USB PHY internal vs external?

[Ricko]

Hi,

in CubeMX for the STM32F750V8T6, there is an option for External PHY or Internal PHY (see screenshot below).

What is the point of using external PHY? It seems to just add cost and complexity. Is it perhaps considerably faster?

Thank you

[gbm]

Only the newest and most powerful models of H7 and U5 have built-in HS PHY. With older ones, you may use the on-chip FS-only PHY or external HS PHY (supporting HS and FS).

[TDK]

An external HS PHY (480 MHz) will be considerably faster than the internal FS PHY (12 MHz). That is the primary reason.

[Tesla DeLorean · Accepted solution]

It used to have to do with process technologies, and specific requirements of the pin-drivers to create a compilant bus at 480 Mbps

In a general purpose MCU there's the weight of supporting this vs the utility of it for everyone else who isn't

The F723 has a HS PHY built in, and thus it's choice for the ST-LINK/V3.

This obviously pushes part choices and compromises back into your court, and how you might chose to partition your design.