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AR# 21069

LogiCORE SPI-4.2 (POS-PHY L4) - Is there a minimum frequency requirement for RDClk?

Description

Is there a minimum frequency requirement for RDClk?

Solution

For Virtex-4 series devices, when an SPI4.2 Core is used in Dynamic Phase Alignment (DPA) mode, there is a minimum frequency requirement of 220 MHz. 

 

This requirement is needed because RDClk and RDat are source synchronous. RDClk sets the rate of RDat, which is crucial in performing data alignment. The edges on the RDat are needed to find the data-eye of incoming data (RDat). If RDat is running too slowly, a data transition might not be detected within 200-MHz period set by the ISERDES reference clock, and the DPA circuit will not be able to find the data-eye; therefore, the phase alignment cannot be completed.

AR# 21069
Date Created 09/04/2007
Last Updated 05/19/2014
Status Archive
Type General Article