Datasheet
Read Burst Operation
DDR4 Read command supports bursts of BL8 (fixed), BC4 (fixed), and BL8/BC4 on-the-fly (OTF); OTF uses
address A12 to control OTF during the Read or Write (auto-precharge can be enabled or disabled).
A12 = 0, BC4 (BC4 = burst chop)
A12 = 1, BL8
Read commands can issue precharge automatically with a read with auto-precharge command (RDA); and is
enabled by A10 high.
Read command with A10 = 0 (RD) performs standard Read, bank remains active after read burst.
Read command with A10 = 1 (RDA) performs Read with auto-precharge, back goes in to precharge after
read burst.
DON'T CARE
NOTE 1. BL = 8, AL = 0, CL = 11, Preamble = 1t
CK
NOTE 2. Dout n = data-out from column n.
NOTE 3. DES commands are shown for ease of illustration; other commands may be valid at these times.
NOTE 4. BL8 setting activated by either MR0[A1:0 = 00] or MR0[A1:0 = 01] and A12 = 1 during READ command at T0.
NOTE 5. CA Parity = Disable, CS to CA Latency = Disable, Read DBI = Disable
T0 T1 T2 Ta0 Ta1 Ta2 Ta3 Ta4 Ta5
Ta6
Ta7
TRANSITIONING DATA
t
RPRE
t
RPST
Dout
n
Dout
n+1
Dout
n+2
Dout
n+3
Dout
n+4
Dout
n+5
Dout
n+6
Dout
n+7
RL = AL + CL
CL = 11
CK#
CK
DQS, DQS#
DQ
ADDR
CMD
Ta9
DESREAD DES DES DES DES DES DES DES DES DES
DES
Bank,
Col n
BG a
Bank Group
ADDR
Figure 89. READ Burst Operation RL = 11 (AL = 0, CL = 11, BL8)
DON'T CARE
NOTE 1. BL = 8, RL = 21, AL = (CL-1), CL = 11, Preamble = 1tCK
NOTE 2. Dout n = data-out from column n.
NOTE 3. DES commands are shown for ease of illustration; other commands may be valid at these times.
NOTE 4. BL8 setting activated by either MR0[A1:0 = 00] or MR0[A1:0 = 01] and A12 = 1 during READ command at T0.
NOTE 5. CA Parity = Disable, CS to CA Latency = Disable, Read DBI = Disable
T0 T1 Ta0 Ta1 Ta2 Ta3 Tb0 Tb1
Tb2
Tb3
TRANSITIONING DATA
t
RPRE
t
RPST
Dout
n
Dout
n+1
Dout
n+2
Dout
n+3
Dout
n+4
Dout
n+5
Dout
n+6
Dout
n+7
RL = AL + CL
AL = 10
CK#
CK
DQ
ADDR
CMD
Tb4
DESREAD DES DES DES DES DES DES DES DES DES
DES
Bank,
Col n
BG a
Bank Group
ADDR
DES
DQS, DQS#
Tb5 Tb6
CL = 11
Figure 90. READ Burst Operation RL = 21 (AL = 10, CL = 11, BL8)
AS4C256M16D4
Confidential
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Rev.1.0 Aug.2019