STM32H723 SDRAM clock

[elso]

Hi all,

I was reading through the documentation of the STM32H723 to find out what clock speed I can configure the FMC to run at using an external SDRAM. Looking at older posts and videos there is mentioned 100 MHz, but when I look at the newer/revised (revision 3) the max kernel fmc frequency has increased from 200 to 275 MHz:

Does this mean that now an external SDRAM can run at 137.5 MHz (kernel clock / 2) and not 100 MHz?

Best regards

 

Links I have compared to:

https://community.st.com/t5/stm32-mcus-products/stm32h7-maximum-sdram-frequency/td-p/336641#:~:text=Maximum%20SDRAM%20frequency%20is%20100%20MHz.&text=%2C%20section%208.5.,not%20be%20above%20200%20MHz.

 

https://www.youtube.com/watch?v=h28D4AaPSjg (14:00 min)

 

https://community.st.com/t5/stm32-mcus/how-to-set-up-the-fmc-peripheral-to-interface-with-the-sdram/ta-p/49457

 

[Tesla DeLorean]

SDRAM typically has a FMCCLK DIV2 and DIV3 option

[elso]

Hi, I found the solution on page 143 in the datasheet.

https://www.st.com/resource/en/datasheet/stm32h723zg.pdf (Only 550MHz MCUs)

 

[jiangfan]

DS_STM32H723x_Rev4, page 143 in the datasheet shows results for CRAM (FMC_SDCLK max is 137MHz:(

page 153 in the datasheet shows results for SDRAM (FMC_SDCLK max is 95MHz:(