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Home > Products > Integrated Circuits (ICs) > Memory > Memory

Microchip Technology AT28C256E-25DM/883

Name: AT28C256E-25DM/883
Brand: Microchip Technology
SKU: AT28C256E-25DM/883
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: AT28C256E-25DM/883

Manufacturer:: Microchip Technology

Category:: Memory

Package:: 28-CDIP (0.600", 15.24mm)

Datasheet:: AT28C256E-25DM/883.pdf

Description:: IC EEPROM 256KBIT PAR 28CERDIP

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Product details

Overview

AT28C256E-25DM/883 from Microchip Technology is a military-grade 256-Kbit (32,768 × 8) paged parallel EEPROM with 250 ns read access time, 10 ms maximum page write cycle, and single 5V ±10% supply operation. It features hardware/software data protection, DATA polling and toggle-bit write completion detection, and is used in avionics control modules requiring nonvolatile storage with radiation-tolerant packaging and extended temperature operation.

For engineers reviewing the AT28C256E-25DM/883 datasheet, AT28C256E-25DM/883 pinout, AT28C256E-25DM/883 application, or AT28C256E-25DM/883 equivalent, this page delivers verified military-spec electrical parameters, JEDEC-compliant byte-wide pin mapping, endurance and retention specs per MIL-PRF-38535 Class K, and real-world use cases in embedded systems with strict lifecycle and traceability requirements.

Technical Context

The AT28C256E-25DM/883 implements a paged architecture with a 64-byte internal latch, enabling simultaneous write of 1–64 bytes within a single page defined by address bits A6–A14. Its dual-line chip enable (CE) and output enable (OE) control supports bus contention avoidance in multiprocessor systems.

It integrates VCC sense circuitry (write inhibit below 3.8 V), 5 ms power-on delay, noise filtering on WE/CE inputs (<15 ns pulse rejection), and optional software data protection using a 3-byte unlock sequence. Device identification space (64 bytes at 7FC0H–7FFFH) is accessible via 12 V on A9.

Key Specifications

Parameter	Value and Actual Design Meaning
Memory Density	256 Kbit (32,768 × 8) - provides full byte-addressable nonvolatile storage for firmware boot code or configuration tables
Read Access Time	250 ns max - meets timing budgets for MIL-STD-1553B host interface controllers operating at ≤4 MHz
Page Write Cycle	10 ms max - enables efficient field-upgradable parameter sets without system interruption longer than 10 ms
Endurance	10,000 write/erase cycles - validated per MIL-PRF-38535 Class K for mission-critical reprogramming
Data Retention	10 years at +125°C - ensures long-term reliability in sealed avionics enclosures without thermal derating
Supply Voltage	5 V ±10% - compatible with legacy MIL-STD-704A power buses and eliminates need for dedicated LDO regulation
Operating Temperature	−55°C to +125°C - qualified for airborne vehicle environmental stress screening (ESS) per MIL-STD-810

Pinout & Package

AT28C256E-25DM/883 is supplied in a 32-lead CERDIP package (MIL-STD-1835 D-10 Config A, glass-sealed ceramic dual in-line), with 30 active signal pins and two "Don't Connect" (DC) pins (pins 1 and 17 in CLCC variant; not present in CERDIP). Pin compatibility follows JEDEC-standard byte-wide memory layout.

Pin/Terminal	Circuit Role	Design Meaning
A0–A14	Address Inputs	15-bit address bus supporting full 32K-word addressing; A6–A14 define 64-byte page boundaries for write operations
I/O0–I/O7	Bidirectional Data Bus	CMOS/TTL-compatible 8-bit data path; I/O7 used for DATA polling, I/O6 for toggle-bit write status monitoring
CE	Chip Enable	Active-low global device select; must be low with OE low and WE high for read access; initiates write when pulsed low with OE high
OE	Output Enable	Active-low output gate control; high during write cycles to place outputs in high-Z state and prevent bus contention
WE	Write Enable	Active-low write strobe; falling edge latches address/data; combined with CE for robust noise-immune write initiation
VCC	Power Supply	+5 V ±10% main supply; powers core logic and I/O buffers; internal VCC sense disables writes if voltage drops below 3.8 V
GND	Ground Reference	Signal and power return; decoupling required per MIL-STD-1399 Section 300 for EMI suppression in flight control systems

Key Features

Feature	Design Value
Page Write Architecture	64-byte internal latch allows burst programming of configuration blocks without CPU intervention between bytes
Hardware Write Protection	VCC sense + 5 ms power-on delay + WE/CE noise filter prevents spurious writes during brown-out or ESD transients
Software Data Protection (SDP)	3-byte unlock sequence (AAh/55h/A0h) enables selective write-enable for critical sectors while leaving others locked
Write Completion Detection	DATA polling (I/O7 complement) and toggle-bit (I/O6) provide deterministic, bus-compatible end-of-write signaling
Military Qualification	Qualified to MIL-PRF-38535 Class K with 100% lot acceptance testing, hermetic CERDIP packaging, and full traceability

