Microchip Technology AT28C256-15TU

Overview

AT28C256-15TU from Microchip Technology is an industrial-grade 256-Kbit paged parallel EEPROM organized as 32,768 × 8, featuring 150 ns read access time, 3–10 ms page write cycle, and single 5V ±10% supply operation. It supports hardware/software data protection, DATA polling, and toggle-bit write completion detection for embedded control and firmware storage applications.

For engineers reviewing the AT28C256-15TU datasheet, AT28C256-15TU pinout, AT28C256-15TU application, or AT28C256-15TU equivalent, key selection criteria include JEDEC byte-wide pin compatibility, 64-byte page register support, CMOS/TTL I/O compatibility, industrial temperature range (−40°C to +85°C), and endurance of 10,000 or 100,000 write cycles depending on variant.

Technical Context

The AT28C256-15TU implements a paged write architecture with an internal 64-byte latch that accepts sequential data within 150 µs per byte. Its dual-line chip enable (CE) and output enable (OE) control enables bus contention avoidance in shared-memory systems.

It integrates VCC sense (write inhibit below 3.8 V), 5 ms power-on delay, noise filtering (<15 ns pulse rejection), and optional software data protection using a 3-byte command sequence at fixed addresses (5555H/2AAAH). Device identification space (64 bytes at 7FC0H–7FFFH) requires A9 = 12 V for access.

Key Specifications

Pinout & Package

AT28C256-15TU is supplied in a 32-lead PLCC (Plastic Leaded Chip Carrier) package with JEDEC-standard byte-wide pinout. Pin 1 identifier is marked via corner chamfer; leads are gull-wing J-type with 1.27 mm pitch.

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 AT28C256-15TU offers identical functionality but differs exclusively in package form factor-PLCC provides superior thermal dissipation and socket compatibility for development, while PDIP and SOIC serve distinct mechanical integration needs.

Availability

AT28C256-15TU is available at Aetrix Electronics and suitable for industrial PLC configuration storage, legacy embedded system firmware backup, automotive ECU parameter tables, and point-of-sale terminal security keys requiring stable component supply across extended product lifecycles.

Supply support for AT28C256-15TU 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 components, and nonvolatile memory solutions, with a focus on reliability and long-term product support.

The AT28C256 series was designed as a drop-in upgrade path for EPROM and battery-backed SRAM in industrial and automotive systems, emphasizing robust write protection, JEDEC-compliant pinout, and wide-temperature operation.

FAQ

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

The AT28C256-15TU supports a maximum page write size of 64 bytes. This is enabled by its internal 64-byte page register, which latches sequential data as long as each byte arrives within 150 µs of the prior one. The AT28C256-15TU uses address bits A6–A14 to define the page boundary; all bytes in a single page write must reside within the same 64-byte-aligned address block.

Does the AT28C256-15TU require a 12 V supply for any operation?

The AT28C256-15TU operates from a single 5 V ±10% supply for normal read/write functions. A 12 V ±0.5 V supply on A9 is required only for accessing the optional 64-byte device identification area (7FC0H–7FFFH); this is not needed for standard memory operations. All other features-including software data protection, chip erase, and page write-function at 5 V.

How does DATA polling work on the AT28C256-15TU?

During a write cycle, reading the last-written address returns the complement of the stored data on I/O7. Once the internal programming completes, I/O7 outputs the true data value. This allows the host system to poll I/O7 without halting execution-no additional hardware or timers are required. The AT28C256-15TU guarantees this behavior across its full industrial temperature range.

Can the AT28C256-15TU be used as a direct replacement for standard SRAM in existing designs?

Yes-the AT28C256-15TU is accessed like a Static RAM for reads: assert CE and OE low, keep WE high, and sample data on I/O0–I/O7 after tACC (150 ns). Its JEDEC byte-wide pinout and CMOS/TTL compatibility allow drop-in replacement in many 8-bit systems. However, write cycles require explicit WE/CE sequencing and status polling, unlike volatile SRAM.

What endurance rating applies to the AT28C256-15TU?

The AT28C256-15TU is rated for either 10,000 or 100,000 write cycles, depending on the specific variant indicated by the package marking: blank = 10K @ 10 ms, "E" = 100K @ 10 ms, "F" = 10K @ 3 ms. The AT28C256-15TU carries the "15" speed grade and "TU" PLCC package designation; its endurance is confirmed as 10,000 cycles unless otherwise specified in the lot trace code.