Microchip Technology AT28C256E-15SU

Overview

AT28C256E-15SU from Microchip Technology is an industrial-grade 256-Kbit paged parallel EEPROM organized as 32,768 × 8, featuring 150 ns read access time, 64-byte page write capability, and single 5V ±10% supply operation. It serves as nonvolatile program/data storage in microcontroller-based systems requiring byte- or page-level reprogrammability without external high-voltage circuitry.

For engineers reviewing the AT28C256E-15SU datasheet, AT28C256E-15SU pinout, AT28C256E-15SU application, or AT28C256E-15SU equivalent, key selection criteria include JEDEC-standard 28-pin SOIC package compatibility, DATA polling/Toggle Bit end-of-write detection, hardware/software data protection, and industrial temperature range (–40°C to +85°C) support.

Technical Context

The AT28C256E-15SU implements a CMOS-based paged architecture with internal 64-byte latches and autonomous control timer for page writes. Its dual-line chip enable (CE) and output enable (OE) logic enables bus contention avoidance in shared-memory systems.

It supports three distinct write modes: byte write, page write (1–64 bytes within same A6–A14 page), and optional software-enabled chip erase. End-of-write status is confirmed via I/O7 DATA polling or I/O6 Toggle Bit behavior-both usable at any point during tWC (≤10 ms).

Key Specifications

Pinout & Package

AT28C256E-15SU is supplied in a 28-lead Small Outline Integrated Circuit (SOIC) package with JEDEC-standard byte-wide pinout. Pin 1 is marked by a beveled corner or notch; device is lead-free and RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT28C256-15SU, the AT28C256E-15SU offers doubled endurance (100K vs. 10K cycles) with identical timing, package, and interface-making it ideal for frequently updated configurations. The ST M28W256F requires board-level changes due to voltage and programming voltage differences, limiting direct substitution.

Availability

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

Supply support for AT28C256E-15SU 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 U.S.-based semiconductor company specializing in microcontrollers, analog devices, and nonvolatile memory solutions, with ISO 9001-certified manufacturing and global distribution.

The AT28C256E-15SU belongs to Microchip's legacy parallel EEPROM product line, engineered for robustness in industrial and automotive applications where reliability, long-term data retention, and simple 5V interface are critical.

FAQ

What does the 'E' in AT28C256E-15SU signify?

The 'E' suffix in AT28C256E-15SU indicates extended endurance: 100,000 write/erase cycles versus the standard 10,000 cycles of the base AT28C256-15SU. All other electrical, timing, and mechanical specifications-including 150 ns read access, 10 ms max page write, and 28-pin SOIC packaging-are identical between the two variants. This makes AT28C256E-15SU suitable for applications requiring frequent field updates without compromising longevity.

Does AT28C256E-15SU require a high-voltage programming supply?

No, AT28C256E-15SU operates from a single 5V ±10% supply for both read and write operations. It incorporates internal charge pumps and VCC-sense circuitry that automatically inhibit writes below ~3.8 V and enforce a 5 ms power-on delay-eliminating the need for external VPP (12 V) or complex voltage regulation. This simplifies PCB design and reduces BOM cost compared to older EEPROM families requiring dual-supply support.

How is write completion detected on AT28C256E-15SU?

AT28C256E-15SU supports two hardware-confirmed methods: DATA polling on I/O7 (complement of last written byte appears until write completes) and Toggle Bit monitoring on I/O6 (toggles between 0/1 during write, then stabilizes). Both methods are usable at any time during the write cycle and require no additional timing components. These features allow deterministic, interrupt-driven write handling without fixed delays or external status lines.

Can AT28C256E-15SU be used in place of AT28C256-15SU without board changes?

Yes, AT28C256E-15SU is a pin-compatible, functionally identical drop-in replacement for AT28C256-15SU in 28-pin SOIC packaging. The only difference is the guaranteed 100,000-cycle endurance rating (vs. 10,000), with identical DC/AC characteristics, timing parameters, and software data protection algorithms. No layout, firmware, or schematic modifications are needed-only the bill of materials requires updating to reflect the 'E' variant.

What is the purpose of the extra 64 bytes of EEPROM in AT28C256E-15SU?

The AT28C256E-15SU includes 64 bytes of dedicated identification memory (addresses 7FC0H–7FFFH), accessible by raising A9 to 12.0 V ±0.5 V. This area is intended for permanent device serialization, calibration traceability, or manufacturing lot tracking-separate from main array usage. It supports the same read/write protocols as the primary memory but is electrically isolated to prevent accidental overwrite during normal operation.