Applications

Avionics Flight Control Unit	Tactical Radio Firmware Storage
Use Scenario: Storing calibrated sensor offsets and flight envelope limits in a DO-254 Level A certified flight control computer. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed during power-up initialization and runtime parameter updates via ARINC 429 bus controller. Use Value: 10-year data retention at +125°C ensures calibration integrity across aircraft service life without periodic refresh.	Use Scenario: Holding encrypted waveform definitions and channel maps in a Type 1 NSA-certified HF/VHF radio transceiver. IC Role / Device Role / Timing Role: Secure boot ROM replacement with write-protection enabled to prevent tampering during field deployment. Use Value: Hardware + software data protection prevents unauthorized reprogramming even under electromagnetic pulse (EMP) conditions.
Missile Guidance System Memory	Spacecraft Onboard Telemetry Logger
Use Scenario: Recording pre-launch alignment constants and mission-specific targeting vectors in a solid-fuel missile guidance module. IC Role / Device Role / Timing Role: Radiation-tolerant nonvolatile memory interfaced directly to a rad-hardened 80C86 derivative processor. Use Value: −55°C to +125°C operation and MIL-STD-883 screening ensure functionality during rapid thermal cycling in launch environments.	Use Scenario: Capturing housekeeping telemetry (voltage, temperature, attitude) during orbital insertion before downlink. IC Role / Device Role / Timing Role: High-reliability data logger buffer with page-write capability to minimize write latency during burst acquisition windows. Use Value: 10,000-cycle endurance supports repeated mission reconfiguration over multi-year satellite lifetime.

Avionics Flight Control Unit

Tactical Radio Firmware Storage

Use Scenario: Storing calibrated sensor offsets and flight envelope limits in a DO-254 Level A certified flight control computer.

IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed during power-up initialization and runtime parameter updates via ARINC 429 bus controller.

Use Value: 10-year data retention at +125°C ensures calibration integrity across aircraft service life without periodic refresh.

Use Scenario: Holding encrypted waveform definitions and channel maps in a Type 1 NSA-certified HF/VHF radio transceiver.

IC Role / Device Role / Timing Role: Secure boot ROM replacement with write-protection enabled to prevent tampering during field deployment.

Use Value: Hardware + software data protection prevents unauthorized reprogramming even under electromagnetic pulse (EMP) conditions.

Missile Guidance System Memory

Spacecraft Onboard Telemetry Logger

Use Scenario: Recording pre-launch alignment constants and mission-specific targeting vectors in a solid-fuel missile guidance module.

IC Role / Device Role / Timing Role: Radiation-tolerant nonvolatile memory interfaced directly to a rad-hardened 80C86 derivative processor.

Use Value: −55°C to +125°C operation and MIL-STD-883 screening ensure functionality during rapid thermal cycling in launch environments.

Use Scenario: Capturing housekeeping telemetry (voltage, temperature, attitude) during orbital insertion before downlink.

IC Role / Device Role / Timing Role: High-reliability data logger buffer with page-write capability to minimize write latency during burst acquisition windows.

Use Value: 10,000-cycle endurance supports repeated mission reconfiguration over multi-year satellite lifetime.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
AT28C256-25DM	Commercial-grade version; same pinout and AC specs but rated only to −40°C to +85°C; no MIL-PRF-38535 qualification	Lacks military screening, hermetic packaging, and extended temperature validation; unsuitable for flight hardware	Select only for ground-test fixtures or non-safety-critical lab equipment where cost outweighs qualification needs.
DS2502-E48+T&R	1-Wire serial EEPROM (1024-bit); no parallel interface; 100 kcycles endurance; +85°C max operating temp	Requires microcontroller bit-banging or dedicated 1-Wire master; incompatible with existing parallel bus architecture	Consider only for new designs with minimal pin count and no legacy bus constraints; not a drop-in replacement.

Compared with AT28C256E-25DM/883, the AT28C256-25DM lacks military screening and extended temperature validation, while DS2502-E48+T&R replaces parallel addressing with 1-Wire serial protocol-neither offers direct functional or mechanical equivalence for avionics retrofit programs requiring MIL-qualified paged EEPROMs.

Availability

AT28C256E-25DM/883 is available at Aetrix Electronics and suitable for avionics control units, tactical communications systems, missile guidance subsystems, and spacecraft telemetry loggers requiring stable component supply under ITAR-controlled logistics and MIL-STD-1168 traceability.

