Microchip Technology AT28C256E-15PU

Overview

AT28C256E-15PU from Microchip Technology is a military-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 serves as nonvolatile program/data storage in avionics control units, secure boot loaders, and radiation-tolerant instrumentation where byte- and page-level reprogrammability with hardware/software data protection is required.

For engineers reviewing the AT28C256E-15PU datasheet, AT28C256E-15PU pinout, AT28C256E-15PU application, or AT28C256E-15PU equivalent, key selection considerations include JEDEC byte-wide pin compatibility, DATA polling and toggle bit write completion detection, military temperature range (–55°C to +125°C), 100,000 write endurance, and software data protection enable/disable algorithms for secure field updates.

Technical Context

The AT28C256E-15PU implements a CMOS-based paged architecture with an internal 64-byte latch enabling simultaneous write of 1–64 bytes per cycle. Its dual-line chip enable (CE) and output enable (OE) control supports bus contention avoidance in shared-memory systems.

Write operations are validated via I/O7 DATA polling (complement-to-data during programming) or I/O6 toggle-bit detection, both usable at any point during tWC. Hardware protection includes VCC sense (<3.8 V inhibit), 5 ms power-on delay, noise filtering (<15 ns pulses ignored), and CE/OE/WE state-dependent write inhibition.

Key Specifications

Pinout & Package

AT28C256E-15PU is supplied in a 28-lead CERDIP (Ceramic Dual Inline Package) with 0.600" width, hermetically sealed per MIL-STD-1835 D-10 Config A. Pin 1 is index-marked; pins 14 (GND) and 28 (VCC) provide power distribution optimized for low-noise analog/digital co-location.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT28C256-15PU and DS2502-E48+, the AT28C256E-15PU uniquely delivers military temperature range, 100K endurance, and hardware/software write protection in a JEDEC-standard parallel package-making it the sole option for DO-254-compliant airborne systems requiring traceable reprogramming.

Availability

AT28C256E-15PU is available at Aetrix Electronics and suitable for avionics control units, secure boot loaders, and radiation-tolerant instrumentation requiring stable component supply across extended product lifecycles.

Supply support for AT28C256E-15PU 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 memory solutions with emphasis on reliability and long-term support.

The AT28C256E-15PU belongs to Microchip's military-grade parallel EEPROM product line, designed specifically for high-reliability applications in aerospace, defense, and industrial systems demanding guaranteed performance across extreme environmental conditions.

FAQ

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

The AT28C256E-15PU supports up to 64 bytes per page write operation. This is enabled by its internal 64-byte page register, which latches address and data simultaneously. All bytes in a given page write must reside within the same 64-byte boundary defined by address bits A6–A14, and each successive byte must be loaded within 150 µs of the prior one to avoid premature internal programming initiation. The AT28C256E-15PU does not support partial-page writes smaller than 1 byte or larger than 64 bytes.

How does hardware data protection function in the AT28C256E-15PU during power transitions?

Hardware data protection in the AT28C256E-15PU activates during power transitions via three mechanisms: (1) VCC sense circuitry inhibits writes when supply drops below 3.8 V, (2) a 5 ms internal power-on delay timer prevents writes until stable voltage is confirmed, and (3) noise filtering rejects input pulses shorter than 15 ns on CE or WE. These features ensure the AT28C256E-15PU remains immune to inadvertent writes during brown-out, hot-swap, or ESD-induced supply glitches-critical for MIL-STD-461F compliance in avionics platforms.

Can the AT28C256E-15PU be used as a direct replacement for standard SRAM in existing designs?

Yes, the AT28C256E-15PU can replace SRAM in read-dominant systems due to its 150 ns access time and identical JEDEC byte-wide pinout, but write operations require explicit timing control. Unlike SRAM, the AT28C256E-15PU needs CE/OE/WE handshaking and write-cycle detection (via DATA polling or toggle bit) before initiating subsequent accesses. Its 3–10 ms write latency means it cannot emulate true SRAM write behavior without firmware adaptation-but for configuration storage or infrequent updates, the AT28C256E-15PU eliminates battery backup and simplifies system design.

What is the purpose of the 64-byte device identification area in the AT28C256E-15PU?

The 64-byte device identification area (addresses 7FC0h–7FFFh) in the AT28C256E-15PU is electrically isolated and accessible only when A9 is raised to 12.0 V ±0.5 V. It enables permanent, tamper-resistant storage of unit-specific data such as serial numbers, calibration coefficients, manufacturing lot codes, and cryptographic keys. Because this region resides outside the main memory array and requires elevated voltage for access, it provides a secure anchor for traceability and anti-counterfeiting in defense logistics systems-ensuring the AT28C256E-15PU meets DFARS 252.211-7003 requirements for item unique identification.

Does the AT28C256E-15PU support chip erase functionality, and how is it initiated?

Yes, the AT28C256E-15PU supports full-chip erase via a 6-byte software command sequence executed with OE held high and CE/WE controlled per AC waveforms. The process requires applying 12.0 V ±0.5 V to A9 while issuing specific address/data patterns (detailed in Section 6.10 of DS20006344A). Chip erase resets all memory cells to FFh and clears the software data protection lock. Due to the high-voltage requirement and irreversible nature, chip erase is intended for factory reconditioning-not field use-and must be implemented with hardware interlocks to prevent accidental activation in deployed AT28C256E-15PU units.