Functional description
The AS4C1M16F5 is a high performance 16-megabit CMOS Dynamic Random Access Memory (DRAM) organized as
1,048,576 words × 16 bits. The AS4C1M16F5 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 personal and portable PCs, workstations, and multimedia
and router switch applications.
The AS4C1M16F5 features high speed page mode operation where read and write operations within a single row (or page)
can be executed at very high speed (15 ns from XCAS)by toggling column addresses within that row. Row and column
addresses are alternately latched into input buffers using the falling edge of RAS and xCAS inputs respectively. Also, RAS is used
to make the column address latch transparent, enabling application of column addresses prior to xCAS assertion.
The
AS4C1M16F5 provides dual UCAS and LCAS for independent byte control of read and write access.
Refresh on the 1024 address combinations of A0 to A9 must be performed every 16 ms using:
•
RAS-only refresh: RAS is asserted while xCAS is held high. Each of the 1024 rows must be strobed. Outputs remain high impedence.
• Hidden refresh:
xCAS is held low while RAS is toggled. Outputs remain low impedence with previous valid data.
•
CAS-before-RAS refresh (CBR): At least one xCAS 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.
The AS4C1M16F5 is available in the standard 42-pin plastic SOJ and the 44/50-pin TSOP II packages, respectively. It operates
with a single power supply of 5V ± 0.5V. The device provides TTL compatible inputs and outputs.
