T
T
T
S
S
S
3
3
3
2
2
2
M
M
M
L
L
L
D
D
D
6
6
6
4
4
4
V
V
V
3
3
3
F
F
F
5
5
5
184PIN DDR333 Unbuffered DIMM
256MB With 32Mx8 CL2.5
AC TIMING PARAMETERS & SPECIFICATIONS
(These AC characteristics were tested on the Component)
Parameter Symbol Min Max Unit Note
Row cycle time tRC 60 ns
Refresh row cycle time tRFC 72 ns
Row active time tRAS 42 70K ns
/RAS to /CAS delay tRCD 18 ns
Row active to Row active delay tRP 18 ns
Row active to Row active delay tRRD 12 ns
Write recovery time tWR 15 ns
Last data in to Read command tWTR 1 tCK
Col. Address to Col. Address delay tCCD 1 tCK
Clock cycle time tCK 6 ns 4
Clock high level width tCH 0.45 0.55 tCK
Clock low level width tCL 0.45 0.55 tCK
DQS-out access time from CK /CK tDQSCK -0.6 0.6 ns
Output data access time from CK /CK tAC -0.7 0.7 ns
Data strobe edge to output data edge tDQSQ 0.45 ns 4
Read Preamble tRPRE 0.9 1.1 tCK
Read Postamble tRPST 0.4 0.6 tCK
CK to valid DQS-in tDQSS 0.75 1.25 tCK
DQS-in setup time tWPRES 0 ns 2
DQS-in hold time tWPREH 0.25 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
DQS-in high level width tDQSH 0.35 tCK
DQS-in low level width tDQSL 0.35 tCK
DQS-in cycle time tDSC 0.9 1.1 tCK
Address and Control input setup time tIS 0.75 ns
Address and Control input hold time tIH 0.75 ns
Data-out high-impedance time from CK, /CK tHZ -0.7 0.7 ns
Data-out low-impedance time from CK, /CK tLZ -0.7 0.7 ns
Mode register set cycle time tMRD 12 ns
DQ & DM setup time to DQS tDS 0.45 ns
DQ & DM hold time to DQS tDH 0.45 ns
DQ & DM input pulse width tDIPW 1.75 ns
Exit self refresh to non-read command tXSNR 75 ns 4
Exit self refresh to read command tXSRD 200 tCK
Refresh interval time tREF 7.8 us 1
Clock half period tHP
tCLmin or
tCHmin
ns
DQS write postamble time
tWPST tRCD or tRAS
min
tCK 3
1. Maximum burst refresh of 8
2. The specific requirement is that DQS be valid (High or Low) on or before this CK edge. The case shown (DQS
going from High_Z to logic Low) applies when no writes were previously in progress on the bus. If a previous
write was in progress, DQS could be High at this time, depending on tDQSS.
3. The Maximum limit for this parameter is not a device limit. The device will operate with a great value for this
parameter, but system performance (bus turnaround) will degrade accordingly.
Note:
4.
For registered DIMMs, tCL and tCH are >= 45% of the period including both the half period jitter (tJIT(HP) ) of
the PLL and the half period jitter due to crosstalk (tJIT(crosstalk)) on the DIMM.
Transcend Information Inc.
8