Which clock to use for tDISKEW calculation

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Which clock to use for tDISKEW calculation

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creinhold
Contributor I

I am investigating an interface between the MPC8308  and a  532MT/s DDR2 RAM and I would like to calculate the the total amount of allowed skew from MDQS to a corresponding MDQ signals tDISKEW.

The document MPC8308 PowerQUICC II Pro, Processor Hardware Specification
Document Number: MPC8308EC, Rev. 4, 12/2014

gives on page 11 a formular to calculate tDISKEW from a clock periode and the controller skew (see attached screenshot). However, it is not mentioned whick clock periode shall be used. Is it the MCK clock periode which in my case would be T=1/133MHz giving a tDISKEW of approx. +/-1ns?

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Bulat
NXP Employee
NXP Employee

You are right, it means MCK clock period. tDISKEW is -1ns (min) to +1ns (max).

Regards,

Bulat

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