AM27S21AJC

Overview

The AM27S21AJC is a 1K-bit (256 x 4) One-Time Programmable Read-Only Memory (OTP ROM) manufactured by Advanced Micro Devices. It features parallel interface access with a maximum access time of 30 ns. The device operates within a supply voltage range of 4.75V to 5.25V and supports an industrial temperature range of 0°C to +70°C. It is housed in a 20-pin PLCC (9x9 mm) package, designed for general embedded system applications requiring standard non-volatile memory functionality.

Feature Summary

• Non-volatile OTP ROM technology for permanent data storage
• Parallel interface architecture for direct address and data bus connection
• Industrial temperature rating for reliable operation in varied environments

Applications

• General embedded system memory
• Microcontroller program storage
• Fixed logic replacement in digital circuits

Procurement Notes

Verify the specific manufacturer source, as multiple vendors list this part. Confirm the package type is 20-PLCC (9x9) and that the device is genuine AMD/Advanced Micro Devices product. Check for any ordering suffixes that may indicate different speed grades or packaging formats. Ensure the component is new and unused, as OTP devices cannot be reprogrammed once written.

Selection Notes

Select this component when a small, fixed capacity of 1K bits is required for firmware or lookup tables. The 30 ns access time suits moderate-speed microcontrollers. The parallel interface simplifies design compared to serial alternatives but requires more I/O pins. Consider the single-use nature of OTP technology during the prototyping phase before final production.

Part Context

This part belongs to the AM27S21 series of OTP ROMs from Advanced Micro Devices. These devices were commonly used in early computing and industrial control systems where small amounts of fixed code needed to be stored without the complexity of EPROM erasure equipment. The 'JC' suffix typically denotes the commercial/industrial temperature range and plastic leaded chip carrier package.

Replacement Considerations

Direct pin-to-pin replacements include other AM27S21 variants with compatible speed grades. Verify that substitute parts maintain the same 256x4 organization and 5V logic levels. Ensure the replacement is also OTP technology if reprogrammability is not required.