27C256-25/SO277

Overview

The Microchip Technology 27C256-25/SO is a CMOS 256K-bit Electrically Programmable Read Only Memory (EPROM). It is organized as 32K words by 8 bits. The device supports access times of less than 90 ns, with the specific -25 suffix indicating a maximum access time of 250 ns. It operates on a single 5V supply and features low power consumption with 20 mA active current and 100 µA standby current. The component is housed in a 28-pin SOIC package and is designed for industrial temperature ranges.

Feature Summary

• CMOS technology ensures low power consumption and high reliability for system integration.
• High-speed performance allows sophisticated microprocessors to operate without wait states.
• Separate chip enable and output enable controls provide flexible memory management.

Applications

• Industrial control systems requiring non-volatile code storage
• Embedded applications needing reliable program memory
• Automotive electronics operating in harsh environments

Procurement Notes

Verify the exact speed grade suffix against the datasheet, as standard 27C256 devices typically offer faster access times than 250 ns. Confirm the package type matches the required PCB footprint. Ensure programming equipment compatibility with OTP EPROM algorithms. Check for automotive qualification requirements if deploying in vehicle systems. Validate RoHS compliance status for the specific manufacturing batch.

Selection Notes

Select this component when a cost-effective, high-density non-volatile memory solution is required for storing firmware or fixed data. Consider the 250 ns access time constraint against the target processor's clock speed to determine if wait states are necessary. Evaluate the 28-pin SOIC package availability against board space limitations. Compare power specifications against battery-operated constraints if applicable.

Part Context

This part belongs to the Microchip 27C series of EPROMs, which are widely used for storing application code that does not require frequent updates. The 27C256 variant provides 256 kilobits of storage capacity. It serves as a bridge between older mask-programmed ROMs and modern Flash technologies, offering a balance of density and ease of use for legacy or specific industrial designs.

Replacement Considerations

Direct pin-compatible replacements include other 27C256 variants from different manufacturers such as Intel or National Semiconductor, provided the access time meets system requirements. Verify voltage levels and package dimensions before substitution. Note that newer Flash-based alternatives may offer reprogrammability but might require interface changes.