DRAM

DRAM

DRAM

DRAM

DRAM

AS4LC4M16

Austin Semiconductor, Inc.

AustinSemiconductor,Inc.reservestherighttochangeproductsorspecificationswithoutnotice.

3

AS4LC4M16

Rev. 1.0 7/02

GENERAL DESCRIPTION

The 4 Meg x 16 DRAM is a high-speed CMOS, dynamic

random-access memory device containing 67,108,864 bits and

designed to operate from 3V to 3.6V. The device is functionally

organized as 4,194,304 locations containing 16 bits each. The

4,194,304 memory locations are arranged in 4,096 rows by 1,024

columns. During READ or WRITE cycles, each location is

uniquely addresses via the address bits: 12 row-address bits

(A0 - A11) and 10 column-address bits (A0 - A9). In addition,

both byte and word accesses are supported via the two CAS\

pins (CASL\ and CASH\).

The CAS\ functionality and timing related to address and

control functions (e.g., latching column addresses or selecting

CBR REFRESH) is such that the internal CAS\ signal is

determined by the first external CAS\ signal (CASL\ or CASH\)

to transition LOW and the last to transition back HIGH. The

CAS\ functionality and timing related to driving or latching data

is such that each CAS\ signal independently controls the

associated either DQ pins.

The row address is latched by the RAS\ signal, then the

column address is latched by CAS\. This device provides

EDO-PAGE-MODE operation, allowing for fast successive data

operations (READ, WRITE or READ-MODIFY-WRITE) within

a given row.

The 4 Meg x 16 DRAM must be refreshed periodically in

order to retain stored data.

DRAM ACCESS

Each location in the DRAM is uniquely addressable, as

mentioned in the General Description. Use of both CAS\

signals resulted in a word access via the 16 I/O pins

(DQ0 - DQ15). Using only one of the two signals results in a

BYTE access cycle. CASL\ transitioning LOW selects an

access cycle for the lower byte (DQ0 - DQ7), and CASH\

transitioning LOW selects an access cycle for the upper byte

(DQ8-DQ15). General byte and word access timing is shown in

Figures 1 and 2.

FIGURE 1: WORD and BYTE WRITE Example