General Description

The 27C256 is a high-speed 256K UV erasable and electrically

reprogrammable CMOS EPROM, ideally suited for applications

where fast turnaround, pattern experimentation

and low power consumption are important requirements.

The 27C256 is designed to operate with a single a5V power

supply with g10% tolerance. The CMOS design allows

the part to operate over Military Temperature Range.

The 27C256 is packaged in a 28-pin dual-in-line package

with transparent lid and a 32-pin windowed LCC. The transparent

lid allows the user to expose the chip to ultraviolet

light to erase the bit pattern. A new pattern can then be

written electrically into the device by following the programming

procedure.

This EPROM is fabricated with National's proprietary, time

proven CMOS double-poly silicon gate technology which

combines high performance and high density with low power

consumption and excellent reliability.

The 27C256 specified on this data sheet is fully compliant

with MIL-STD-883, Revision C.

Features

Y Clocked sense amps for fast access time down to

250 ns

Y Low CMOS power consumption

Ð Active power: 55 mW max

Ð Standby power: 0.55 mW max

Y Performance compatible to NSC800TM CMOS

microprocessor

Y Single 5V power supply

Y Pin compatible with NMOS 256K EPROMs

Y Fast and reliable programming (0.5 ms for most bytes)

Y Static operationÐno clocks required

Y TTL, CMOS compatible inputs/outputs

Y TRI-STATEÉ output

Y Optimum EPROM for total CMOS systems

Y Windowed DIP and LCC package options

Y Specifications guaranteed over full military temperature

range (b55§C to a125§C)

Y This device is processed in compliance with SMD

86063, and the DIP version is dual marked