1Gb: x8, x16 Automotive DDR2 SDRAM - Micron

READ with auto
precharge enabled/
WRITE with auto
precharge enabled:
The READ with auto precharge enabled or WRITE with auto precharge
enabled states can each be broken into two parts: the access
period and the precharge period. For READ with auto precharge,
the precharge period is defined as if the same burst was
executed with auto precharge disabled and then followed with
the earliest possible PRECHARGE command that still accesses all
of the data in the burst. For WRITE with auto precharge, the precharge
period begins when t WR ends, with t WR measured as if
auto precharge was disabled. The access period starts with registration
of the command and ends where the precharge period
(or t RP) begins. This device supports concurrent auto precharge
such that when a READ with auto precharge is enabled or a
WRITE with auto precharge is enabled, any command to other
banks is allowed, as long as that command does not interrupt
the read or write data transfer already in process. In either case,
all other related limitations apply (contention between read data
and write data must be avoided).
The minimum delay from a READ or WRITE command with auto precharge enabled to
a command to a different bank is summarized in Table 39 (page 70).
4. REFRESH and LOAD MODE commands may only be issued when all banks are idle.
5. Not used.
6. All states and sequences not shown are illegal or reserved.
7. READs or WRITEs listed in the Command/Action column include READs or WRITEs with
auto precharge enabled and READs or WRITEs with auto precharge disabled.
8. A WRITE command may be applied after the completion of the READ burst.
9. Requires appropriate DM.
10. The number of clock cycles required to meet tWTR is either two or tWTR/ tCK, whichever
is greater.
Table 39: Minimum Delay with Auto Precharge Enabled
From Command (Bank n) To Command (Bank m)
Minimum Delay
(with Concurrent Auto Precharge) Units
WRITE with auto precharge READ or READ with auto precharge (CL - 1) + (BL/2) + tWTR tCK WRITE or WRITE with auto precharge (BL/2) tCK PRECHARGE or ACTIVATE 1 tCK READ with auto precharge READ or READ with auto precharge (BL/2) tCK WRITE or WRITE with auto precharge (BL/2) + 2 tCK PRECHARGE or ACTIVATE 1 tCK DESELECT
1Gb: x8, x16 Automotive DDR2 SDRAM
Commands
The DESELECT function (CS# HIGH) prevents new commands from being executed by
the DDR2 SDRAM. The DDR2 SDRAM is effectively deselected. Operations already in
progress are not affected. DESELECT is also referred to as COMMAND INHIBIT.
PDF: 09005aef840eff89
1gbddr2_ait_aat.pdf – Rev. C 7/11 EN 70 Micron Technology, Inc. reserves the right to change products or specifications without notice.
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