EP4SE360F35I4 Datasheet, PDF (253/432 Pages) Altera Corporation – This section provides a complete overview of all features relating to the Stratix IV device family, which is the most architecturlly advanced

Chapter 7: External Memory Interfaces in Stratix IV Devices
Stratix IV External Memory Interface Features
7–29
Stratix IV External Memory Interface Features
Stratix IV devices are rich with features that allow robust high-performance external
memory interfacing. The ALTMEMPHY megafunction allows you to use these
external memory interface features and helps set up the physical interface (PHY) best
suited for your system. This section describes each Stratix IV device feature that is
used in external memory interfaces from the DQS phase-shift circuitry, DQS logic
block, leveling multiplexers, and dynamic OCT control block.
1 The ALTMEMPHY megafunction and the Altera memory controller MegaCore^®
functions can run at half the frequency of the I/O interface of the memory devices to
allow better timing management in high-speed memory interfaces. Stratix IV devices
have built-in registers in the IOE to convert data from full-rate (the I/O frequency) to
half-rate (the controller frequency) and vice versa. You can bypass these registers if
your memory controller is not running at half the rate of the I/O frequency. When
using the Altera memory controller MegaCore functions, the ALTMEMPHY
megafunction is instantiated for you.
f For more information about the ALTMEMPHY megafunction, refer to the External
Memory PHY Interface (ALTMEMPHY) (nonAFI) Megafunction User Guide.
DQS Phase-Shift Circuitry
Stratix IV phase-shift circuitry provides phase shift to the DQS/CQ and CQn pins on
read transactions when the DQS/CQ and CQn pins are acting as input clocks or
strobes to the FPGA. The DQS phase-shift circuitry consists of DLLs that are shared
between multiple DQS pins and the phase-offset module to further fine-tune the DQS
phase shift for different sides of the device.
February 2011 Altera Corporation
Stratix IV Device Handbook
Volume 1