, as the device would detect state changes consistently.

If this is impossible for some reason, a software/alternate solution would be to set these pins as outputs at startup, but this may be less robust and may also increase the device's current consumption. Be aware that the P-ports are configured as inputs by default after startup or reset.

Digital inputs such as A0, A1, and RESET should never be left floating.

Best,

Danny

ok