Microchip Technology AT28C64E-25SC

Overview

AT28C64E-25SC from Atmel is a 64 Kbit (8K × 8) parallel EEPROM with JEDEC-standard byte-wide pinout, 250 ns read access time, 200 µs fast byte write cycle, and CMOS/TTL-compatible I/O - used in embedded system configuration storage, firmware parameter retention, and industrial controller nonvolatile data logging.

For engineers reviewing the AT28C64E-25SC datasheet, AT28C64E-25SC pinout, AT28C64E-25SC application, or AT28C64E-25SC equivalent, key selection considerations include its self-timed write architecture, RDY/BUSY and DATA polling status detection, 5V ±10% supply operation, industrial temperature range (–40°C to +85°C), and SOIC-28 package compatibility with legacy SRAM-based designs.

Technical Context

The AT28C64E-25SC implements a self-timed byte write cycle with internal address/data latching and automatic clear-before-write logic, eliminating external timing control. Its READY/BUSY open-drain output and I/O7 DATA polling provide deterministic write completion signaling without bus contention.

It operates as a drop-in replacement for static RAM in read/write cycles, supporting standard microprocessor control via CE/OE/WE signals. The device uses Atmel's nonvolatile floating-gate technology with error correction for 100,000 write endurance and 10-year data retention at 85°C.

Key Specifications

Pinout & Package

AT28C64E-25SC is packaged in a 28-lead, 0.300" wide plastic gull-wing small outline (SOIC) package per JEDEC MS-012, with 1.27 mm lead pitch and surface-mount compatibility.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT28C64B-25SC, the AT28C64E-25SC delivers 10× higher endurance and 5× faster writes - essential for dynamic field updates. Versus ST M48T02-25MH6, it offers simpler parallel integration, no battery dependency, and deterministic write signaling, but lacks RTC capability.

Availability

AT28C64E-25SC is available at Aetrix Electronics and suitable for industrial PLCs, medical diagnostic instruments, automotive body control modules, telecom line cards, and embedded data loggers requiring stable component supply across extended product lifecycles.

Supply support for AT28C64E-25SC 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

Atmel Corporation (now part of Microchip Technology) is a semiconductor manufacturer specializing in microcontrollers, nonvolatile memory, and secure authentication ICs for industrial, automotive, and IoT applications.

The AT28C64E-25SC belongs to Atmel's parallel EEPROM product line designed for direct replacement of SRAM in legacy 8-bit and 16-bit embedded systems, emphasizing pin compatibility, low-power operation, and robust write reliability in harsh environments.

FAQ

What is the maximum write endurance specification for the AT28C64E-25SC?

The AT28C64E-25SC is rated for 100,000 write/erase cycles - confirmed in the "Features" section and "DC Operating Range" table of the official Atmel datasheet (Rev. 0001H). This endurance applies across the full industrial temperature range (–40°C to +85°C) and is enabled by the "E" variant's enhanced floating-gate oxide process. Each cycle represents a full byte write to any address location within the 8K × 8 memory array.

Does the AT28C64E-25SC require an external high-voltage supply for programming or erase operations?

No, the AT28C64E-25SC performs all write and erase functions using only the standard 5 V ±10% supply (VCC). Unlike older EPROMs, it does not require 12 V or other external programming voltages. Chip Clear and Device Identification operations do use 12 V on A9 or OE, but these are optional features - standard byte writes operate entirely at 5 V with internal charge pumps.

How is write completion detected on the AT28C64E-25SC?

The AT28C64E-25SC provides two hardware-supported methods: (1) RDY/BUSY pin (Pin 1), an open-drain output pulled low during write and released upon completion; and (2) DATA Polling on I/O7, where reading the target address returns the complement of written data until completion, then returns true data. Both are documented in the "Device Operation" section and supported across all package variants including AT28C64E-25SC.

Is the AT28C64E-25SC pin-compatible with standard SRAM devices?

Yes - the AT28C64E-25SC uses a JEDEC-approved byte-wide pinout identical to common 8K × 8 SRAMs (e.g., 6264), including matching A0–A12, I/O0–I/O7, CE, OE, WE, and GND/VCC locations. This allows direct substitution in existing PCB layouts without redesign, provided timing margins accommodate the 250 ns read access and write latency behavior.

What package type and lead count does the AT28C64E-25SC use?

The AT28C64E-25SC uses a 28-lead, 0.300" wide plastic gull-wing small outline (SOIC) package, designated as "28S" in Atmel's ordering information. It conforms to JEDEC MS-012 standards, has 1.27 mm lead pitch, and is RoHS-compliant. Pin 1 is marked by a beveled corner and index notch, consistent with industry-standard SOIC orientation.