i.MX6 SDIO IO voltage

[Kazuma_Sasaki]

Current our design only 1.8V supply to NVCC_SDx pin.

it means that we do not change IO voltage response to access speed changing.

Is it okay for SD host controller in i.MX6?

Because, SDIO specification v3.0 mentioned as below.

1.2.3 Embedded SDIO Device Features

・Supply Voltage rage：2.7-3.6V or 1.7-1.95V

Best Regards,

Kazuma Sasaki.

[igorpadykov]

Hi Kazuma

according to sect.3.9.6 Summary of Bus Speed Mode SD 3.0 specification:
DS - Default speed up to 25MHz 3.3V signaling,

So switching to 1.8V should be performed from 3.3V as stated in

sect.4.2.4 Bus Signal Voltage Switch Sequence, sect.4.2.4.2  Timing to Switch Signal Voltage

Simplified Specifications - SD Association 

Example of switching NVCC_SD3 can be found on p.6 SCH-27142 i.MX6Q Sabre AI schematic

SABRE|Automotive-Infotainment|i.MX6|NXP 

Best regards
igor
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[Kazuma_Sasaki]

Hi Igor,

I appreciate your support.

I've checked your pointed document.( Physical Layer Simplified Specification v6.0 )

Did you mean i.MX6 can not work start from 1.8V?
We must start from 3.3V. then, switching to 1.8V based on sect.4.2.4 Bus Signal Voltage Switch Sequence.

is it right?

Best Regards,

Kazuma Sasaki.

[igorpadykov]

Hi Kazuma

yes it is right.

Best regards
igor

[Kazuma_Sasaki]

Hi Igor,

Let me confirm once again.

You have commented i.MX6 is working Default Speed with 1.8V at following URL.

If Default Speed is working with 1.8V, I suppose i.MX6 is able to work without voltage switching 3.3V to 1.8V.

Really do we need the voltage switch 3.3V to 1.8V?

https://community.nxp.com/message/810830?commentID=810830#comment-810830 

Best Regard,

Kazuma Sasaki.

[igorpadykov · Accepted solution]

Hi Kazuma

according to original question on that thread:

"Our customer don't need SD voltage switching and UHS.." -

so for card not following sdio specs.

If your question is about card which should follow sdio specification requirements

then switching is needed.

Best regards
igor