What is the maximum value of positive injected current in 3V compatible I/O for STM32L476 micro. Also what will be the maximum allowed input voltage in Pin when Vdd is 0V.

[TDK]

See Absolute Maximum Ratings in the datasheet.

https://www.st.com/resource/en/datasheet/stm32l476je.pdf

[sam_niraj]

Ya but the datasheet specifies 0mA positive injection only for 3v and 5v tolerant pin, and specifies NA for ​for other . What does NA means

[sam_niraj]

Also suggest, if the maximum injected positive current is 10uA for contiunous period if 8-10 hrs, would it still effec​t the reliability of GPIO

[T J]

I think current will flow into the pin when Vdd is at 0V, trying to pull up the processor Vdd

My solution would be add a 1k or 10k resistor in series on those pins to limit the current.

or a buffer chip like LVC244 that is powered by the same Vdd

[TDK]

Isn't your question about 3V compatible pins?

I don't have any more info than you do. If the datasheet says +0 is the limit, that's what ST guarantees. +10uA would be over the limit. You're certainly welcome to test it in your own application and, if successful, decide if the risk is worth it for your application.