AS4C4M4EOQ

AS4C4M4E1Q

®

3/22/01; v.1.0

Alliance Semiconductor

P. 2 of 16

Functional description

The 4C4M4EOQ, and AS4C4M4E1Q are high performance 16-megabit CMOS Quad CAS Dynamic Random Access Memories (DRAM)

organized as 4,194,304 words × 4 bits. The devices are 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.

These products feature 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.

Extended data out (EDO) read mode enables 50 MHz operation using 50 ns devices. Four individual CAS pins allow for separate I/O

operation which enables the device to operate in parity mode. In contrast to 'fast page mode' devices, data remains active on outputs after

CAS is de-asserted high, giving system logic more time to latch the data. Use OE and WE to control output impedance and prevent bus

contention during read-modify-write and shared bus applications. Outputs also go to high impedance at the last occurrance of RAS and CAS

going high.

Refresh on the 4096 address combinations of A0 to A11 must be performed every 64 ms using:

•RAS-only refresh: RAS is asserted while CAS is held high. Each of the 4096 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): At least one 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

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): At least one 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 4C4M4EOQ and AS4C4M4E1Q are available in the standard 28-pin plastic SOJ and 28-pin plastic TSOP packages. The 4C4M4EOQ and

AS4C4M4E1Q operate with a single power supply of 5V ± 0.5V. All provide TTL compatible inputs and outputs.