USB trace impedance for STM32H725

VIR · ‎2025-03-13

I am laying out a USB for a STM32H725. I would like clarification on something out of the datasheet (DS13311).

Note 2 under table 118 states: No external termination series resistors are required on USB_DP (D+) and USB_DM(D-); the matching impedance is already included in the embedded driver.

I haven't found an example schematic with that specific MCU but found a similar one for STM32H7S7L8 (STM32H7S78-DK). In that schematic, the USB data lines are 90 ohms. They are going through a HS choke (ECMF2-40A100N6). The datasheet for that MCU has a similar note.

I'm not sure if that means I should make data traces 90ohms or not. Could someone clarify this for me please?

I will be running in FS mode using a USBLC6-4SC6 for ESD, if that matters.

FBL · ‎2025-03-18

Hi @VIR

Thank you for the question!

STM32H7S7L8 is different to STM32H725 for reference. You can refer to STM32H735 as they have same USB controller version.

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