W3EG7236S-D3
White Electronic Designs
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
tRCD
Min
20
Max
Min
20
Max
Units
ns
Notes
ACTIVE to READ or WRITE delay
PRECHARGE command period
DQS read preamble
tRP
20
20
ns
tRPRE
tRPST
tRRD
0.9
0.4
15
1.1
0.6
0.9
0.4
15
1.1
0.6
tCK
tCK
ns
19
DQS read postamble
ACTIVE bank a to ACTIVE bank b command
DQS write preamble
tWPRE
tWPRES
tWPST
tWR
0.25
0
0.25
0
tCK
ns
DQS write preamble setup time
DQS write postamble
10,11
9
0.4
15
0.6
0.4
15
0.6
tCK
ns
Write recovery time
Internal WRITE to READ command delay
Data valid output window
tWTR
1
1
tCK
ns
NA
tQH-tDQSQ
tQH-tDQSQ
13
12
12
REFRESH to REFRESH command interval
Average periodic refresh interval
Terminating voltage delay to VCC
Exit SELF REFRESH to non-READ command
Exit SELF REFRESH to READ command
tREFC
tREFI
70.3
7.8
70.3
7.8
μs
μs
tVTD
0
0
ns
tXSNR
tXSRD
75
80
ns
200
200
tCK
November 2004
Rev. 1
9
White Electronic Designs Corporation • (602) 437-1520 • www.wedc.com
WEDC [ WHITE ELECTRONIC DESIGNS CORPORATION ]
