Microchip Technology AT28C256E-15SU-T

Overview

AT28C256E-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, 10 ms maximum page write cycle time, 100,000 write endurance cycles, and single 5V ±10% supply operation. It supports hardware and software data protection and is used in embedded systems requiring nonvolatile storage for firmware configuration, calibration data, or boot code retention.

For engineers reviewing the AT28C256E-15SU-T datasheet, AT28C256E-15SU-T pinout, AT28C256E-15SU-T application, or AT28C256E-15SU-T equivalent, this page delivers verified electrical characteristics, JEDEC-compliant byte-wide pinout mapping, page-write timing constraints, DATA Polling and Toggle Bit end-of-write detection methods, and industrial temperature range (-40°C to +85°C) validation.

Technical Context

The AT28C256E-15SU-T implements a CMOS-based paged EEPROM architecture with a 64-byte internal page register, enabling simultaneous latching of up to 64 bytes before autonomous internal programming. Its dual-line chip enable (CE) and output enable (OE) control allows flexible bus contention management during read operations.

Write execution uses an internal control timer with automatic self-timing; end-of-write status is confirmed via I/O7 DATA Polling (complement-to-data behavior) or I/O6 Toggle Bit toggling. Software Data Protection (SDP) is implemented via a 3-byte command sequence at fixed addresses (5555H/2AAAH), and hardware protection includes VCC sense (<3.8V inhibit), 5 ms power-on delay, and noise filtering on WE/CE inputs.

Key Specifications

Pinout & Package

AT28C256E-15SU-T is supplied in a 28-lead SOIC package (JEDEC MS-012AC) with 600-mil body width and gull-wing leads. Pin 1 is marked by a beveled corner or laser dot per Microchip specification DS20006386B.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT28C256E-15SU-T, AT28C256-15PU trades industrial-grade endurance and SOIC manufacturability for through-hole convenience, while M95256-DW replaces parallel simplicity with serial density and higher endurance at the cost of interface complexity and deterministic timing control.

Availability

AT28C256E-15SU-T is available at Aetrix Electronics and suitable for industrial PLCs, medical diagnostics, automotive body control modules, and automated test equipment requiring stable component supply across multi-year production lifecycles.

Supply support for AT28C256E-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 semiconductor company specializing in microcontrollers, analog components, and nonvolatile memory solutions, with ISO 9001-certified manufacturing and broad industrial qualification coverage.

The AT28C256 product line delivers high-reliability parallel EEPROMs for legacy bus architectures in industrial, medical, and automotive applications where pin-compatible EPROM replacement and deterministic write timing are essential.

FAQ

What is the maximum page write size supported by the AT28C256E-15SU-T?

The AT28C256E-15SU-T supports a maximum page write size of 64 bytes. This is enabled by its internal 64-byte page register, which latches sequential data within 150 µs of the prior byte's WE transition. All bytes in a single page write must reside on the same page, defined by identical A6–A14 address bits during each WE pulse. The AT28C256E-15SU-T does not support partial-page writes smaller than 1 byte or larger than 64 bytes.

How does DATA Polling work on the AT28C256E-15SU-T during a write operation?

During a write cycle, reading the last written address on the AT28C256E-15SU-T returns the complement of the written data on I/O7 until completion. Once the internal programming finishes, true data appears on all I/O lines including I/O7. This allows the host MCU to poll I/O7 in a tight loop without timers or interrupts. The AT28C256E-15SU-T guarantees this behavior across its full industrial temperature range and voltage tolerance.

Is the AT28C256E-15SU-T pin-compatible with standard 27C256 EPROMs?

Yes, the AT28C256E-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. Pins 12 and 26 are NC on both devices. This enables direct socket replacement in existing designs without PCB modification, provided the system accommodates the AT28C256E-15SU-T's write-enable timing and software protection requirements.

What write endurance rating does the 'E' suffix indicate in AT28C256E-15SU-T?

The 'E' suffix in AT28C256E-15SU-T denotes Extended endurance: 100,000 write/erase cycles minimum, validated per Microchip DS20006386B. This contrasts with the base AT28C256 (no suffix) rated for 10,000 cycles and the 'F' variant rated for 3 ms fast write but only 10,000 cycles. The AT28C256E-15SU-T maintains this 100K-cycle rating across its full -40°C to +85°C operating range.

Does the AT28C256E-15SU-T require a 12V supply for any operation?

No, the AT28C256E-15SU-T operates exclusively from a single 5V ±10% supply (VCC). A 12V supply is only required for optional Chip Erase mode (applied to A9) or Device Identification memory programming-functions not needed for standard read/write operation. All normal read, byte write, and page write functions execute at 5V. The AT28C256E-15SU-T includes internal VCC sensing that inhibits writes below 3.8V, eliminating risk of corruption during 5V rail instability.