STM32U5xx vs. STM32H5xx - USB?

[tjaekel]

I have a board with STMU5A5, as LQFP64, and I am thinking to substitute (just) the MCU with a STM32H5xx one (also as LQFP64 package, because it is faster (250MHz instead of 160MHz)).
After checking the pinout and datasheet - I came to one conclusion and one question (just to confirm).

Conclusion:

I have STM32U5 as LQFP64 with SMPS option (hard to order the LDO version). The STM32H5 has also a LQFP64 package:
BUT: just as LDO version, not as SMPS!
SMPS is just available from LQFP100 upwards. "rrrrr" (so, I cannot change, without to modify PCB)

Question (please confirm):

My STM32U5 LQFP64 has an USBVDD pin. But the STM32H5 LQFP64 does not (just all as VDD).

Does it mean?:
"USB (via the internal FS PHY) is not possible on a STM32H5 LQFP64?" (because no power to USB PHY)

Or is there an internal bonding from VDD to VDDUSB so that USB would work?
But it remains another conclusion if so: VDDUSB needs at least 3.0V. So, I cannot run STM32H5 with 1V8.

Is my assumption correct?:
a) no USB on STM32H5 LQFP64?
b) and even it is: no way to run STM32H5 (with USB) on 1V8?

Thank you.

[STOne-32]

Dear @tjaekel ,

Thank you for the question - clear and direct to the point « crystal clear ». All of your analysis is correct.  In fact, the STM32H5 series is built around the idea to upgrade our customers applications from STM32F4 series ( High performance MCUs) using state of the art Security Core such as Cortex-M33 while stretching the MCU market entry level High Performance MCU up to 250MHz with all modern peripherals. This is not the case for U5 which is in ULP market and keeping each uA/MHz and nA at an optimized cost and running consumer applications / that means by default 1.8V and SMPS by default .

Having USB while VDD at 1.8V for H5 series you need to start with LQFP100 package option and not offer for less pin count else going to very compact WLSP package .

https://www.st.com/resource/en/application_note/an5711-getting-started-with-stm32h5-mcu-hardware-development-stmicroelectronics.pdf

Pleased to help you.

STOne-32

[tjaekel]

Thank you for confirming. All makes sense.
Just: does it mean on LQFP64 package the VDDUSB is running from VDD (with 3V3 needed)?
Or is the USB FS PHY not powered in the smaller packages? (so that USB works only on larger packages)

[STOne-32]

Hi @tjaekel ,

We need 3V3 volts and  VDDUSB rail is bonded to VDD at package level.

Ciao

STOne-32.

[tjaekel · Accepted solution]

Great, thank you.
So, USB is available on all packages even if package does not provide VDDUSB.
Just to run the MCU with 3V3. All fine. (I will give it a try).