Microchip Technology AT28C256-15JU-T

Overview

AT28C256-15JU-T 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-T datasheet, AT28C256-15JU-T pinout, AT28C256-15JU-T application, or AT28C256-15JU-T equivalent, key selection criteria include JEDEC-standard 28-pin SOIC package compatibility, hardware/software data protection support, DATA Polling and Toggle Bit write completion detection, and industrial temperature range (–40°C to +85°C) operation.

Technical Context

The AT28C256-15JU-T implements a CMOS-based paged EEPROM architecture with internal 64-byte page register, automatic internal control timer for self-timed writes, and dual-line chip enable (CE) and output enable (OE) logic enabling bus contention avoidance. Its address decoding supports full 15-bit addressing (A0–A14), with A6–A14 defining page boundaries for 64-byte page writes.

Write operations are initiated by WE or CE low pulses under specific OE/CE/WE state combinations per Table 6-1, supporting byte write, page write (1–64 bytes within same page), and optional software-enabled chip erase. End-of-write detection is implemented via I/O7 DATA Polling (complement-to-data toggle) and I/O6 Toggle Bit behavior, both usable at any point during tWC.

Key Specifications

Pinout & Package

AT28C256-15JU-T is supplied in a 28-lead Small Outline Integrated Circuit (SOIC) package with JEDEC-standard byte-wide pinout. Pin 1 is located at the top-left corner adjacent to the notch or mark; body dimensions are 15.4 mm × 7.6 mm × 2.35 mm (max).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT28C256-15PU and AT28C256-15JU, the AT28C256-15JU-T offers optimized supply chain readiness for SMT production lines via EIA-481-compliant tape-and-reel delivery, while maintaining identical functional behavior and industrial temperature compliance.

Availability

AT28C256-15JU-T is available at Aetrix Electronics and suitable for industrial PLCs, medical diagnostics, automotive ECUs, and automated test equipment requiring stable component supply across extended product lifecycles.

Supply support for AT28C256-15JU-T 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 semiconductor company specializing in microcontrollers, analog devices, and nonvolatile memory solutions, with ISO 9001-certified manufacturing and design centers worldwide.

The AT28C256 belongs to Microchip's legacy parallel EEPROM product line, engineered for robust, pin-compatible replacement of obsolete EPROMs and SRAMs in industrial and automotive control systems requiring field-programmable nonvolatile storage.

FAQ

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

The AT28C256-15JU-T supports page write operations of 1 to 64 bytes per internal programming cycle. All bytes written in a single page operation must reside within the same 64-byte page boundary defined by address bits A6–A14. The device internally latches the address and data, then executes a self-timed write using its internal control timer - no external timing control is needed. This capability is confirmed in Section 6.8 and Figure 6-9 of the DS20006386B datasheet.

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

No, the AT28C256-15JU-T operates from a single 5 V ±10% supply and requires no external high-voltage programming circuitry. All write and erase functions are performed using standard logic-level signals. The only exception is the optional device identification area (7FC0h–7FFFh), which requires 12 V ±0.5 V applied to A9 for programming - but this is not used for normal operation. Standard byte and page writes use only VCC, CE, OE, WE, and data/address lines.

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

During a write cycle, reading the last-written byte from the AT28C256-15JU-T causes I/O7 to output the complement of the written data. Once the internal write completes, I/O7 returns to true data value. This allows software to poll I/O7 in a loop until the complement state disappears, confirming write completion without fixed delays. This behavior is electrically guaranteed and documented in Section 6.14 and Table 6-5 of the DS20006386B datasheet.

Is the AT28C256-15JU-T pin-compatible with the AT28C256-15PU?

Yes, the AT28C256-15JU-T and AT28C256-15PU share identical pin functions, signal timing, and electrical specifications per the DS20006386B datasheet. They differ only in package type: JU-T is 28-lead SOIC in tape-and-reel, while PU is 28-lead PDIP. Both use the same JEDEC-standard byte-wide pinout (A14–A0, I/O7–I/O0, CE, OE, WE, VCC, GND), enabling direct PCB footprint substitution with appropriate pad layout adaptation.

What endurance rating applies to the AT28C256-15JU-T based on its part marking?

The AT28C256-15JU-T carries no endurance suffix (e.g., "E" or "F") in its marking, indicating it is rated for 10,000 write cycles at 10 ms page write time per Section 7.1 and Table 6-4 of DS20006386B. The "15" denotes 150 ns access time, "JU" specifies 28-lead SOIC, and "T" indicates tape-and-reel packaging. Endurance is not user-selectable - it is a factory-trimmed characteristic tied to the specific wafer lot and process variant.