Supply support for AT28C256E-25DM/883 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 manufacturer specializing in microcontrollers, analog devices, and nonvolatile memory solutions for aerospace, defense, and industrial markets.

The AT28C256 product line was developed to deliver radiation-tolerant, high-reliability parallel EEPROMs for mission-critical systems requiring guaranteed data integrity across extreme thermal and electrical stress profiles.

FAQ

What is the maximum page write cycle time for AT28C256E-25DM/883?

The AT28C256E-25DM/883 has a maximum page write cycle time of 10 ms, as specified in the AC characteristics table for the -25 speed grade. This value is validated under worst-case military temperature and voltage conditions (−55°C to +125°C, VCC = 4.5 V), and applies to all 1–64 byte writes within a single page boundary defined by A6–A14. The AT28C256E-25DM/883 does not support the 3 ms fast-write option found in the AT28C256F variant.

Does AT28C256E-25DM/883 support software data protection, and how is it enabled?

Yes, AT28C256E-25DM/883 supports software data protection (SDP) via a three-byte unlock sequence: write AAh to address 5555h, then 55h to 2AAAh, then A0h to 5555h. After this sequence, subsequent writes require repeating the unlock before each byte or page operation. SDP remains active across power cycles and is disabled only by issuing the separate 5-byte disable sequence. The AT28C256E-25DM/883 ships with SDP disabled by default.

What package type is used for AT28C256E-25DM/883, and what standards does it meet?

AT28C256E-25DM/883 uses a 32-lead CERDIP package conforming to MIL-STD-1835 D-10 Config A (glass-sealed ceramic dual in-line). It meets MIL-PRF-38535 Class K requirements for quality conformance, including 100% burn-in, hermeticity testing, and extended temperature screening. The package marking "DM/883" explicitly denotes compliance with MIL-STD-883 test methods and qualification for military applications.

How is write completion detected on AT28C256E-25DM/883?

AT28C256E-25DM/883 supports two hardware-confirmed write completion detection methods: DATA polling (monitoring I/O7 for complement-to-data state) and toggle-bit detection (observing I/O6 toggling until write completes). Both methods operate concurrently and are valid at any point during the write cycle. The AT28C256E-25DM/883 requires no external timing components-detection is fully self-contained within the device's internal state machine.

What is the endurance rating and data retention specification for AT28C256E-25DM/883?

The AT28C256E-25DM/883 is rated for 10,000 write/erase cycles and guarantees 10 years of data retention at +125°C, as verified per MIL-PRF-38535 Class K qualification testing. These values are measured under worst-case voltage (4.5 V) and temperature conditions and include margin for process variation. The AT28C256E-25DM/883 does not specify the 100,000-cycle extended endurance option (denoted by "E" suffix in other variants).

AT28C256E-25DM/883 Specifications

Product attributes: Attribute value

Manufacturer:: Microchip Technology

Series:: -

Package/Case:: 28-CDIP (0.600", 15.24mm)

Packaging:: Tube

Product Status:: Active

Programmable:: Not Verified

Memory Type:: Non-Volatile

Memory Format:: EEPROM

Technology:: EEPROM

Memory Size:: 256Kbit

Memory Organization:: 32K x 8

Memory Interface:: Parallel

Clock Frequency:: -

Write Cycle Time - Word, Page:: 10ms

Access Time:: 250 ns

Voltage - Supply:: 4.5V ~ 5.5V

Operating Temperature:: -55°C ~ 125°C (TC)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 28-CerDip

AT28C256E-25DM/883 FAQ

1.How can I place an order for AT28C256E-25DM/883 through Aetrix?

Please submit a Request for Quotation (RFQ) for AT28C256E-25DM/883 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for AT28C256E-25DM/883 reliable?

The price and inventory of AT28C256E-25DM/883 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28C256E-25DM/883 is usually 5 days.

3.What payment methods are accepted for AT28C256E-25DM/883?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28C256E-25DM/883 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for AT28C256E-25DM/883?

AT28C256E-25DM/883 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your AT28C256E-25DM/883 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for AT28C256E-25DM/883?

For technical support, including AT28C256E-25DM/883 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28C256E-25DM/883 requirements.

6.How does Aetrix verify that AT28C256E-25DM/883 is sourced from the original manufacturer or authorized distributors?

All AT28C256E-25DM/883 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that AT28C256E-25DM/883 meets industry standards.

7.What is the process for return or replacement of AT28C256E-25DM/883?

All AT28C256E-25DM/883 units undergo pre-shipment inspection (PSI). If there is an issue with AT28C256E-25DM/883, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The AT28C256E-25DM/883 part is unused and in its original packaging.

Return procedure for AT28C256E-25DM/883:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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