
W3EG7264S-AD4
-BD4
7
White Electronic Designs Corporation (602) 437-1520 www.whiteedc.com
White Electronic Designs
January 2005
Rev. 3
PRELIMINARY
DDR SDRAM COMPONENT ELECTRICAL CHARACTERISTICS AND RECOMMENDED AC
OPERATING CONDITIONS
AC CHARACTERISTICS
335
262
265
202
PARAMETER
SYMBOL MIN
MAX
MIN
MAX
MIN
MAX
MIN
MAX
UNITS NOTES
Access window of DQs from CK/CK#
tAC
-0.7
+0.7
+0.75
-0.75
+0.75
-0.75
+0.75
-0.75
ns
CK high-level width
tCH
0.45
0.55
0.45
0.55
0.45
0.55
0.45
0.55
tCK
25
CK low-level width
tCL
0.45
0.55
0.45
0.55
0.45
0.55
0.45
0.55
tCK
25
Clock cycle time
CL = 2.5
tCK (2.5)
7.6
13
10
13
10
13
10
13
ns
37, 42
CL = 2
tCK (2)
7.5
13
7.5
13
7.5
13
7.5
13
ns
41
DQ and DM input hold time relative to DQS
tDH
0.45
ns
22, 26
DQ and DM input setup time relative to DQS
tDS
0.45
ns
22, 26
DQ and DM input pulse width (for each input)
tDIPW
1.75
ns
26
Access window of DQS from CK/CK#
tDQSCK
-0.60
+0.60
+0.8
ns
DQS input high pulse width
tDQSH
0.35
tCK
DQS input low pulse width
tDQSL
0.35
tCK
DQS-DQ skew, DQS to last DQ valid, per group, per
access
tDQSQ
0.45
0.6
ns
22
Write command to rst DQS latching transition
tDQSS
0.75
1.25
0.75
1.25
0.75
1.25
0.75
1.25
tCK
DQS falling edge to CK rising - setup time
tDSS
0.2
tCK
DQS falling edge from CK rising - hold time
tDSH
0.2
tCK
Half clock period
tHP
tCH,tCL
ns
29
Data-out high-impedance window from CK/CK#
tHZ
+0.70
+0.8
ns
16, 36
Data-out low-impedance window from CK/CK#
tLZ
-0.70
-0.8
ns
16, 36
Address and control input hold time (1 V/ns)
tIHF
0.75
ns
12
ns
12
ns
12
ns
12
Address and control input setup time (1 V/ns)
tISF
0.75
1.1
ns
12
Address and control input hold time (0.5 V/ns)
tIHS
0.80
1.1
ns
12
Address and control input setup time (0.5 V/ns)
tISS
0.80
1.1
ns
12
Address and Control input pulse width (for each input)
tIPW
2.2
ns
LOAD MODE REGISTER command cycle time
tMRD
12
16
ns
DQ-DQS hold, DQS to rst DQ to go non-valid, per
access
tQH
tHP - tQHS
ns
22
Data hold skew factor
tQHS
0.55
1
ns
ACTIVE to PRECHARGE command
tRAS
42
70,000
40
120,000
40
120,000
40
120,000
ns
30
ACTIVE to READ with Auto precharge command
tRAP
15
20
ns
ACTIVE to ACTIVE/AUTO REFRESH command
period
tRC
60
70
ns
AUTO REFRESH command period
tRFC
72
75
ns
40
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
0.9
1.1
0.9
1.1
tCK
DQS read postamble
tRPST
0.4
0.6
0.4
0.6
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
tCK
DQS write preamble setup time
tWPRES
0000
ns
17, 19