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Rev. D
|
Page 26 of 56
|
November 2008
ADSP-21367/ADSP-21368/ADSP-21369
SDRAM Interface Timing (166 MHz SDCLK)
The 166 MHz access speed is for a single processor. When mul-
tiple ADSP-21368 processors are connected in a shared memory
system, the access speed is 100 MHz.
The processor needs to be programmed in t
SDCLK
= 2.5
×
t
CCLK
mode when operated at 350 MHz.
Table 23. SDRAM Interface Timing
1
350 MHz
All Other Speed Grades
Unit
Parameter
Min
Max
Min
Max
Unit
Timing Requirement
s
t
SSDAT
DATA Setup Before SDCLK
500
500
ps
t
HSDAT
DATA Hold After SDCLK
1.23
1.23
ns
Switching Characteristic
s
t
SDCLK
SDCLK Period
7.14
6.0
ns
t
SDCLKH
SDCLK Width High
3
2.6
ns
t
SDCLKL
SDCLK Width Low
3
2.6
ns
t
DCAD
Command, ADDR, Data Delay After SDCLK
2
4.8
4.8
ns
t
HCAD
Command, ADDR, Data Hold After SDCLK
2
1.2
1.2
ns
t
DSDAT
Data Disable After SDCLK
5.3
5.3
ns
t
ENSDAT
Data Enable After SDCLK
1.3
1.3
ns
1
For f
CCLK
= 400 MHz (SDCLK ratio = 1:2.5).
2
Command pins include: SDCAS, SDRAS, SDWE, MSx, SDA10, SDCKE.
Figure 16. SDRAM Interface Timing
t
HCAD
t
HCAD
t
D
S
DAT
t
SS
DAT
t
DCAD
t
EN
S
DAT
t
H
S
DAT
t
S
DCLKL
t
S
DCLKH
t
S
DCLK
S
DCLK
DATA (IN)
DATA(OUT)
CMND ADDR
(OUT)
t
DCAD