i.MX RT 106x SD card voltage

[nickwallis]

I'm confused about the NXP i.MX RT 106x reference design SD card voltages

The reference schematics have the option to power the relevant MCU bank from either 3.3V or 1.8V

But the SD card connector itself can only be powered from +3.3V

... and therefore the card will always output 3.3V levels, and have input thresholds appropriate for 3.3V.

So, how does this even work when configured for 1.8V operation?

regards

-Nick

[andrew58210]

How is this an error?  SDcards always run off 3.3V even when you change the I/O voltage to 1.8V.

[nickwallis]

Hi Felipe,

Thank you for your reply.

So, this looks like an error in the MIMXRT1060-EVK design? And the solution, I think, is that the SD card connector J39 should be powered from NVCC_SD (clearly this will also impact the power switch U37).

The card detect (SD_CD_SW) is OK because it is a switch to GND rather than a driven signal, and it connects to an MCU bank that is powered from +3.3V.

Do you agree?

regards

-Nick

[FelipeGarcia]

Yes, I totally agree with you.

Regards,

Felipe

[FelipeGarcia]

Hi Nick,

Unfortunately, MIMXRT1060-EVK does not support SD card voltage switch due to the limitation in SD card connector that you pointed out.

Sorry for the inconvenience this may cause you.

Best regards,

Felipe