2020-09-23 12:13 AM
Hello ST Community,
I'm planning to use the USB communication with a STM32H743ZI. Then, I will have to use an external power supply, since it doesn't have VDD50USB input. Furtherore, I will power this MCU with a 3.3Vcc. power supply.
However, I read in the AN4938 (Getting started with STM32H74xI/G and STM32H75xI/G hardware development) the following statement:
"During the power-on and power-down phases (VDD < VDD minimum value),VDD33USB should always be lower than VDD".
If I connect directly the VDD33USB to the VDD, I won't be compliant with this recommendation. What would be the consequences during the power on/off? Is there a risk that the USB communication fails?
In any case, would there be a power management IC that would you suggest to use if I wanted to be compliant with this recommendation?
Thanks a lot for your help.
Solved! Go to Solution.
2020-09-23 06:40 AM
I think that's only if it's connected to something other than the main power supply at 3.3V. It would be odd otherwise.
2020-09-23 06:40 AM
I think that's only if it's connected to something other than the main power supply at 3.3V. It would be odd otherwise.
2020-09-23 08:33 AM
Totally agree! I haven't understood it that way: I thought it meant "when the internal regulator supply was not availabe"...
Thanks for enlightening me :)