LSI Logic Confidential
AC Timing
18-21
Copyright © 2001, 2002 by LSI Logic Corporation. All rights reserved.
Note:
According to the specification, the HIGH/LOW period for
the clock signal should be a minimum of 40% of the cycle
time in SDR SDRAM, and in the range of 45–55% of the
cycle time in DDR SDRAM.
Figure 18.16 SDRAM Clock LOW and HIGH Period Definition
T
2
T
CYC
SDRAM_CLK
Clock High/Low Period In SDR Mode
Clock High/Low Period In DDR Mode
SDRAM_CLK
SDRAM_CLK
2.0 V
0.8 V
T
HIGH
T
LOW
T
1
Table 18.11 Clock Signals to SDRAM Timing
Symbol
Description
Min
Max
Units
T
CYC
Clock cycle period in SDR or DDR mode
81
148.5
MHz
T
HIGH
Clock HIGH period in SDR mode
0.4
0.6
T
CYC
T
LOW
Clock LOW period in SDR mode
0.4
0.6
T
CYC
T
1
Clock HIGH period in DDR mode
0.45
0.55
T
CYC
T
2
Clock LOW period in DDR mode
0.45
0.55
T
CYC
Содержание DMN-8600
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