HYB25D512400AT Datasheet, PDF (26/76 Pages) Infineon Technologies AG – 512Mbit Double Data Rate SDRAM

CK
CK
Command
Address
DQS
DQ
HYB25D512[16/40/80]0AT–[6/7/7F]
Functional Description
CAS Latency = 2
Read
BAa, COL n
Read
BAa, COL x
CL=2
Read
BAa, COL b
Read
BAa, COL g
NOP
NOP
DOa-n DOa-n’ DOa-x DOa-x’ DOa-b DOa-b’ DOa-g
CK
CK
Command
Address
DQS
DQ
CAS Latency = 2.5
Read
BAa, COL n
Read
Read
BAa, COL x
BAa, COL b
CL=2.5
Read
BAa, COL g
NOP
NOP
DOa-n DOa-n’ DOa-x DOa-x’ DOa-b DOa-b’
DO a-n, etc. = data out from bank a, column n etc.
n' etc. = odd or even complement of n, etc. (i.e., column address LSB inverted).
Reads are to active rows in any banks.
Shown with nominal t_AC, t_DQSCK, and t_DQSQ.
Don’t Care
Figure 12 Random Read Accesses: CAS Latencies (Burst Length = 2, 4 or 8)
Data from any Read burst may be truncated with a Burst Terminate command, as shown on Figure 13. The Burst
Terminate latency is equal to the read (CAS) latency, i.e. the Burst Terminate command should be issued x cycles
after the Read command, where x equals the number of desired data element pairs.
Data from any Read burst must be completed or truncated before a subsequent Write command can be issued. If
truncation is necessary, the Burst Terminate command must be used, as shown on Figure 14. The example is
shown for t_DQSS(min). The t_DQSS(max) case, not shown here, has a longer bus idle time. t_DQSS(min) and t_DQSS(max) are
defined in Chapter 3.5.3.
A Read burst may be followed by, or truncated with, a Precharge command to the same bank (provided that Auto
Precharge was not activated). The Precharge command should be issued x cycles after the Read command,
where x equals the number of desired data element pairs (pairs are required by the 2n prefetch architecture). This
is shown on Figure 15 for Read latencies of 2 and 2.5. Following the Precharge command, a subsequent
command to the same bank cannot be issued until t_RP is met. Note that part of the row precharge time is hidden
during the access of the last data elements.
Data Sheet
26
Rev. 1.0, 2004-03