AM3517 MMC2_CLKIN QUESTION

Dennis Nguyen

Other Parts Discussed in Thread: AM3517

Hi,

We are looking at EVM3517 (LogicPD) and TI Wiki page http://processors.wiki.ti.com/index.php/SD-MMC_Usage_Notes_on_AM35x. From the notes "MMC2, with its direction control signals and CLKIN, is best suited for designs which need relaxed design constraints (large boards or long traces)".

My question is how long of the trace, between the wifi chip and the AM3517 processor, for the hardware board needs to consider the present of SN74AVCA406L voltage-translator tranceiver for external MCC2_CLKIN back to the processor?

In the AM3517 EVM, the Soc has the processor right next to the LBEH19XMMC WiFi chip. WinCE BSP SDIO driver set MMCSDIO2ADPCLKISEL=1 to have the processor internal loop back. This EVM works fine. If my custom board has the processor and the WiFi chip about 6" apart, do I really need to have SN74AVCA406L? We just want to clarify how long is "long"?

Thanks,

Dennis

over 14 years ago

0 Jeff Culverhouse over 14 years ago

TI__Genius 9190 points

Hello Dennis,

The loop back using the transceiver is suggested to keep the timing correct since your board is at 6" which is a pretty large distance I would definately use the transciever. It might work without, but I would then be worried about corner case timing failure.

0 Dennis Nguyen over 14 years ago in reply to Jeff Culverhouse

Expert 1690 points

Thanks, Jeff. I forwarded your information to our design engineers. Our hardware should handle the traffic efficiently and the tranceiver is available for this purpose.

You have a great day,

Dennis

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AM3517 MMC2_CLKIN QUESTION