Hello
I'm wanted to use an PCA9539 I2C IO expander and power it with 3.3V. The IO's will be connected (sink) to 5V (+resistor of course).
The IC is "5V tolerant".
https://www.nxp.com/docs/en/data-sheet/PCA9539_PCA9539R.pdfNow, i'm asking me if there might be a problem if the PCA9539 is unpowered and that a 5V signal is applied to it's IOs.
Won't the body diode of the internal mosfet conduct? In other words, won't the 5V pass though Vdd to the 3.3V power rail???
![](https://reho.st/self/ea514950fe1a2c7631d14e2c18b4c5ef19000178.png)
![](https://reho.st/self/12b9e96163adef2fc128686deb436789a0bf34e2.png)
![](https://reho.st/self/c9a6ace22ebab0bdfaef57f403a6615fef293598.png)