IBM0625164GT3B IBM0625404GT3B
IBM06254B4GT3B IBM0625804GT3B
Advance
256Mb Double Data Rate Synchronous DRAM
Electrical Characteristics & AC Timing for PC266 - Applicable Specifications
Expressed in Clock Cycles (0 °C ≤ TA ≤ 70 °C; VDDQ = 2.5V ± 0.2V; VDD = 2.5V ± 0.2V, See AC
Characteristics) (Part 2 of 2)
t
= 7.5ns
CK
Symbol
Parameter
Units
ns
Notes
Min
3.0
6
Max
t
Read postamble
4.5
1-4
1-4
1-4
RPST
t
Active to Precharge command
16000
t
t
RAS
CK
CK
t
Active to Active/Auto-refresh command period
9
RC
Auto-refresh to Active/Auto-refresh
command period
t
10
t
1-4
RFC
RCD
CK
t
Active to Read or Write delay
3
3
t
t
t
t
t
t
t
t
1-4
1-4
CK
CK
CK
CK
CK
CK
CK
CK
t
Precharge command period
RP
RRD
t
Active bank A to Active bank B command
Write recovery time
2
1-4
t
2
1-4
WR
DAL
WTR
t
Auto precharge write recovery + precharge time
Internal write to read command delay
Exit self-refresh to non-read command
Exit self-refresh to read command
Average Periodic Refresh Interval
QFC setup time on Read
5
1-4
t
1
1-4
t
t
10
200
1-4
XSNR
XSRD
1-4
t
7.8
8.25
4.5
µs
ns
ns
ns
ns
1-4, 8
1-4
REFI
t
6.75
3.0
QCS
QCH
t
QFC hold time on Read
1-4
t
Delay from CK edge of write command to QFC low on write
QFC hold time on write
4.0
1-4, 9
1-4, 10
QCSW
QCHW
t
1.25
2.0
1. Input slew rate = 1V/ns
2. The CK/CK input reference level (for timing reference to CK/CK) is the point at which CK and CK cross: the input reference level for
signals other than CK/CK, is V
REF.
3. Inputs are not recognized as valid until V
stabilizes.
REF
4. The Output timing reference level, as measured at the timing reference point indicated in AC Characteristics (Note 3) is V
.
TT
5. t and t transitions occur in the same access time windows as valid data transitions. These parameters are not referred to a
HZ
LZ
specific voltage level, but specify when the device is no longer driving (HZ), or begins driving (LZ).
6. The maximum limit for this parameter is not a device limit. The device operates with a greater value for this parameter, but system
performance (bus turnaround) degrades accordingly.
7. The specific requirement is that DQS be valid (HIGH, LOW, or some point on a valid transition) on or before this CK edge. A valid
transition is defined as monotonic and meeting the input slew rate specifications of the device. When no writes were previously in
progress on the bus, DQS will be transitioning from Hi-Z to logic LOW. If a previous write was in progress, DQS could be HIGH,
LOW, or transitioning from HIGH to LOW at this time, depending on t
.
DQSS
8. A maximum of eight Autorefresh commands can be posted to any given DDR SDRAM device.
9. QFC is enabled as soon as possible after the rising CK edge that registers the Write command.
10. QFC is disabled as soon as possible after the last valid DQS edge transitions Low.
©IBM Corporation. All rights reserved.
Use is further subject to the provisions at the end of this document.
29L0011.E36997
10/99
Page 59 of 75
IBM [ IBM ]
