Microchip Technology AT28C256-15TU-T

Overview

AT28C256-15TU-T from Microchip Technology is an industrial-grade 256-Kbit paged parallel EEPROM organized as 32,768 × 8, featuring 150 ns read access time, 3–10 ms page write cycle, and single 5V ±10% supply operation. It supports hardware/software data protection and DATA Polling for end-of-write detection, used in embedded system firmware storage and configuration retention.

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

Technical Context

The AT28C256-15TU-T implements a paged architecture with an internal 64-byte latch enabling simultaneous multi-byte writes without bus hold. Its dual-line chip enable (CE) and output enable (OE) control allows flexible bus contention management during read operations.

Write completion is verified via DATA Polling on I/O7 (complement-to-data during write, true data after completion) or Toggle Bit behavior on I/O6, both usable at any point during the internal programming period. Hardware protection includes VCC sense (<3.8 V inhibits write), 5 ms power-on delay, and noise filtering on WE/CE inputs.

Key Specifications

Pinout & Package

AT28C256-15TU-T is supplied in a 32-lead PLCC (Plastic Leaded Chip Carrier) package with JEDEC-standard byte-wide pinout. Pin 1 identifier is marked on top surface; leads are J-formed with coplanarity ≤0.102 mm.

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-T offers superior mechanical stability and thermal cycling resistance due to its 32-lead PLCC construction-critical for long-life industrial deployments where solder joint reliability under thermal stress is paramount.

Availability

AT28C256-15TU-T is available at Aetrix Electronics and suitable for industrial PLC configuration storage, medical device calibration data retention, and automotive body control module firmware backup requiring stable component supply across extended production lifecycles.

Supply support for AT28C256-15TU-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.

The AT28C256 product line delivers high-reliability parallel EEPROMs designed for industrial, medical, and automotive systems requiring deterministic boot-time data access and long-term parameter retention without battery backup.

FAQ

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

The AT28C256-15TU-T supports a maximum page write size of 64 bytes per internal programming cycle. This is enabled by its internal 64-byte latch, which accepts sequential data within a 150 µs window (tBLC) after each WE high-to-low transition. All addresses written in a single page operation must reside on the same page, defined by A6–A14 bits; A0–A5 select individual bytes within that page. The AT28C256-15TU-T does not support larger block writes or sector erases.

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

No, the AT28C256-15TU-T operates solely from a 5 V ±10% supply (VCC = 4.5 V to 5.5 V) during standard read and write operations. A 12 V supply is required only for optional functions: accessing the 64-byte device identification area (applied to A9) and executing the software chip erase command. These 12 V operations are strictly controlled and isolated from normal 5 V logic; applying 12 V to any other pin will damage the AT28C256-15TU-T.

How does DATA Polling work on the AT28C256-15TU-T?

During a write cycle, reading the last-written address on the AT28C256-15TU-T returns the complement of the written data on I/O7. Once the internal programming completes, I/O7 outputs true data. This allows the host processor to poll I/O7 in a tight loop without fixed delays-detecting the transition from complement to true value signals write completion. The AT28C256-15TU-T supports this on any address, but polling the exact address just written yields fastest response.

Is the AT28C256-15TU-T pin-compatible with the older AT28C256-15PU?

No, the AT28C256-15TU-T (32-lead PLCC) is not pin-compatible with the AT28C256-15PU (28-lead PDIP). While both share identical logical functionality and JEDEC byte-wide signal definitions, their physical pin counts and layouts differ: the PLCC version includes two DC pins (1, 17) and additional address lines (A13, A14) routed to pins 30 and 2, whereas the PDIP places A13 and A14 on pins 26 and 1. PCB layout and socket design must be specific to the AT28C256-15TU-T's 32-pin PLCC footprint.

What endurance rating applies to the AT28C256-15TU-T?

The AT28C256-15TU-T carries a standard endurance rating of 10,000 write/erase cycles when operated with 10 ms page write timing. A variant marked "E" (e.g., AT28C256E-15TU-T) offers extended 100,000 cycles, but the base AT28C256-15TU-T-as indicated by absence of "E" in the marking-is rated for 10,000 cycles. This rating assumes operation within specified voltage (5 V ±10%), temperature (−40°C to +85°C), and timing (tWC ≤10 ms) limits per the DS20006386B datasheet.