EP1S40B956C5 Altera, EP1S40B956C5 Datasheet - Page 415

• Manufacturer Part Number: EP1S40B956C5
• Description: IC STRATIX FPGA 40K LE 956-BGA
• Manufacturer: Altera
• Series: Stratix®r

Specifications of EP1S40B956C5

• Number Of Logic Elements/cells: 41250
• Number Of Labs/clbs: 4125
• Total Ram Bits: 3423744
• Number Of I /o: 683
• Voltage - Supply: 1.425 V ~ 1.575 V
• Mounting Type: Surface Mount
• Operating Temperature: 0°C ~ 85°C
• Package / Case: 956-BGA
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Number Of Gates: -

Altera Corporation
June 2006
f
Figure 3–9. Simplified Diagram of the DQS Phase-Shift Circuitry
The input reference clock goes into the DLL to a chain of delay elements.
The phase comparator compares the signal coming out of the end of the
delay element chain to the input reference clock. The phase comparator
then issues the upndn signal to the up/down counter. This signal
increments or decrements a six-bit delay setting (control signals to DQS
pins) that increases or decreases the delay through the delay element
chain to bring the input reference clock and the signals coming out of the
delay element chain in phase.
The shifted DQS signal then goes to the DQS bus to clock the IOE input
registers of the DQ pins. It cannot go into the logic array for other
purposes.
For external memory interfaces that use a bidirectional read strobe like
DDR SDRAM, the DQS signal is low before going to or coming from a
high-impedance state (see
is low just after a high-impedance state is called the preamble and the
state where DQS is low just before it returns to high-impedance state is
called the postamble. There are preamble and postamble specifications
for both read and write operations in DDR SDRAM. To ensure data is not
lost when there is noise on the DQS line at the end of a read postamble
time, you need to add soft postamble circuitry to disable the clocks at the
DQ IOE registers.
For more information, the DQS Postamble soft logic is described in
AN 342: Interfacing DDR SDRAM with Stratix & Stratix GX Devices. The
Altera DDR SDRAM controller MegaCore
open-source code.
Reference
Clock
Input
External Memory Interfaces in Stratix & Stratix GX Devices
Comparator
Phase
Figure 3–1 on page
Delay Chains
Stratix Device Handbook, Volume 2
Up/Down
Counter
®
generates this logic as
3–3). The state where DQS
6
Control Signals
to DQS Pins
3–19