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STM32F407 internal I/O circuit

Question asked by robber on Feb 25, 2016
Latest reply on Feb 25, 2016 by robber
Hello everyone,
i have a circuit where 8 I/O (5V tolarant)pins of my STM32F407(supply is 3.3V) are configured as inputs and are tied to 5V with a 10K pull-up resistor. The I/O as inputs work ok but when a configure them as outputs a have a voltage drop 1.7V on the pull-up resistor and current flows inside ...the microcontroller output pin... My question is, where does the current go? is it safe? Please note that i cannot change the 5V pull-up and the pin has to act as input and output due to the rest complicated circuit.
Thank you