®

4

ALLIANCE SEMICONDUCTOR

7/5/00

AS4LC4M16S0

AS4LC16M4S0

Commands

1

OP = operation code.

A0~A11 and BA0~BA1 program keys.

2

MRS can be issued only when all banks are precharged. A new command can be issued 1 clock cycle after MRS.

3

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

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

4

BA0~BA1: bank select addresses.

If A10/AP is High at row precharge, BA0 and BA1 are ignored and all banks are selected.

During read, write, row active, and prechage:

If BA0 and BA1 are Low, Bank A is selected.

If BA0 = Low and BA1 = High, Bank B is selected.

If BA0 = High and BA1 = Low, Bank C is selected.

If BA0 and BA1 are High, Bank D is selected.

5

A new read/write 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.

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

CS

RAS

CAS

WE

DQM

BA0/

BA1

A10

A9–A0

DQ

Note

Register

Mode register set

HL

L

L

L

X

Op code

X

1,2

Refresh

Auto refresh

H

H

L

L

L

H

X

–

X

–

X

3

Self

refresh

Entry

H

L

L

L

L

H

X

–

–

3

Exit

L

H

LH

H

H

X

–

–

3

H

XXX

X

–

–

3

Bank activate

H

H

L

L

H

H

X

V

row address

X

Read

Auto precharge disable

HH

L

H

L

H

X

V

L

column

address

X

4

Auto precharge enable

H

4,5

Write

Auto precharge disable

HH

L

H

L

L

X

V

L

column

address

Valid

4

Auto precharge enable

H

4,5

Burst stop

H

H

L

H

H

L

X

X

Active

6

Precharge

Selected bank

HH

L

L

H

L

X

VL

XX

4

All banks

X

H

Clock suspend or

active power down

Entry

H

L

H

XXX

XX

X

X

X

L

VVV

Exit

L

H

X

XXX

Precharge power

down mode

Entry

H

L

H

XXX

XX

X

X

X

LH

H

H

Exit

L

H

H

XXX

L

VVV

DQM

Write enable/output

enable

HH

X

XXX

H

XX

X

X

7

Write inhibit/Output

High-Z

No operation command

H

X

H

XXX

X

XX

X

X

LH

H

H

X