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Associate
May 19, 2025
Question

Possible to keep VDD33USB as NC if USB feature not using In STM32H753ZIT6

  • May 19, 2025
  • 1 reply
  • 347 views

Can we  keep VDD33USB keep NC if USB feature not using In STM32H753ZIT6?

If kept NC what may go wrong? 

1 reply

AScha.3
Super User
May 19, 2025

NC is usually not the best idea , with any digital input pin;

see ds :

AScha3_0-1747636316782.png

So you could leave it to gnd. But why not set it to vdd ? So later, if you want USB, its there.

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Associate
May 19, 2025

thanks @AScha.3 , I agree on this, I fact i suggested to keep zero ohm and tie it with VDD( 3.3V). but issue is we are in final stage of Gerber generation ( keept this pin NC) . Now need strong reason to modify it now. 

also will you check on below snap?

abhilash72_0-1747637224639.png

if not used 0v to 3.6V. I not sure if 0V to 3.6V means not we can keep it NC.

adding link of application note 

*Getting started with STM32H723/733, STM32H725/735 and STM32H730 Value Line hardware development -

FAQ: Configuring the VDD50USB and VDD33USB pins on... - STMicroelectronics Community

AScha.3
Super User
May 19, 2025

From ds , 0...3v6 allowed, NC should be no problem for function of cpu.

But as always: a floating input (here power input) is not the "perfect" design idea.

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