27C256-20B/XA

Overview

The AT27C256-20B/XA is a CMOS 256K-bit Electrically Programmable Read Only Memory (EPROM) manufactured by Microchip Technology. It is organized as 32K words by 8 bits and features a parallel interface with separate chip enable and output enable controls. The device supports a maximum access time of 20 ns, enabling high-speed operation without wait states for sophisticated microprocessors. It operates within a supply voltage range of 4.5 V to 5.5 V and includes an auto-insertion-compatible plastic package.

Feature Summary

• High-speed performance with access times as fast as 20 ns
• CMOS technology ensures low power consumption in both active and standby modes
• Supports factory programming with an auto-insertion-compatible plastic package

Applications

• Industrial control systems requiring non-volatile code storage
• Automotive electronics operating in extended temperature ranges
• Embedded systems utilizing sophisticated microprocessors

Procurement Notes

Verify the specific suffix 'XA' against official Microchip documentation to confirm it denotes the industrial temperature grade (-40°C to +85°C). Ensure the ordering information matches the exact pinout and package type required for your design. Confirm RoHS compliance status through the manufacturer's current datasheet before finalizing procurement.

Selection Notes

Select this component when a high-speed EPROM solution is required for storing firmware or data that does not need frequent field updates. The 20 ns speed rating allows integration with fast processors without introducing latency. Consider the 28-pin DIP or SOIC package options based on your board layout constraints and assembly requirements.

Part Context

This part belongs to the AT27C256R series of 256K-bit EPROMs from Microchip Technology. These devices are designed to replace older NMOS EPROMs with faster, lower-power CMOS alternatives. The series offers various speed grades and package options to accommodate different system performance needs and physical form factors.

Replacement Considerations

Direct replacements include other 27C256 variants from Microchip or compatible manufacturers such as Intel or National Semiconductor, provided they match the 20 ns speed and 5V logic levels. Verify pin compatibility and ensure the substitute supports the required industrial temperature range.