AS4LC4M4F1
®
Functional description
The AS4LC4M4F1 is a high performance 16-megabit CMOS Dynamic Random Access Memory (DRAM) device organized as 4,194,304
words × 4 bits. The device is fabricated using advanced CMOS technology and innovative design techniques resulting in high speed,
extremely low power and wide operating margins at component and system levels. The Alliance 16Mb DRAM family is optimized for use as
main memory in PC, workstation, router and switch applications.
This device features a high speed page-mode operation where read and write operations within a single row (or page) can be executed at
very high speed by toggling column addresses within that row. Row and column addresses are alternately latched into input buffers using the
falling edge of RAS and CAS inputs respectively. Also, RAS is used to make the column address latch transparent, enabling application of
column addresses prior to CAS assertion.
Refresh on the 2048 address combinations of A0 to A10 must be performed every 32 ms using:
• RAS-only refresh: RAS is asserted while CAS is held high. Each of the 2048 rows must be strobed. Outputs remain high impedence.
• Hidden refresh: CAS is held low while RAS is toggled. Refresh address is generated internally. Outputs remain low impedence with
previous valid data.
• CAS-before-RAS refresh (CBR): CAS is asserted prior to RAS. Refresh address is generated internally.
Outputs are high-impedence (OE and WE are don't care).
• Normal read or write cycles refresh the row being accessed.
• Self-refresh cycles
The AS4LC4M4F1 is available in the standard 24/26-pin plastic SOJ. TSOP 24/26-pin availability is to be determined. The AS4LC4M4F1
operates with a single power supply of 3.3V 0.3V and provides TTL compatible inputs and outputs.
Logic block diagram for 2K refresh
Data
I/O
buffers
VCC
Column decoder
Sense amp
GND
I/O0 to I/O3
RAS clock
generator
RAS
CAS
A0
A1
A2
A3
A4
A5
A6
A7
A8
OE
2048 × 2048 × 4
Array
CAS clock
generator
(16,777,216)
A9
A10
Substrate bias
generator
WE clock
generator
WE
Recommended operating conditions
Parameter
Symbol
VCC
Min
3.0
0.0
2.0
–0.5†
0
Nominal
Max
Unit
V
3.3
0.0
–
3.6
0.0
Supply voltage
Input voltage
GND
VIH
V
VCC+0.5V
0.8
V
VIL
–
V
Commercial
Industrial
–
70
Ambient operating temperature
TA
°C
-40
–
85
†
V
min -3.0V for pulse widths less than 5 ns. Recommended operating conditions apply throughout this document unlesss otherwise specified.
IL
5/16/01; v.1.0 Restored
Alliance Semiconductor
P. 2 of 14
ALSC [ ALLIANCE SEMICONDUCTOR CORPORATION ]
