MT48LC8M32B2 查看數據表（PDF） - Micron Technology

零件编号

产品描述 (功能)

生产厂家

MT48LC8M32B2

SYNCHRONOUS DRAM

Micron Technology 

OPERATION

BANK/ROW ACTIVATION

Before any READ or WRITE commands can be is-

sued to a bank within the SDRAM, a row in that bank

must be “opened.” This is accomplished via the AC-

TIVE command, which selects both the bank and the

row to be activated. See Figure 3.

After opening a row (issuing an ACTIVE command),

a READ or WRITE command may be issued to that row,

subject to the tRCD specification. tRCD (MIN) should

be divided by the clock period and rounded up to the

next whole number to determine the earliest clock edge

after the ACTIVE command on which a READ or WRITE

command can be issued. For example, a tRCD specifi-

cation of 20ns with a 125 MHz clock (8ns period) results

in 2.5 clocks, rounded to 3. This is reflected in Figure 4,

which covers any case where 2 < tRCD (MIN)/tCK - 3.

(The same procedure is used to convert other specifi-

cation limits from time units to clock cycles.)

A subsequent ACTIVE command to a different row

in the same bank can only be issued after the previous

active row has been “closed” (precharged). The mini-

mum time interval between successive ACTIVE com-

mands to the same bank is defined by tRC.

A subsequent ACTIVE command to another bank

can be issued while the first bank is being accessed,

which results in a reduction of total row-access over-

head. The minimum time interval between successive

ACTIVE commands to different banks is defined by

tRRD.

PRELIMINARY

256Mb: x32

SDRAM

Figure 3

Activating a Specific Row in a

Specific Bank

CLK

CKE HIGH

CS#

RAS#

CAS#

WE#

A0-A11

ROW

ADDRESS

BA0, BA1

BANK

ADDRESS

Figure 4

Example: Meeting tRCD (MIN) When 2 < tRCD (MIN)/tCK - 3

CLK

COMMAND

T0

T1

T2

T3

tCK

ACTIVE

tCK

NOP

NOP

tRCD (MIN)

tRCD (MIN) +0.5 tCK

tCK

READ or

WRITE

tRCD (MIN) = 20ns, tCK = 8ns

tRCD (MIN) x tCK

where x = number of clocks for equation to be true.

DON’T CARE

09005aef80cd8e48

256MbSDRAMx32.p65 – Rev. B; Pub. 03/04

15

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

©2003 Micron Technology, Inc.

Share Link: