256Mb: x4, x8, x16 SDRAM
Electrical Specifications – AC Operating Conditions
measured from VIL,max and VIH,min and no longer from the 1.5V midpoint. CLK should al-
ways be 1.5V referenced to crossover. Refer to Micron technical note TN-48-09.
6. Not applicable for Revision D.
7. tAC for -75/-7E at CL = 3 with no load is 4.6ns and is guaranteed by design.
8. The clock frequency must remain constant (stable clock is defined as a signal cycling
within timing constraints specified for the clock pin) during access or precharge states
(READ, WRITE, including tWR, and PRECHARGE commands). CKE may be used to reduce
the data rate.
9. tHZ defines the time at which the output achieves the open circuit condition; it is not a
reference to VOH or VOL. The last valid data element will meet tOH before going High-Z.
10. Parameter guaranteed by design.
11. DRAM devices should be evenly addressed when being accessed. Disproportionate ac-
cesses to a particular row address may result in reduction of the product lifetime.
12. AC characteristics assume tT = 1ns.
13. Auto precharge mode only. The precharge timing budget (tRP) begins at 6ns for -6A, 7ns
for -7E, and 7.5ns for -75 after the first clock delay, after the last WRITE is executed.
14. Precharge mode only.
15. CLK must be toggled a minimum of two times during this period.
16. Required clocks are specified by JEDEC functionality and are not dependent on any tim-
ing parameter.
17. Timing is specified by tCKS. Clock(s) specified as a reference only at minimum cycle rate.
18. Timing is specified by tWR plus tRP. Clock(s) specified as a reference only at minimum cy-
cle rate.
19. Based on tCK = 7.5ns for -75 and -7E, 6ns for -6A.
20. Timing is specified by tWR.
21. JEDEC and PC100 specify three clocks.
PDF: 09005aef8091e6d1
256Mb_sdr.pdf - Rev. R 10/12 EN
Micron Technology, Inc. reserves the right to change products or specifications without notice.
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© 1999 Micron Technology, Inc. All rights reserved.
MICRON [ MICRON TECHNOLOGY ]
