AnsweredAssumed Answered

Input clamp current

Question asked by publius on Jan 22, 2018
Latest reply on Jan 28, 2018 by jeremyzhou



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.