Andreas Werner

GPIO Protection - High Voltage Input Circuit

Discussion created by Andreas Werner on Jun 6, 2018
Latest reply on Jun 24, 2018 by Hui_Ma

Hello all,


(Device: LPC1778fet180)


we want to connect a data line with a high voltage level (above 5 V) to P1[1]. To keep the circuit as simple (and cheap) as possible we have the idea to use a serial resistor - to limit the current - and the protection circuit on the chip - which limits the voltage.


  1. Is it allowed to drive the input with a current source and let the protection circuit "adjust" the voltage?
  2. If yes: Wich current is allowed?
  3. I fond in the datasheet the value I_latch (I/O latch-up current). What is the special meaning of it (What current under which condition)?


Thanks in advance,