27S21AJC

Overview

The 27S21AJC is a one-time programmable read-only memory (OTP ROM) manufactured by Rochester Electronics, LLC. It features a storage capacity of 256 words by 4 bits. The device operates with a maximum access time of 60 nanoseconds and utilizes TTL-compatible logic levels for input and output signaling. This component is designed for applications requiring fixed data retention without the need for electrical erasure capabilities.

Feature Summary

• One-time programmable non-volatile memory architecture
• TTL-compatible logic level interface
• Three-state output capability

Applications

• Embedded system firmware storage
• Fixed lookup table implementation
• Configuration data retention in industrial controllers

Procurement Notes

Verify that the specific suffix 'JC' corresponds to the required temperature range and package variant. Confirm that the OTP nature of the device aligns with the final production requirements, as programming cannot be reversed. Ensure compatibility with existing TTL logic families in the target design.

Selection Notes

Select this component when a small, fixed data set requires non-volatile storage with fast access times. The TTL compatibility simplifies integration into legacy or standard digital systems. Consider the one-time programming constraint during the design phase to avoid costly re-spins if data changes are anticipated.

Part Context

Rochester Electronics specializes in sustaining end-of-life semiconductors. The 27S21AJC represents their role in maintaining supply for critical legacy components, such as the original AMD AM27S21, ensuring continued availability for long-life industrial and aerospace applications where newer replacements are not viable.

Replacement Considerations

The 27S21AJC serves as a direct replacement for the AMD AM27S21. Verify pinout and electrical specifications match exactly before substitution.