How to run SDMMC1 with 1.8V

[HHako.1]

Hello Dear all,

I want to run my STM32L452ret6 with 1.8V and use SDMMC1 module.

I can use SDMMC1 with 3.3V and 50k pull ups without problems, but when I run the MCU with 1.8V and use TXB0104RGY for shifting voltaghe to 3.3 it dose not work as expected. 

Which component to use for shifting SDMMC1 signals from 1.8V to 3.3V?

Can I set pull up resistors with 50k valu to 3.3V but run 1.8V from mcu ?

Regards,

Hakob

[AScha.3]

Hi,

>Can I set pull up resistors with 50k valu to 3.3V but run 1.8V from mcu ?

NO. (cpu P-P outputs cannot be driven > VDD (+0,3V or so) )

+

Maybe your TXB0104RGY is too slow...try LSF0108 , 

https://www.ti.com/lit/ds/symlink/lsf0108.pdf

https://www.mouser.de/ProductDetail/Texas-Instruments/LSF0108PWR?qs=MJut%2BdqOEgjIYRbmgD64ig%3D%3D

+

keep connections short - i had no luck with 100mm from cpu to sd-card, 40mm working fine.

 

[HHako.1]

Dear AScha.3,

Thank you for your response.  

Do you use pull ups with LSF0108?

[AScha.3]

Well i dont use it . :)

But pullups are a good idea - the sd-card expecting this (all lines pulled up) on insertion/start, at 3,3V (min. 2,7V).

And tell, whats it doing with LSF0108 (at least TI states, it should work) ->