K4R881869M Datasheet, PDF (20/64 Pages) Samsung semiconductor – 288Mbit RDRAM 512K x 18 bit x 2*16 Dependent Banks Direct RDRAMTM

K4R881869M
Preliminary
Direct RDRAM^™
Precharge Mechanisms
Figure 13 shows an example of precharge with the ROWR
packet mechanism. The PRER command must occur a time
t_RAS after the ACT command, and a time t_RP before the next
ACT command. This timing will serve as a baseline aginst
which the other precharge mechanisms can be compared.
a0 = {Da,Ba,Ra}
a5 = {Da,Ba}
b0 = {Da,Ba,Rb}
T₀ T₁ T₂ T₃ T₄ T₅ T₆ T₇ T₈ T₉ T₁₀ T₁₁ T₁₂T₁₃ T₁₄ T₁₅ T₁₆T₁₇ T₁₈ T₁₉ T₂₀T₂₁ T₂₂ T₂₃ T₂₄T₂₅ T₂₆ T₂₇ T₂₈T₂₉ T₃₀ T₃₁ T₃₂T₃₃ T₃₄ T₃₅ T₃₆T₃₇ T₃₈ T₃₉ T₄₀T₄₁ T₄₂ T₄₃ T₄₄T₄₅ T₄₆ T₄₇
CTM/CFM
ROW2
..ROW0
ACT a0
PRER a5
ACT b0
COL4
..COL0
DQA8..0
DQB8..0
t_RAS
t_RP
t_RC
Figure 13: Precharge via PRER Command in ROWR Packet
Figure 14 (top) shows an example of precharge with a RDA
command. A bank is activated with an ROWA packet on the
ROW pins. Then, a series of four dualocts are read with RD
commands in COLC packets on the COL pins. The fourth of
these commands is a RDA, which causes the bank to auto-
matically precharge when the final read has finished. The
timing of this automatic precharge is equivalent to a PRER
command in an ROWR packet on the ROW pins that is
offset a time t_OFFP from the COLC packet with the RDA
command. The RDA command should be treated as a RD
command in a COLC packet as well as a simultaneous (but
offset) PRER command in an ROWR packet when analyzing
interactions with other packets.
Figure 14 (middle) shows an example of precharge with a
WRA command. As in the RDA example, a bank is acti-
vated with an ROWA packet on the ROW pins. Then, two
dualocts are written with WR commands in COLC packets
on the COL pins. The second of these commands is a WRA,
which causes the bank to automatically precharge when the
final write has been retired. The timing of this automatic
precharge is equivalent to a PRER command in an ROWR
packet on the ROW pins that is offset a time t_OFFP from the
COLC packet that causes the automatic retire. The WRA
command should be treated as a WR command in a COLC
packet as well as a simultaneous (but offset) PRER
command in an ROWR packet when analyzing interactions
with other packets. Note that the automatic retire is triggered
by a COLC packet a time t_RTR after the COLC packet with
the WR command unless the second COLC contains a RD
command to the same device. This is described in more
detail in Figure 17.
Figure 14 (bottom) shows an example of precharge with a
PREX command in an COLX packet. A bank is activated
with an ROWA packet on the ROW pins. Then, a series of
four dualocts are read with RD commands in COLC packets
on the COL pins. The fourth of these COLC packets
includes an COLX packet with a PREX command. This
causes the bank to precharge with timing equivalent to a
PRER command in an ROWR packet on the ROW pins that
is offset a time t_OFFP from the COLX packet with the PREX
command.
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Rev. 0.9 Jan. 2000