
Altera Corporation
3–3
January 2008
Stratix II Device Handbook, Volume 2
External Memory Interfaces in Stratix II and Stratix II GX Devices
Table 3–1 summarizes the maximum clock rate Stratix II and Stratix II GX
devices can support with external memory devices.
This chapter describes the hardware features in Stratix II and Stratix II GX
devices that facilitate the high-speed memory interfacing for each DDR
memory standard. This chapter focuses primarily on the DLL-based
implementation. The PLL-based implementation is described in
application notes. It then lists the Stratix II and Stratix II GX feature
enhancements from Stratix devices and briefly explains how each
memory standard uses the Stratix II and Stratix II GX features.
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Table 3–1. Stratix II and Stratix II GX Maximum Clock Rate Support for External Memory Interfaces
Memory Standards
–3 Speed Grade (MHz)
–4 Speed Grade (MHz)
–5 Speed Grade (MHz)
DLL-Based
PLL-Based
DLL-Based PLL-Based
DLL-Based
PLL-Based
333
200
267
167
233
167
200
150
200
133
200
100
RLDRAM II
300
200
175
200
175
QDRII SRAM
300
200
250
167
250
167
QDRII+ SRAM
300
250
250
(1)
Memory interface timing specifications are dependent on the memory, board, physical interface, and core logic.
Refer to each memory interface application note for more details on how each specification was generated.
(2)
The respective Altera MegaCore function and the EP2S60F1020C3 timing information featured in the Quartus II
software version 6.0 was used to define these clock rates.
(3)
This applies for interfaces with both modules and components.
(4)
You must underclock a 300-MHz RLDRAM II device to achieve this clock rate.
(5)
267 MHz or below, continue to use the static resynchronization data path currently supported by the released
version of the MegaCore function.
(6)
The lowest frequency at which a QDRII+ SRAM device can operate is 238 MHz. Therefore, the PLL-based
implementation does not support the QDRII+ SRAM interface.