Intel JS28F640J3F75: A Comprehensive Technical Overview of the 64-Megabit Flash Memory Chip

The Intel JS28F640J3F75 stands as a significant component within the landscape of non-volatile memory solutions, representing a mature yet reliable 64-megabit (8-megabyte) NOR Flash memory chip. Engineered for applications demanding high reliability, robust performance, and straightforward interfacing, this device has been a cornerstone in numerous embedded systems, networking equipment, and industrial electronics.

Architecture and Core Technology

Fabricated on Intel's proven 0.13-micron NOR Flash process technology, the chip organizes its 64 megabits of memory into a uniform architecture of 131,072 words (or 2,097,152 bytes). A key feature of its design is the symmetrical sector structure. The memory array is divided into 128 individual, erasable blocks (sectors), each consisting of 64 Kbytes. This granularity provides system designers with exceptional flexibility for storing application code, boot code, and configuration data, allowing for efficient memory management and update procedures.

Performance and Key Specifications

The JS28F640J3F75 operates on a single 3.0V to 3.6V power supply, making it suitable for modern low-power designs. Its performance is characterized by fast access times. The chip offers a rapid 90-nanosecond maximum random access time, which is critical for systems that execute code directly from the flash memory (XIP - Execute-In-Place). This ensures minimal latency for the host processor.

For programming operations, the chip utilizes an efficient 4-word/8-byte write buffer. This feature significantly accelerates the programming process compared to single-byte programming, reducing overall system write times. The block erase operation is a fundamental capability, with each 64 Kbyte sector being erased in a typical time of 0.7 seconds.

Reliability and Endurance

A hallmark of this Intel memory chip is its exceptional durability and data retention. It is specified for a minimum of 100,000 program/erase cycles per sector, a figure that underscores its robustness for applications involving frequent firmware updates or data logging. Furthermore, the chip guarantees excellent data retention of up to 20 years, ensuring long-term data integrity even in harsh environmental conditions.

Software and Hardware Features

The JS28F640J3F75 supports the Common Flash Memory Interface (CFI), which allows host software to automatically query the device to discover its architecture, electrical characteristics, and supported commands. This simplifies system design and software driver development. The interface is a multiplexed address and data bus, adhering to a standard asynchronous SRAM-like protocol for easy integration.

To protect stored data, the chip incorporates several hardware and software locking mechanisms. Individual block locking allows specific sectors to be write-protected, safeguarding critical boot code or firmware from accidental corruption. Additional security features include an absolute protection mode during programming and a 64-bit unique device identifier.

Applications and Use Cases

This memory chip was designed for a wide array of applications where reliability is paramount. Its primary use cases include:

Networking Equipment: Storing boot code and firmware in routers, switches, and hubs.

Industrial Control Systems: Hosting application code in PLCs, instrumentation, and automotive systems.

Telecommunications Infrastructure: Providing firmware storage for base stations and communication controllers.

Embedded Computing: Serving as a primary code storage medium in single-board computers and set-top boxes.

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The Intel JS28F640J3F75 is a quintessential example of a high-reliability NOR Flash memory solution. Its combination of a robust 0.13-micron process, fast XIP performance, high endurance, and extensive data retention made it a trusted choice for a generation of critical embedded systems. While newer technologies offer higher densities, the JS28F640J3F75 remains a benchmark for durability and dependability in its class.

Keywords:

1. NOR Flash Memory

2. 64-Megabit

3. Execute-In-Place (XIP)

4. Program/Erase Endurance

5. Common Flash Interface (CFI)