MT48LC2M32B2 datasheet(21/53 Pages) MICRON

21 / 53 page

64Mb: x32 SDRAM

Micron Technology, Inc., reserves the right to change products or specifications without notice.

64MSDRAMx32_5.p65 – Rev. B; Pub. 6/02

64Mb: x32

SDRAM

Fixed-length or full-page WRITE bursts can be trun-

cated with the BURST TERMINATE command. When

truncating a WRITE burst, the input data applied coin-

cident with the BURST TERMINATE command will be

ignored. The last data written (provided that DQM is

LOW at that time) will be the input data applied one

clock previous to the BURST TERMINATE command.

This is shown in Figure 19, where data n is the last

desired data element of a longer burst.

Figure 21

Power-Down

DON’T CARE

tRAS

tRCD

tRC

All banks idle

Input buffers gated off

Exit power-down mode.

(

)

(

)

(

)

(

)

(

)

(

)

tCKS

> tCKS

COMMAND

NOP

ACTIVE

Enter power-down mode.

NOP

CLK

CKE

(

)

(

)

(

)

(

)

Figure 20

PRECHARGE Command

Figure 19

Terminating a WRITE Burst

CLK

COMMAND

ADDRESS

BANK,

COL n

WRITE

BURST

TERMINATE

COMMAND

DIN

(ADDRESS)

(DATA)

NOTE: DQMs are LOW.

PRECHARGE

The PRECHARGE command (Figure 20) is used to

deactivate the open row in a particular bank or the

open row in all banks. The bank(s) will be available for

a subsequent row access some specified time (tRP) af-

ter the PRECHARGE command is issued. Input A10

determines whether one or all banks are to be

precharged, and in the case where only one bank is to

be precharged, inputs BA0 and BA1 select the bank.

When all banks are to be precharged, inputs BA0 and

BA1 are treated as “Don’t Care.” Once a bank has been

precharged, it is in the idle state and must be activated

prior to any READ or WRITE commands being issued to

that bank.

POWER-DOWN

Power-down occurs if CKE is registered LOW coinci-

dent with a NOP or COMMAND INHIBIT when no ac-

cesses are in progress (see Figure 21). If power-down

occurs when all banks are idle, this mode is referred to

as precharge power-down; if power-down occurs when

there is a row active in either bank, this mode is referred

to as active power-down. Entering power-down deacti-

vates the input and output buffers, excluding CKE, for

maximum power savings while in standby. The device

may not remain in the power-down state longer than

the refresh period (64ms) since no refresh operations

are performed in this mode.

The power-down state is exited by registering a NOP

or COMMAND INHIBIT and CKE HIGH at the desired

clock edge (meeting tCKS).

CS#

WE#

CAS#

RAS#

CKE

CLK

A10

HIGH

All Banks

Bank Selected

A0–A9

BA0, 1

BANK

ADDRESS

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