MT48H16M16LFF-8 데이터 시트보기 (PDF) - Micron Technology

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MT48H16M16LFF-8

256Mb: x16 MOBILE SDRAM

Micron Technology 

COMMAND INHIBIT

The COMMAND INHIBIT function prevents new

commands from being executed by the SDRAM, re-

gardless of whether the CLK signal is enabled. The

SDRAM is effectively deselected. Operations already

in progress are not affected.

NO OPERATION (NOP)

The NO OPERATION (NOP) command is used to

perform a NOP to an SDRAM which is selected (CS# is

LOW). This prevents unwanted commands from being

registered during idle or wait states. Operations already

in progress are not affected.

LOAD MODE REGISTER

The mode register is loaded via inputs A0-A12 (A13

and A14 should be driven LOW to prevent Extended

Mode Register.) See mode register heading in the Reg-

ister Definition section. The LOAD MODE REGISTER

command can only be issued when all banks are idle,

and a subsequent executable command cannot be is-

sued until tMRD is met.

ACTIVE

The ACTIVE command is used to open (or activate)

a row in a particular bank for a subsequent access. The

value on the BA0, BA1 inputs selects the bank, and the

address provided on inputs A0-A12 selects the row.

This row remains active (or open) for accesses until a

PRECHARGE command is issued to that bank. A

PRECHARGE command must be issued before open-

ing a different row in the same bank.

READ

The READ command is used to initiate a burst read

access to an active row. The value on the BA0, BA1

inputs selects the bank, and the address provided on

inputs A0-A8 (x16) selects the starting column location.

The value on input A10 determines whether or not auto

precharge is used. If auto precharge is selected, the row

being accessed will be precharged at the end of the

READ burst; if auto precharge is not selected, the row

will remain open for subsequent accesses. Read data

appears on the DQs subject to the logic level on the

DQM inputs two clocks earlier. If a given DQM signal

was registered HIGH, the corresponding DQs will be

High-Z two clocks later; if the DQM signal was regis-

tered LOW, the DQs will provide valid data.

WRITE

The WRITE command is used to initiate a burst write

access to an active row. The value on the BA0, BA1

inputs selects the bank, and the address provided on

ADVANCE

256Mb: x16

MOBILE SDRAM

inputs A0-A8 (x16) selects the starting column location.

The value on input A10 determines whether or not

auto precharge is used. If auto precharge is selected,

the row being accessed will be precharged at the end of

the WRITE burst; if auto precharge is not selected, the

row will remain open for subsequent accesses. Input

data appearing on the DQs is written to the memory

array subject to the DQM input logic level appearing

coincident with the data. If a given DQM signal is regis-

tered LOW, the corresponding data will be written to

memory; if the DQM signal is registered HIGH, the

corresponding data inputs will be ignored, and a WRITE

will not be executed to that byte/column location.

PRECHARGE

The PRECHARGE command 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 a specified time (tRP) after 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,

BA1 select the bank. Otherwise BA0, 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.

AUTO PRECHARGE

Auto precharge is a feature which performs the

same individual-bank PRECHARGE function de-

scribed above, without requiring an explicit command.

This is accomplished by using A10 to enable auto

precharge in conjunction with a specific READ or WRITE

command. A PRECHARGE of the bank/row that is ad-

dressed with the READ or WRITE command is auto-

matically performed upon completion of the READ or

WRITE burst, except in the full-page burst mode, where

AUTO PRECHARGE does not apply. Auto precharge is

nonpersistent in that it is either enabled or disabled for

each individual READ or WRITE command.

Auto precharge ensures that the precharge is initi-

ated at the earliest valid stage within a burst. The user

must not issue another command to the same bank

until the precharge time (tRP) is completed. This is

determined as if an explicit PRECHARGE command

was issued at the earliest possible time, as described

for each burst type in the Operation section of this data

sheet.

AUTO REFRESH

AUTO REFRESH is used during normal operation of

the SDRAM and is analogous to CAS#-BEFORE-RAS#

(CBR) REFRESH in conventional DRAMs. This

256Mb: x16 Mobile SDRAM

MobileRamY26L_A.p65 – Pub. 5/02

12

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

©2002, Micron Technology, Inc.

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