Problem with high speed in a custom board with STM32H735IGT6

JVale.2 · ‎2023-10-11

Hi.

I am Jose Manuel. We have developed a custom board where the MCU is STM32H735IGT6, the external SRAM is APS12808L-3OBMX-BA and the external flash is W25Q128JVEIM.

The problem is that we want to work with 100 MHz, but it does not work, it just work up to 60 MHz.

We have developed a board with four levels, the same lenghts in the route and the same vias. Below, attached the interface between the SRAM and MCU. Could you please tell us what steps we have not done? Whats the recommendation to follow?

Thanks you and Best regards,

José Manuel

Piranha · ‎2023-11-28

the equal length of the signals are very important = > resistance matching(here should be 50ohm).

Not resistance, but impedance. Those things are not the same!