Intel JS28F256P33T95: A Comprehensive Technical Overview of the 256-Mbit Parallel NOR Flash Memory

The Intel JS28F256P33T95 stands as a prominent member of the StrataFlash® embedded memory family, representing a high-performance, 256-Mbit (32-MByte) Parallel NOR Flash memory device. Engineered for applications demanding reliable non-volatile storage and fast random access, this component is a cornerstone in systems requiring immediate code execution (XIP), robust firmware storage, and critical data retention. This overview delves into its key architectural features, performance characteristics, and primary applications.

Architectural Foundation and Core Features

Built on a mature and highly reliable multi-level cell (MLC) technology, the JS28F256P33T95 organizes its 256 megabits of memory into a uniform array of 128 blocks. A critical design element is its asymmetrical block architecture, which includes eight parameter blocks (typically 8 KWord each) and 120 main blocks (typically 64 KWord each). This structure provides flexibility, dedicating smaller blocks for frequently updated parameter storage while using larger blocks for main code or data, optimizing erase cycles and longevity.

The device features a 16-bit wide multiplexed address and data bus, which is standard for parallel NOR interfaces. This bus enables high-speed read operations and direct microprocessor support. The chip operates on a single 3.3V VCC supply (3.0V to 3.6V), simplifying power management design. Furthermore, it offers a versatile power-saving mode, significantly reducing standby current when the device is not actively selected, a crucial feature for power-sensitive embedded designs.

Performance and Operational Characteristics

Performance is a defining attribute of this memory solution. The JS28F256P33T95 offers fast access times, with a remarkable initial access speed (t_ACC) of just 95 ns. This low latency is fundamental for enabling efficient Execute-In-Place (XIP) operations, where a microprocessor can fetch and run code directly from the flash memory without the need to first copy it to RAM, thus saving system resources and boot time.

The device supports a standard command set for writing and erasing, which is managed through a write state machine (WSM) integrated onto the silicon. This onboard controller automates complex internal algorithms for programming and erase operations, significantly reducing the burden on the host processor. While write and block erase operations are considerably slower than reads—typical word programming time is 8.5µs and block erase time is 0.7s—this is characteristic of NOR Flash technology and is managed effectively through the WSM.

Reliability and Endurance

Designed for industrial and extended commercial temperature ranges, the JS28F256P33T95 is built for longevity and stability. It guarantees a minimum endurance of 100,000 program/erase (P/E) cycles per block, ensuring that firmware and parameters can be updated thousands of times over the product's lifespan. Data retention is specified at a minimum of 20 years, safeguarding critical information against loss for decades.

Target Applications

The combination of high density, fast random read access, and reliability makes this memory ideal for a wide array of demanding applications. Its primary use cases include:

Networking Equipment: Storing boot code, firmware, and configuration data in routers, switches, and gateways.

Industrial Automation and Control Systems: Hosting the application code for PLCs, motor drives, and human-machine interfaces (HMIs) in harsh environments.

Telecommunications Infrastructure: Providing robust storage for core and edge network infrastructure.

Automotive Systems: Used in pre-boot and diagnostic applications where reliability is paramount.

Legacy and Upgraded Embedded Systems: Serving as a reliable, high-density solution for a multitude of existing designs.

ICGOODFIND: The Intel JS28F256P33T95 remains a highly capable and robust parallel NOR Flash memory solution, offering an optimal balance of density, speed, and exceptional reliability for a generation of embedded systems that require deterministic performance and direct code execution.

Keywords:

1. Parallel NOR Flash

2. Execute-In-Place (XIP)

3. 256-Mbit

4. Asymmetrical Block Architecture

5. StrataFlash®