What's the maximum input voltage level on an un-powered device?
What's the maximum input clamp current of an IO?
I personally find the documentation on the input structure of LPC GPIO pins quite unclear.
Most pins are 5V tolerant, but only with Vdd present. But I can't seem to find the voltage levels when vdd is not present (LPC1317), see snapshot from the datasheet below:
In another thread it is mentioned that the input structure is a normal input clamp but that can't be the case due to the 5V tolerant pins.
Also, the input clamp current is not specified both for analog and digital pins.
If I follow the datasheet strictly this means that no signal can be connected to the micro-controller that isn't preceded by something that's on the same supply as the controller.
For example, the 3V3 rail of the controller could be short circuited or starting up while a 5V rail remains 5V.
Thanks in advance.