STM32H7B0VBT6: Can I use USB HS at VDD=1.8V?

[JWeij.2]

Hello,

We are designing a board with an STM32H7B0VBT6 and USB3320 USB HS-transceiver. The MCU will run at VDD=1.8V.

In AN5307, p. 11 it is written:

"On some packages neither the VDD33USB pin, nor the VDD50USB pin are available, it is the VDD pin which supplies the VDD33USB through an internal connection. In this case, VDD is constrained by VDD33USB and must range between 3.0 V and 3.6 V."

The package that we use does not have these pins. However, I expect that the statement above only applies when using the internal FS transceiver, which we are not: We are using an external HS-transceiver through ULPI.

Is it correct to assume then that in our situation we can use VDD=1.8V?

[STOne-32 · Accepted solution]

Dear @JWeij.2​ ,

Your assumptions are correct ! The VDD33 rail is only when embedded full speed PHY is used. In case you use an external ULPI PHY either for Full speed or High speed USB connection, you can can operate with VDD of 1.8Volts and using USB3320 transceiver.

Cheers,