FEDEVEL
Platform forum

tuandt , 04-18-2016, 08:58 PM

Hi,

I have a question relate to the Trace Length's rule for ddr1 track in IMX233. The rule said that


If possible, keep the DRAM DATA, DQM, STROBE, and CLOCK traces short enough so that a maximum of 30% of the edge appears on the trace. To put it in equation form: Trace Length <= (0.3 x Rise/Fall Time x 15 cm/ns)

The purpose of this rule to Minimizing Reflections of signals. So my questions are "How can i calculate the Rise/Fall Time? In the worst case, i can't calculate the value of Rise/Fall time, can i use the slew rate value or any other values and how to calculate?"

For more information, please refer to here


Thanks and have a nice day,
Tuan

robertferanec , 04-19-2016, 12:25 AM

I would say rise / fall time could be specified in datasheet of the CPU and memory.

tuandt , 04-21-2016, 08:56 PM

Hi,Robertferanec

Thank you for your suggestion