Type: Answers, Errata

Area: EMIF, Intellectual Property



Prefitter Not Instantiating io_clock_divider and DQSLB when DQSLB has No Associated EMIF Pins

Description

This problem affects QDR II, and RLDRAM II products.

For designs with x18 or x36 DQ groups, it is possible that the data pins do not require I/Os in all the DQ groups. When this happens, the prefitter does not duplicate the I/O clock divider atom into the DQ groups that do not contain an I/O. The I/O clock divider atoms in a DQ group must be connected in cascade; when an I/O clock divider atom is not present in one of the DQ groups, a hardware failure may occur.

Workaround/Fix

After duplication, if the number of I/O clock dividers is less than the number of DQSLBs, the prefitter inserts the missing I/O clock divider atoms. These atoms do not have a fanout. The prefitter clusters the I/O clock divider atoms in the DQ group by traversing their fan-ins (DQS delay chain).

This issue has been fixed.