Microchip Technology AT28C256-15SU-T

Overview

AT28C256-15SU-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 supports hardware/software data protection and DATA Polling for end-of-write detection, and is used in firmware storage, configuration retention, and boot code storage in embedded controllers.

For engineers reviewing the AT28C256-15SU-T datasheet, AT28C256-15SU-T pinout, AT28C256-15SU-T application, or AT28C256-15SU-T equivalent, key selection considerations include JEDEC byte-wide pinout compatibility, 64-byte page write capability, industrial temperature range (–40°C to +85°C), CMOS/TTL I/O compatibility, and software data protection enable/disable algorithms.

Technical Context

The AT28C256-15SU-T implements a paged architecture with an internal 64-byte latch that enables simultaneous loading of up to 64 bytes per write cycle. Its dual-line control logic (CE/OE/WE) allows SRAM-like read access and flexible bus contention management.

Write completion is verified via DATA Polling on I/O7 (complement-to-data during write, true data upon completion) or Toggle Bit behavior on I/O6. Hardware protection includes VCC sense (<3.8 V inhibits writes), 5 ms power-on delay, and noise filtering on WE/CE inputs.

Key Specifications

Pinout & Package

AT28C256-15SU-T is supplied in a 28-lead SOIC package with JEDEC-standard byte-wide pinout. The "SU" suffix denotes SOIC narrow (300 mil) body; "-15" indicates 150 ns access time; "T" denotes tape-and-reel packaging.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT28C256-15PU and AT28C256-15JI, the AT28C256-15SU-T offers optimal balance of automated SMT manufacturability, board space efficiency, and JEDEC-compliant pinout-making it the preferred choice for volume production of industrial and automotive control modules requiring 5V parallel EEPROM.

Availability

AT28C256-15SU-T is available at Aetrix Electronics and suitable for industrial PLC configuration storage, legacy embedded boot memory, automotive body control module identity, and test equipment calibration data vault applications requiring stable component supply and long-term lifecycle support.

Supply support for AT28C256-15SU-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 provider of microcontrollers, analog devices, and memory solutions, with expertise in nonvolatile memory design and industrial-grade qualification.

The AT28C256 product line delivers paged parallel EEPROMs optimized for firmware storage, configuration retention, and boot code execution in 5V embedded systems where SRAM-like interface simplicity and long-term data integrity are essential.

FAQ

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

The AT28C256-15SU-T supports a maximum page write size of 64 bytes. This is enabled by its internal 64-byte page register, which latches address and data during a single write initiation. Each successive byte must be loaded within 150 µs of the previous one (tBLC), and all addresses must reside on the same page defined by A6–A14. The AT28C256-15SU-T does not support larger page sizes or burst writes beyond this limit.

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

No, the AT28C256-15SU-T operates from a single 5V ±10% supply and does not require external high-voltage programming. All write operations-including byte, page, and chip erase-are executed using standard 5V logic levels. The optional 12V programming for the 64-byte ID sector (A9 = 12V) is strictly limited to that dedicated region and is not needed for main array writes. The AT28C256-15SU-T integrates internal charge pumps and voltage regulation to eliminate external HV components.

How is write completion detected on the AT28C256-15SU-T?

Write completion on the AT28C256-15SU-T is detected using either DATA Polling on I/O7 or the Toggle Bit on I/O6. During a write, reading the last written address returns the complement of the data on I/O7; when true data appears, the write is complete. Alternatively, I/O6 toggles between 0 and 1 during the write and stabilizes upon completion. Both methods are supported simultaneously and require no additional hardware. The AT28C256-15SU-T guarantees these mechanisms function across its full industrial temperature range.

Is the AT28C256-15SU-T pin-compatible with standard 27C256 EPROMs?

Yes, the AT28C256-15SU-T uses a JEDEC-approved byte-wide pinout identical to the 27C256 EPROM, including matching A0–A14, I/O0–I/O7, CE, OE, WE, VCC, and GND assignments. However, unlike the 27C256, the AT28C256-15SU-T requires no UV erasure or external programming voltage and supports in-system rewrites. The AT28C256-15SU-T can serve as a functional and pin-compatible drop-in replacement in most 27C256-based designs, provided the host controller supports the WE-controlled write protocol.

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

The AT28C256-15SU-T carries a standard endurance rating of 10,000 write cycles, as indicated by the absence of an "E" or "F" suffix in its marking (per DS20006386B-page 21). The "F" variant (e.g., AT28C256F) offers faster 3 ms page writes but same 10K endurance; the "E" variant provides extended 100,000 cycles at 10 ms write time. The AT28C256-15SU-T's endurance is validated per JEDEC standards and applies to both byte and page write operations across its full industrial temperature range.