AS4C256K16FO
®
Functional description
The AS4C256K16FO is a high-performance 4 megabit CMOS Dynamic Random Access Memory (DRAM) device organized as
262,144 words × 16 bits. The AS4C256K16FO is fabricated with advanced CMOS technology and designed with innovative
design techniques resulting in high speed, extremely low power and wide operating margins at component and system levels.
The AS4C256K16FO features a high-speed page mode operation in which high speed read, write and read-write are performed
on any of the 512
×
16 bits defined by the column address. The asynchronous column address uses an extremely short row
address capture time to ease the system-level timing constraints associated with multiplexed addressing. Output is tri-stated by a
column address strobe (CAS) which acts as an output enable independent of RAS. Very fast CAS to output access time eases
system design.
Refresh on the 512 address combinations of A0–A8 during an 8 ms period is accomplished by performing any of the following:
•
•
•
•
•
RAS-only refresh cycles
Hidden refresh cycles
CAS-before-RAS refresh cycles
Normal read or write cycles
Self-refresh cycles.
*
The AS4C256K16FO is available in standard 40-pin plastic SOJ and 44-pin TSOP II packages compatible with widely available
automated testing and insertion equipment. System level features include single power supply of 5V ± 10% tolerance and direct
interface with TTL logic families.
Logic block diagram
V
CC
GND
Refresh
controller
Column decoder
Sense amp
Data
I/O
buffer
I/O0 to I/O15
RAS
RAS clock
generator
CAS clock
generator
UCAS
LCAS
A0
A1
A2
A3
A4
A5
A6
A7
A8
Addreess buffers
OE
Row decoder
512×512×16
array
(4,194,304)
Substrate
bias generator
WE
WE clock
generator
Recommended operating conditions
Parameter
Supply voltage
Input voltage
Symbol
V
CC
GND
V
IH
V
IL
Min
4.5
0.0
2.4
–1.0
Typ
5.0
0.0
–
–
Max
5.5
0.0
V
CC
+ 1
0.8
Unit
V
V
V
V
* Self-refresh option is available for new generation device only. Contact Alliance for more information.
4/11/01; V.0.9.1
Alliance Semiconductor
P. 2 of 25
ALSC [ ALLIANCE SEMICONDUCTOR CORPORATION ]
