I have a design where I'm using Atmega328P's IO to drive a stepper motor driver. However, I'd like to be able to use an external control logic connected to the same motor driver pins to drive the motors. However, I know that when the Atmega is powered down you cannot have a voltage of more than 0.5Vcc on its IO pins. Hence I thought of using a buffer to isolate the pins as shown in the image below. The buffer's datasheet states that it can tolerate upto +6.5V on its IO when its powered down.
Any thoughts on this?
Any thoughts on this?