Type: Answers, Errata

Area: EMIF, Intellectual Property



Cyclone III Speed Grade Support for Full-Rate DDR2 SDRAM Memory Specification

Description

The maximum clock rate for Cyclone III speed grades supporting full-rate DDR2 SDRAM on column I/Os are downgraded for version 9.1 and later. The maximum clock rate is downgraded because the Quartus II tool is unable to achieve push-button placement at the faster clock rates with DDR2 SDRAM high-performance controller II (HPC II).

table shows the downgraded specifications for the Quartus II software version 9.1.

Full-Rate DDR2 SDRAM Support for Cyclone III Devices

DDR2 SDRAM

Cyclone III

C6

167

C7

150

C8, I7, A7

150

Notes:You need 267-MHz memory component speed grade when using class I I/O standard and 333-MHz memory component speed grade when using class II I/O standard.You need 200-MHz memory component speed grade.
Memory Standard Device Speed Grade Maximum Full-Rate Clock Rate (MHz)
Column I/O (Single Chip Select)

This issue affects all designs that use full-rate DDR2 SDRAM with HPC II architecture and target the Cyclone III devices. If you are using DDR2 SDRAM with HPC architecture, you are not affected by this downgrade.

There is no design impact.

Workaround/Fix

To achieve higher clock rates, refer to the solution provided at http://www/support/kdb/solutions/rd05112010_783.html.

This issue will be fixed in a future version of the DDR2 Controller with ALTMEMPHY IP.