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Connecting SD CARD to STM32H743 without level translator

Mosi
Associate II

I was looking at the schematic of a ST STM32H743I-EVAL board and noticed it uses a voltage level translator to connect a SD CARD to STM32H743 and used a separate LDO to produce 2.9V for the SD side.

The custom hardware I'm designing has a 176 pin STM32H743II supplied with 3.3V only. Now I couldn't find more information on this but is it really necessary to use a voltage translator at all?

I would rather not use a translator with that BGA package or any other unnecessary IC for that matter.

1 ACCEPTED SOLUTION

Accepted Solutions
Mike_ST
ST Employee

Hello,

we have the STM32H747 discovery board that features an sdcard interface with only an ESD protection, and no level shifter,

please have a look:

H747 Disco

Shouldn't be different for the STM32H743.

In any case, please check the SDcard specifications for what is needed depending of what kind of card you want  to support:

SD overview 

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6 REPLIES 6
EZHON.1
ST Employee

when inserts SD card, there is a voltage drop for 3.3V rail. it should be better to add a dedicated LDO for SD card.

Thanks. That actually makes sense. Plus I'm gonna need an ESD protection so I figured it is better to use voltage level translator with ESD protection and a QFN package like TXS02612  and a LDO. 

Mike_ST
ST Employee

Hello,

we have the STM32H747 discovery board that features an sdcard interface with only an ESD protection, and no level shifter,

please have a look:

H747 Disco

Shouldn't be different for the STM32H743.

In any case, please check the SDcard specifications for what is needed depending of what kind of card you want  to support:

SD overview 

EZHON.1
ST Employee

STM32H743I-EVAL supports SDIO3.0 interface microSD™ card while STM32H747I-DISCO supports SDIO2.0 interfacemicroSD™ card. They are different SDcard specifications.

You don't need the transceiver. Only used for high speed ultra modes. Should be able to clock 50+ MHz at usual voltages without them.

https://community.st.com/t5/stm32-mcus-products/stm32h753vit6-sd-card-sdr104/m-p/614777

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Interesting. Does it have anything to do with the voltage translator?