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Product Detailed Parameters
- Description：OTP ROM, 256X4, 60NS, TTL
- Series：-
- Mfr：Rochester Electronics, LLC
- Package：Bulk
- Memory Type：-
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- Memory Size：-
- Memory Organization：-
- Memory Interface：-
- Clock Frequency：-
- Write Cycle Time - Word, Page：-
- Voltage - Supply：-
- Operating Temperature：-
- Mounting Type：-
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- Supplier Device Package：-
- Access Time：-
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Overview
The 27S21APC is a programmable read-only memory (PROM) integrated circuit manufactured by Rochester Electronics, LLC. This component features an OTP ROM architecture with a storage capacity of 256 words by 4 bits. It operates within a TTL-compatible logic family and supports a maximum access time of 60 nanoseconds. The device is designed for applications requiring non-volatile data retention without the need for complex programming hardware after initial configuration.
Feature Summary
- Non-volatile OTP ROM architecture for permanent data storage
- TTL-compatible logic levels for standard digital interface integration
- Fast 60ns access time suitable for high-speed reading operations
Applications
- Embedded system firmware storage
- Microcontroller boot code retention
- Hardware configuration data logging
Procurement Notes
Verify the specific suffix 'APC' against the manufacturer's official datasheet to confirm package type and temperature range. Ensure compatibility with existing TTL logic levels in the target design. Confirm that the OTP nature of the device aligns with the project's requirement for fixed, unchangeable program memory.
Selection Notes
Select this component when a small, fixed-size memory block is required for simple control logic or lookup tables. The 256x4 configuration is ideal for minimal address decoding needs. Consider the 60ns speed if the system clock allows for such timing margins without additional wait states.
Part Context
Rochester Electronics specializes in lifecycle management for semiconductors, often providing end-of-life parts. The 27S21APC represents a legacy PROM technology, serving as a replacement for obsolete original equipment manufacturer components in long-term industrial or aerospace applications where design changes are restricted.
Replacement Considerations
Direct pin-to-pin replacements may exist from other manufacturers offering equivalent 256x4 OTP PROMs. Verify electrical characteristics such as Vcc tolerance and output drive strength before substitution. Ensure the replacement part maintains the same TTL input/output specifications to avoid signal integrity issues.
