AM5708: PCB routing guidelines

Blake Carpenter

Part Number: AM5708

Hi,

My customer is asking a quick question on what was the rational behind changing the routing guidelines spec from mm of skew in the AM335x to picoseconds in the AM570x.

He is just interested in they 'why' behind our decision.

Thanks!

over 9 years ago

0 -DK- over 9 years ago

TI__Mastermind 27890 points

Blake,

Are you referring to SPRS961A?

0 Blake Carpenter over 9 years ago in reply to -DK-

TI__Expert 7185 points

Yes, the datasheet. The customer clarifies:

Datasheet lists time for traces lengths in DDR routing section. Can they provide lengths instead? Or are they counting on the end user calculating the delays based on PCB stackup, trace type and dielectric constant?

Thanks!

0 sivak over 9 years ago in reply to Blake Carpenter

TI__Genius 9655 points

Blake

The length matching requirements were provided to ultimately accomplish tight skews across different net classes for DDR. Therefore, the delay requirements have been provided directly. Most layout tools have simple in built board delay calculator utilities to get this information.

What is the specific issue the customer has with the delay based requirements?

Regards, Siva

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AM5708: PCB routing guidelines