HM5259165B datasheet(13/63 Pages) ELPIDA

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HM5259165B/HM5259805B/HM5259405B-75/A6

Data Sheet E0118H10

CKE Truth Table

CKE

Current state

Command

n - 1

RAS

CAS

WE Address

Active

Clock suspend mode entry

××××

Any

Clock suspend

××××

Clock suspend

Clock suspend mode exit

××××

Idle

Auto-refresh command (REF)

LLLH

Idle

Self-refresh entry (SELF)

LLLLH

Idle

Power down entry

×××

Self refresh

Self refresh exit (SELFX)

×××

Power down

Power down exit

×××

Note:

H: V

IH.

L: V

IL.

×: V

IH or VIL.

Clock suspend mode entry: The SDRAM enters clock suspend mode from active mode by setting CKE to

Low. If command is input in the clock suspend mode entry cycle, the command is valid. The clock suspend

mode changes depending on the current status (1 clock before) as shown below.

ACTIVE clock suspend: This suspend mode ignores inputs after the next clock by internally maintaining

the bank active status.

READ suspend and READ with Auto-precharge suspend: The data being output is held (and continues to

be output).

WRITE suspend and WRIT with Auto-precharge suspend: In this mode, external signals are not

accepted. However, the internal state is held.

Clock suspend: During clock suspend mode, keep the CKE to Low.

Clock suspend mode exit: The SDRAM exits from clock suspend mode by setting CKE to High during the

clock suspend state.

IDLE: In this state, all banks are not selected, and completed precharge operation.

Auto-refresh command [REF]: When this command is input from the IDLE state, the SDRAM starts auto-

refresh operation. (The auto-refresh is the same as the CBR refresh of conventional DRAMs.) During the

auto-refresh operation, refresh address and bank select address are generated inside the SDRAM. For every

auto-refresh cycle, the internal address counter is updated. Accordingly, 8192 times are required to refresh

the entire memory. Before executing the auto-refresh command, all the banks must be in the IDLE state. In

addition, since the precharge for all banks is automatically performed after auto-refresh, no precharge

command is required after auto-refresh.

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