EDD5104ADTA-E Datasheet, PDF (23/49 Pages) Elpida Memory – 512M bits DDR SDRAM

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Read/Write Operations
Bank active
A read or a write operation begins with the bank active command [ACT]. The bank active command determines a
bank address and a row address. For the bank and the row, a read or a write command can be issued tRCD after
the ACT is issued.
Read operation
The burst length (BL), the /CAS latency (CL) and the burst type (BT) of the mode register are referred when a read
command is issued. The burst length (BL) determines the length of a sequential output data by the read command
that can be set to 2, 4, or 8. The starting address of the burst read is defined by the column address, the bank select
address which are loaded via the A0 to A12 and BA0, BA1 pins in the cycle when the read command is issued. The
data output timing are characterized by CL and tAC. The read burst start CL • tCK + tAC (ns) after the clock rising
edge where the read command are latched. The DDR SDRAM output the data strobe through DQS simultaneously
with data. tRPRE prior to the first rising edge of the data strobe, the DQS are driven Low from VTT level. This low
period of DQS is referred as read preamble. The burst data are output coincidentally at both the rising and falling
edge of the data strobe. The DQ pins become High-Z in the next cycle after the burst read operation completed.
tRPST from the last falling edge of the data strobe, the DQS pins become High-Z. This low period of DQS is
referred as read postamble.
t0
t1
t4
t5
t6
t7
t8
t9
CK
/CK
Command _NOP
tRCD
ACT NOP
READ
NOP
Address
Row
Column
tRPRE
DQS
DQ
BL = 2
BL = 4
out0 out1
tRPST
out0 out1 out2 out3
BL = 8
out0 out1 out2 out3 out4 out5 out6 out7
CL = 2
BL: Burst length
Read Operation (Burst Length)
Preliminary Data Sheet E0501E10 (Ver. 1.0)
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