Running STM32H7 at 1.8V with USB High speed ULPI PHY USB3310

[caleb]

Hello all,

I'm building a system that I'd like to run at 1.8V with an STM32H7 and USB high speed PHY.

I have a few questions, so I'll just jump right in:

1) Will the STM32H7 core run at 400MHz when powered by VDD=1.8V? Some MCUs can't run as fast at lower voltages, so I wanted to make sure it'll run fine at 1.8V.

2) Internal (full-speed) phy: As long as I supply VDD33USB I assume it will work fine. However, is 3.3V required on VDD33USB if I'm using an external ULPI phy at 1.8V? The datasheet is not clear. It says in table 22 of STM32H570 datasheet: VDD33USB: USB USED 3.0-3.6V, USB not used: 0-3.6V. I suspect VDD33USB only powers the on-board full-speed PHY, but I'm not sure.

3) Has anybody tried the USB3310 PHY with STM32H devices at 1.8V? It would be great to know if I can expect this to work 🙂

Thank you so much,

-Caleb

[Tesla DeLorean]

>>1) Will the STM32H7 core run at 400MHz when powered by VDD=1.8V? Some MCUs can't run as fast at lower voltages, so I wanted to make sure it'll run fine at 1.8V.

Doesn't it run internally at 1.2V or lower?

[caleb]

That's what I thought, but just wanted to be doubly sure