Microchip Technology AT28C256-15JU

Overview

AT28C256-15JU from Microchip Technology is an industrial-grade 256-Kbit paged parallel EEPROM organized as 32,768 × 8, featuring 150 ns read access time, 3 ms or 10 ms page write cycle time, and single 5V ±10% supply operation. It serves as nonvolatile program/data storage in microcontroller-based systems requiring byte- and page-level reprogrammability without external high-voltage circuitry.

For engineers reviewing the AT28C256-15JU datasheet, AT28C256-15JU pinout, AT28C256-15JU application, or AT28C256-15JU equivalent, key selection considerations include JEDEC-standard byte-wide pinout compatibility, DATA Polling/Toggle Bit write completion detection, hardware/software data protection, 10,000–100,000 endurance cycles, and industrial temperature range support (−40°C to +85°C).

Technical Context

The AT28C256-15JU implements a paged write architecture with a 64-byte internal page register, enabling up to 64 bytes to be latched and written in a single internal programming period. Address and data are internally latched on falling CE/WE edges, freeing the bus for concurrent operations.

It supports three write detection methods: DATA Polling (I/O7 complement-to-data behavior), Toggle Bit (I/O6 toggling during write), and software-controlled chip erase via 6-byte command sequence. Hardware protection includes VCC sense (<3.8 V inhibit), 5 ms power-on delay, and noise filtering on WE/CE inputs.

Key Specifications

Pinout & Package

AT28C256-15JU is supplied in a 32-lead PLCC (Plastic Leaded Chip Carrier) package with JEDEC-standard byte-wide pinout. Pin 1 identifier is located at corner with 45° chamfer per MS-016 Variation AE.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar paged parallel EEPROM applications.

Compared with AT28C256-15PU and AT28C256-15SU, the AT28C256-15JU offers superior mechanical stability and thermal dissipation in demanding industrial deployments due to its 32-lead PLCC construction, while maintaining identical functional behavior, timing, and protection features across all variants.

Availability

AT28C256-15JU is available at Aetrix Electronics and suitable for industrial PLC configuration storage, medical device calibration data retention, and telecom base station firmware patching requiring stable component supply, long-lifecycle assurance, and consistent JEDEC-compliant pinout.

Supply support for AT28C256-15JU includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Microchip Technology is a global provider of microcontrollers, analog components, and memory solutions, with a focus on embedded control and connectivity.

The AT28C256 product line delivers cost-effective, industrial-temperature parallel EEPROMs designed for legacy 8-bit system upgrades, firmware storage, and configuration retention in resource-constrained embedded applications.

FAQ

What is the maximum page write size supported by the AT28C256-15JU?

The AT28C256-15JU supports a maximum page write size of 64 bytes. This is enabled by its internal 64-byte page register, which allows up to 64 bytes to be loaded sequentially within a 150 µs window (tBLC) before the internal programming cycle begins. Each byte must reside on the same page, defined by address bits A6–A14, and A0–A5 select the specific byte positions within that page. The AT28C256-15JU does not support larger page sizes or partial-page writes outside this constraint.

How does DATA Polling work on the AT28C256-15JU during a write operation?

During a write operation, the AT28C256-15JU uses DATA Polling on I/O7 to signal write completion: an attempted read of the last-written byte returns the bitwise complement of the data until the internal programming finishes, after which true data appears. This allows the host system to poll I/O7 without timers or interrupts. The AT28C256-15JU guarantees this behavior across all operating conditions and endurance grades, and polling can begin immediately after write initiation.

Does the AT28C256-15JU require external high-voltage circuitry for programming?

No, the AT28C256-15JU operates from a single 5 V ±10% supply and requires no external high-voltage programming circuitry. All write, erase, and protection functions are implemented internally using charge-pump circuitry powered from VCC. The AT28C256-15JU achieves this while maintaining full JEDEC byte-wide pinout compatibility and supporting chip erase via a 6-byte software command sequence - eliminating external HV generators or complex programming adapters.

What is the purpose of the DC pins on the AT28C256-15JU PLCC package?

The DC pins (Pins 1 and 17) on the AT28C256-15JU PLCC package are designated "Don't Connect" - they have no internal bond wire and must remain unconnected in the PCB layout. Connecting them risks introducing noise coupling, ground loops, or mechanical stress that could compromise reliability. The AT28C256-15JU datasheet explicitly prohibits routing traces or placing vias to these pins, and their presence is solely for mechanical symmetry and JEDEC MS-016 package compliance.

How is endurance grade indicated on the AT28C256-15JU package marking?

The endurance grade of the AT28C256-15JU is encoded in the package marking suffix following "AT28C256@": a blank indicates 10,000 cycles at 10 ms write time; "E" indicates 100,000 cycles at 10 ms; and "F" indicates 10,000 cycles at 3 ms fast-write mode. The "15" in AT28C256-15JU refers only to the 150 ns read access time and does not denote endurance. The AT28C256-15JU's actual endurance rating must be verified from the top-side laser marking, not the orderable part number alone.