NTC Proprietary
Level: Property
DDR3(L)-2Gb SDRAM
NT5CB(C)256M8JQ/NT5CB(C)128M16JR
Power-Down Modes
Power-Down Entry and Exit
Power-Down is synchronously entered when CKE is registered low (along with NOP or Deselect command). CKE is not
allowed to go low while mode register set command, MPR operations, ZQCAL operations, DLL locking or read/write
operation are in progress. CKE is allowed to go low while any of other operation such as row activation, precharge or auto
precharge and refresh are in progress, but power-down IDD spec will not be applied until finishing those operation.
The DLL should be in a locked state when power-down is entered for fastest power-down exit timing. If the DLL is not locked
during power-down entry, the DLL must be reset after exiting power-down mode for proper read operation and synchronous
ODT operation. DRAM design provides all AC and DC timing and voltage specification as well as proper DLL operation with
any CKE intensive operations as long as DRAM controller complies with DRAM specifications.
During Power-Down, if all banks are closed after any in progress commands are completed, the device will be in precharge
Power-Down mode; if any bank is open after in progress commands are completed, the device will be in active Power-Down
mode.
Entering Power-down deactivates the input and output buffers, excluding CK, CK, ODT, E, and REET. To protect DRAM
internal delay on CKE line to block the input signals, multiple NOP or Deselect commands are needed during the CKE switch
off and cycle(s) after, this timing period are defined as tCPDED. CKE_low will result in deactivation of command and address
receivers after tCPDED has expired.
Power-Down Entry Definitions
Status of DRAM
MRS bit A12
DLL
PD Exit
Relevant Parameters
Active
Don't Care
On
Fast
tXP to any valid command.
(A Bank or more open)
tXP to any valid command. Since it is in precharge state,
commands here will be ACT, AR, MRS/EMRS, PR, or PRA.
tXPDLL to commands who need DLL to operate, such as
RD, RDA, or ODT control line.
Precharged
0
1
Off
On
Slow
Fast
(All Banks Precharged)
Precharged
tXP to any valid command.
(All Banks Precharged)
Also the DLL is disabled upon entering precharge power-down (Slow Exit Mode), but the DLL is kept enabled during
precharge power-down (Fast Exit Mode) or active power-down. In power-down mode, CKE low, REET high, and a stable
clock signal must be maintained at the inputs of the DDR3(L) SDRAM, and ODT should be in a valid state but all other input
signals are “Don’t care” (If REET goes low during Power-Down, the DRAM will be out of PD mode and into reset state).
CKE low must be maintain until tCKE has been satisfied. Power-down duration is limited by 9 times tREFI of the device.
Version 1.4
05/2019
61
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