4

ALLIANCE SEMICONDUCTOR

7/5/00

AS4LC2M8S1

AS4LC1M16S1

Operating modes

1

OP= operation code.

A0~A11 see page 5.

2

MRS can be issued only when both banks are precharged and no data burst is ongoing. A new command can be issued 2 clock cycles after MRS.

3

Auto refresh functions similarly to CBR DRAM refresh. However, precharge is automatic.

Auto/self refresh can only be issued after both banks are precharged.

4

A11: bank select address. If low during read, write, row active and precharge, bank A is selected.

If high during those states, bank B is selected. Both banks are selected and A11 is ignored if A10 is high during row precharge.

5

A new read/write/deac command to the same bank cannot be issued during a burst read/write with auto precharge.

6

Burst stop command valid at every burst length except full-page burst.

7

DQM sampled at positive edge of CLK. Data-in may be masked at every CLK (Write DQM latency is 0).

Data-out mask is active 2 CLK cycles after issuance. (Read DQM latency is 2).

Command

CKEn-1 CKEn

CS

RAS

CAS

WE

DQM

A11

A10

A9–A0

Note

Mode register set

H

X

L

L

L

L

X

Op code

1,2

Auto refresh

H

H

L

L

L

H

X

X

3

Self

refresh

Entry

H

LLL

L

H

X

X

3

Exit

L

H

LH

H

H

X

X

3

HX

X

X

X

X

3

Bank activate

H

X

L

L

H

H

X

V

*

* V = Valid.

row address

Read

Auto precharge disable

H

X

LH

LH

X

V

L

column

address

4

Auto precharge enable

H

4,5

Write

Auto precharge disable

HX

L

H

L

L

X

V

L

column

address

4

Auto precharge enable

H

4,5

Burst stop

H

X

L

H

H

L

X

X

6

Precharge

Selected bank

HX

L

L

H

L

X

VL

X

Both banks

X

H

Clock suspend or

active power down

Entry

H

L

HX

X

X

X

X

LV

V

V

X

Exit

L

H

XX

XX

X

Precharge power

down mode

Entry

H

L

HX

X

X

X

X

LH

H

H

X

Exit

L

H

HX

X

X

X

LH

H

H

X

DQM

H

XX

XX

XVX

X

X

7

No operation command

H

X

HX

X

X

X

X

LH

H

H

X