AS7C331MNTF32A datasheet(4/18 Pages) ALSC

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AS7C331MNTF32A/36A

12/23/04, v 1.2

Alliance Semiconductor

P. 4 of 18

Functional Description

The AS7C331MNTF32A/36A family is a high performance CMOS 32 Mbit synchronous Static Random Access Memory

(SRAM) organized as 1,048,576 words × 32 or 36 bits and incorporates a LATE Write.

This variation of the 32Mb+ synchronous SRAM uses the No Turnaround Delay (NTD™) architecture, featuring an enhanced

write operation that improves bandwidth over flowthrough burst devices. In a normal flowthrough burst device, the write data,

command, and address are all applied to the device on the same clock edge. If a read command follows this write command,

the system must wait for one dead cycle for valid data to become available. This dead cycle can significantly reduce overall

bandwidth for applications requiring random access or read-modify-write operations.

NTD™ devices use the memory bus more efficiently by introducing a write latency which matches the one-cycle flow-

through read latency. Write data is applied one cycle after the write command and address, allowing the read pipeline to clear.

With NTD™, write and read operations can be used in any order without producing dead bus cycles.

Assert R/W low to perform write cycles. Byte write enable controls write access to specific bytes, or can be tied low for full 36

bit writes. Write enable signals, along with the write address, are registered on a rising edge of the clock. Write data is applied

to the device one clock cycle later. Unlike some asynchronous SRAMs, output enable OE does not need to be toggled for write

operations; it can be tied low for normal operations. Outputs go to a high impedance state when the device is de-selected by

any of the three chip enable inputs.

Use the ADV (burst advance) input to perform burst read, write and deselect operations. When ADV is high, external addresses, chip

select, R/W pins are ignored, and internal address counters increment in the count sequence specified by the LBO control. Any

device operations, including burst, can be stalled using the CEN=1, the clock enable input.

The AS7C331MNTF32A/36A operates with a 3.3V ± 5% power supply for the device core (VDD). DQ circuits use a separate

power supply (VDDQ) that operates across 3.3V or 2.5V ranges. These devices are available in a 100-pin TQFP package a.

TQFP Capacitance

*Guranteed not tested

TQFP thermal resistance

Parameter

Symbol

Test conditions

Min

Max

Unit

Input capacitance

CIN*

Vin = 0V

I/O capacitance

CI/O*

Vin = Vout = 0V

Description

Conditions

Symbol

Typical

Units

Thermal resistance

(junction to ambient)1

1 This parameter is sampled

Test conditions follow standard test methods and

procedures for measuring thermal impedance,

per EIA/JESD51

1–layer

θJA

°C/W

4–layer

θJA

°C/W

Thermal resistance

(junction to top of case)1

θJC

°C/W

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