ppc460ex Applied Micro Circuits Corporation (AMCC), ppc460ex Datasheet - Page 91

• Manufacturer Part Number: ppc460ex
• Description: Powerpc 460ex Embedded Processor
• Manufacturer: Applied Micro Circuits Corporation (AMCC)

Revision 1.12 – July 17, 2008
Table 24. I/O Timing—DDR SDRAM Write Timing T
Notes:
1. T
2. Clock speed for the values in the table is 200MHz.
3. The time values in the table include 1/4 of a cycle at 200MHz.
4. To obtain adjusted T
DDR SDRAM Read Operation
The Read of the incoming Data from the SDRAM is done on the rising and falling edges of the differential DQS
signal. The Data must be centered to these edges for correct operation.
The PPC460EX can delay with very fine granularity the DQS through register programming.
DDR SDRAM MemClkOut0 and Read Clock Delay
In order to accommodate timing variations introduced by the system designs using this chip, the three-stage data
path shown below is used to eliminate metastability and allow data sampling to be adjusted for minimum latency.
The data is stored in the eight Flip Flops of the Stage 1, such that it can be transferred later within a 8x period.
AMCC Proprietary
MemData00:07, DM0
MemData08:15, DM1
MemData16:23, DM2
MemData24:31, DM3
MemData32:39, DM4
MemData40:47, DM5
MemData48:55, DM6
MemData56:63, DM7
ECC0:7, DM8
Preliminary Data Sheet
of the cycle time for the lower clock frequency (for example, T
SD
and T
Signal Names
HD
are measured under worst case conditions.
SD
and T
HD
values for lower clock frequencies, subtract 1.5 ns from the values in the table and add 1/4
Reference Signal
DQS0
DQS1
DQS2
DQS3
DQS4
DQS5
DQS6
DQS7
DQS8
SD
and T
SD
460EX – PPC460EX Embedded Processor
HD
− 1.5 + 0.25T
T
SD
0.96
0.97
0.98
0.98
0.98
0.97
0.96
0.96
0.96
(ns)
CYC
).
T
HD
0.995
0.990
0.980
0.980
0.980
0.983
0.982
0.985
0.980
(ns)
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