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Altera Corporation
3–11
June 2006
Stratix Device Handbook, Volume 2
External Memory Interfaces in Stratix & Stratix GX Devices
Stratix and Stratix GX devices support the data strobe or read clock signal
(DQS) used in DDR SDRAM, and RLDRAM II devices. DQS signals are
associated with a group of data (DQ) pins.
Stratix and Stratix GX devices contain dedicated circuitry to shift the
incoming DQS signals by 0°, 72°, and 90°. The DQS phase-shift circuitry
uses a frequency reference to dynamically generate control signals for the
delay chains in each of the DQS pins, allowing it to compensate for
process, voltage, and temperature (PVT) variations. The dedicated
circuitry also creates consistent margins that meet your data sampling
window requirements.
f
Refer to the DC & Switching Characteristics chapter in volume 1 of the
Stratix Device Handbook for frequency limits regarding the 72 and 90°
phase shift for DQS.
In addition to the DQS dedicated phase-shift circuitry, every I/O element
(IOE) in Stratix and Stratix GX devices contains six registers and one latch
to achieve DDR operation. There is also a programmable delay chain in
the IOE that can help reduce contention when interfacing with ZBT
SRAM devices.
DDR Memory Interface Pins
Stratix and Stratix GX devices use data (DQ), data strobe (DQS), and clock
pins to interface with DDR SDRAM and RLDRAM II devices. This section
explains the pins used in the DDR SDRAM and RLDRAM II interfaces.
LVTTL
200
167
(1)
These maximum clock rates apply if the Stratix device uses DQS phase-shift circuitry to interface with DDR
SDRAM. DQS phase-shift circuitry is only available on the top and bottom I/O banks (I/O banks 3, 4, 7, and 8).
(2)
For more information on DDR SDRAM, see AN 342: Interfacing DDR SDRAM with Stratix & Stratix GX Devices.
(3)
DDR SDRAM is supported on the side banks (I/O banks 1, 2, 5, and 6) with no dedicated DQS phase-shift circuitry.
The read DQS signal is ignored in this mode.
(4)
For more information on QDR or QDRII SRAM, see AN 349: QDR SRAM Controller Reference Design for Stratix &
Stratix GX Devices.
(5)
For more information on ZBT SRAM, see AN 329: ZBT SRAM Controller Reference Design for Stratix and Stratix GX
Devices.
Table 3–2. External RAM Support in Stratix EP1S60 & EP1S80
(Part 2 of 2)
DDR Memory Type
I/O Standard
Maximum Clock Rate (MHz)
-5 Speed Grade
-6 Speed Grade
-7 Speed Grade