2Gb: x4, x8, x16 DDR3 SDRAM - Micron

Table 83: Power-Down Modes
2Gb: x4, x8, x16 DDR3 SDRAM
Power-Down Mode
exit mode precharge power-down. A summary of the two power-down modes is listed in
Table 83 (page 182).
While in either power-down state, CKE is held LOW, RESET# is held HIGH, and a stable
clock signal must be maintained. ODT must be in a valid state but all other input signals
are “Don’t Care.” If RESET# goes LOW during power-down, the DRAM will switch out of
power-down mode and go into the reset state. After CKE is registered LOW, CKE must
remain LOW until tPD (MIN) has been satisfied. The maximum time allowed for powerdown
duration is tPD (MAX) (9 × tREFI). The power-down states are synchronously exited when CKE is registered HIGH (with a
required NOP or DES command). CKE must be maintained HIGH until tCKE has been
satisfied. A valid, executable command may be applied after power-down exit latency,
tXP, and tXPDLL have been satisfied. A summary of the power-down modes is listed below.
For specific CKE-intensive operations, such as repeating a power-down-exit-to-refreshto-power-down-entry
sequence, the number of clock cycles between power-down exit
and power-down entry may not be sufficient to keep the DLL properly updated. In addition
to meeting tPD when the REFRESH command is used between power-down exit
and power-down entry, two other conditions must be met. First, tXP must be satisfied
before issuing the REFRESH command. Second, tXPDLL must be satisfied before the
next power-down may be entered. An example is shown in Figure 105 (page 188).
DRAM State MR0[12] DLL State
Power-
Down Exit Relevant Parameters
Active (any bank open) “Don’t Care” On Fast tXP to any other valid command
Precharged
1 On Fast tXP to any other valid command
(all banks precharged) 0 Off Slow tXPDLL to commands that require the DLL to be
locked (READ, RDAP, or ODT on);
tXP to any other valid command
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2Gb_DDR3_SDRAM.pdf – Rev. P 2/12 EN 182 Micron Technology, Inc. reserves the right to change products or specifications without notice.
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