W3EG7235S-JD3 Datasheet, PDF (9/12 Pages) White Electronic Designs Corporation – 256MB - 2x16Mx72 DDR SDRAM REGISTERED ECC, w/PLL

White Electronic Designs
W3EG7235S-JD3
PRELIMINARY
DDR SDRAM COMPONENT ELECTRICAL CHARACTERISTICS AND
RECOMMENDED AC OPERATING CONDITIONS (continued)
0°C ≤ TA ≤ +70°C; VCC = +2.5V ±0.2V, VCCQ = +2.5V ±0.2V
AC Characteristics
262/265
202
Parameter
Symbol
Min
Max
Min
Max
Units
ACTIVE to READ or WRITE delay
tRCD
15
20
ns
PRECHARGE command period
tRP
15
20
ns
DQS read preamble
tRPRE
0.9
1.1
0.9
1.1
tCK
DQS read postamble
tRPST
0.4
0.6
0.4
0.6
tCK
ACTIVE bank a to ACTIVE bank b command
tRRD
12
15
ns
DQS write preamble
tWPRE
0.25
0.25
tCK
DQS write preamble setup time
tWPRES
0
0
ns
DQS write postamble
tWPST
0.4
0.6
0.4
0.6
tCK
Write recovery time
tWR
15
15
ns
Internal WRITE to READ command delay
tWTR
1
1
tCK
Data valid output window
NA
tQH-tDQSQ
tQH-tDQSQ
ns
REFRESH to REFRESH command interval
tREFC
140.6
140.6
μs
Average periodic refresh interval
tREFI
15.6
15.6
μs
Terminating voltage delay to VCC
tVTD
0
0
ns
Exit SELF REFRESH to non-READ command
tXSNR
75
80
ns
Exit SELF REFRESH to READ command
tXSRD
200
200
tCK
Notes
19
10,11
9
13
12
12
November 2004
Rev. 2
9
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