SDHC layout recommendations

[fernandoalcaide]

Dear,

I am designing  Board  with Vybrid VF6 and I have doubt about SDHC layout recommentaions appears in paragraph 3.3.2.3 SD Card interface requirements of ref. doc. VYBRIDHDUG_HW_UserGuide.

In this paragrap appears:

1. The clock trace should be longer than the longest trace in the Data /Command group (+5mils).

Is 5mils minimun distance or  maximum  ?

2. SD card interface layout requirements are very similar to those for the DDR one (see Section 3.5,

“DDR routing rules”).

But in this section appears DDR3 recommnedations?

I need to kown routing recomentadion to SDHC.

Can somebody help me?

Thank you in advance.

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[karina_valencia]

jiri-b36968​ can you comment please?

[jiri-b36968]

Hello Fernando,

yes, reference design uses DRAM memory type DDR3 (DDR is imprecise expression).

SDHC runs up to 50MHz.

- try to make lines short

- match all lines length.

- Add 5 mils to clk.

- try to keep lines on one layer.

- Ensure correct return path (continuous ground under lines)

- consider ESD protection if SD card is accessible to users.

/Jiri

[fernandoalcaide]

Thank you

[timesyssupport]

Hi Karina valencia Aguilar,

                                             Can the NXP Vybrid Hardware team please comment on this?

Thanks

Timesys Support