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White Electronic Designs Corporation • (602) 437-1520 • www.wedc.com
White Electronic Designs
April 2005
Rev. 0
W3EG2128M64ETSR-JD3
ADVANCED
DDR SDRAM COMPONENT ELECTRICAL CHARACTERISTICS AND
RECOMMENDED AC OPERATING CONDITIONS (continued)
Notes 1-5, 7; notes appear following parameter tables; 0°C ≤ T
A
≤ +70°C; V
CC
= +2.5V ±0.2V, V
CCQ
= +2.5V ±0.2V
AC Characteristics 335 263/265
Parameter Symbol Min Max Min Max Units Notes
ACTIVE to READ or WRITE delay t
RCD
15 20 ns
PRECHARGE command period t
RP
15 20 ns
DQS read preamble t
RPRE
0.9 1.1 0.9 1.1 t
CK
19
DQS read postamble t
RPST
0.4 0.6 0.4 0.6 t
CK
ACTIVE bank a to ACTIVE bank b command t
RRD
12 15 ns
DQS write preamble t
WPRE
0.25 0.25 t
CK
DQS write preamble setup time t
WPRES
0 0 ns 10, 11
DQS write postamble t
WPST
0.4 0.4 t
CK
9
Write recovery time t
WR
15 15 ns
Internal WRITE to READ command delay t
WTR
11t
CK
Data valid output window NA t
QN
- t
DQSQ
t
QN
- t
DQSQ
ns 13
REFRESH to REFRESH command interval t
REFC
70.3 70.3 μs 12
Average periodic refresh interval t
REFI
7.8 7.8 μs 12
Terminating voltage delay to V
CC
t
VTD
00ns
Exit SELF REFRESH to non-READ command t
XSNR
126 127.5 ns
Exit SELF REFRESH to READ command t
XSRD
200 200 t
CK
