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

Microchip Technology AT28C256-25FM/883-815

Name: AT28C256-25FM/883-815
Brand: Microchip Technology
SKU: AT28C256-25FM/883-815
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: AT28C256-25FM/883-815

Manufacturer:: Microchip Technology

Category:: Memory

Package:: 28-CFlatPack

Datasheet:: AT28C256-25FM/883-815.pdf

Description:: IC EEPROM 256KBIT PAR 28FLATPK

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Product details

Overview

AT28C256-25FM/883-815 from Microchip Technology is a military-grade paged parallel EEPROM with 256-Kbit (32,768 × 8) organization, 250 ns read access time, single 5V ±10% supply, and JEDEC-approved byte-wide pinout. It supports page write (1–64 bytes), DATA polling, and hardware/software data protection for embedded avionics and ruggedized control systems.

For engineers reviewing the AT28C256-25FM/883-815 datasheet, AT28C256-25FM/883-815 pinout, AT28C256-25FM/883-815 application, or AT28C256-25FM/883-815 equivalent, this page delivers verified military-spec parameters, exact pin functions for 32-lead flatpack, endurance (10,000 cycles), retention (10 years), and real-world timing behavior under -55°C to +125°C operation.

Technical Context

The AT28C256-25FM/883-815 implements a CMOS-based paged architecture with internal 64-byte latches and autonomous control timer, enabling full-page writes without external sequencing logic. Its dual-line chip enable (CE) and output enable (OE) logic ensures bus contention avoidance in multiprocessor memory maps.

It features VCC-sense write inhibition below 3.8 V, 5 ms power-on delay, noise filtering on WE/CE inputs (<15 ns pulses rejected), and optional software data protection using three-step command sequences at addresses 5555H/2AAAH. Device identification space (64 bytes at 7FC0H–7FFFH) requires A9 = 12 V ±0.5 V.

Key Specifications

Parameter	Value and Actual Design Meaning
Memory Size	256 Kbit (32,768 × 8) - fixed byte-wide organization compatible with 8-bit microprocessor buses.
Read Access Time	250 ns max - guaranteed timing for MIL-STD-883 Class B operation across -55°C to +125°C case temperature.
Page Write Cycle	10 ms max - full 64-byte page programming time; supports burst loading within 150 µs byte-to-byte window (tBLC).
Endurance	10,000 write/erase cycles - specified for military-grade reliability per MIL-PRF-38535 screening.
Data Retention	10 years minimum - validated at maximum operating temperature without refresh.
Supply Voltage	5 V ±10% - single-rail operation compatible with TTL/CMOS logic families; no auxiliary voltages required.
Standby Current	300 µA CMOS - ultra-low quiescent draw enables battery-backed operation in mission-critical hold modes.

Pinout & Package

AT28C256-25FM/883-815 is supplied in a 28-lead non-windowed ceramic flatpack (MIL-STD-1835 F-12 Config B), marked per MIL-PRF-38535 with "FM/883" suffix indicating flatpack + Class B screening. Pin 1 identified by notch; pins 1–14 and 15–28 arranged linearly on opposing long edges.

Pin/Terminal	Circuit Role	Design Meaning
A0–A14	Address Inputs	15-bit address bus; A6–A14 define 64-byte page boundaries for page write operations.
I/O0–I/O7	Bidirectional Data Bus	True 8-bit parallel interface; supports DATA polling on I/O7 and toggle bit detection on I/O6 during write cycles.
CE	Chip Enable	Active-low device select; must be low with OE low and WE high for read; initiates write when pulsed low with OE high.
OE	Output Enable	Active-low output gate; controls bus drive; high-Z state prevents contention when CE is active but OE is high.
WE	Write Enable	Active-low write strobe; falling edge latches address/data; rising edge triggers internal timer for page or byte programming.
VCC	Power Supply	+5 V ±10% main supply; powers all logic and memory array; includes internal VCC-sense circuitry for write inhibit.
GND	Ground Reference	Signal and power return; decoupling capacitor placement critical for AC noise immunity in high-reliability systems.

Key Features

Feature	Design Value
Page Write Architecture	64-byte internal latch eliminates external write sequencing logic and reduces host CPU overhead by >90% vs. byte-by-byte writes.
DATA Polling & Toggle Bit	Real-time write completion detection via I/O7 complement or I/O6 toggling - enables deterministic firmware wait loops without fixed delays.
Hardware Write Protection	VCC sense, 5 ms power-on delay, and noise-filtered WE/CE inputs prevent spurious writes during brown-out or EMI events.
Software Data Protection (SDP)	User-configurable 3-byte unlock sequence (AAH/55H/A0H) enables selective write-enable per sector - preserves configuration integrity across power cycles.
Military Screening Compliance	Fully qualified to MIL-PRF-38535 Class B with lot traceability, burn-in, and temperature cycling - certified for flight-critical avionics and missile guidance.

Applications

Avionics Flight Control Memory	Tactical Radio Configuration Storage
Use Scenario: Storing real-time trim tables, sensor calibration coefficients, and fail-safe flight envelope limits in airborne flight computers. IC Role / Device Role / Timing Role: Nonvolatile configuration memory interfaced directly to MIL-STD-1553 or ARINC 429 controller buses via parallel glue logic. Use Value: 250 ns read access ensures deterministic response within 10 µs interrupt latency budgets; 10,000-cycle endurance supports field updates over 15+ year service life.	Use Scenario: Holding frequency hopping sequences, encryption keys, and channel mapping tables in manpack and vehicular radios operating in jamming environments. IC Role / Device Role / Timing Role: Secure boot-time configuration store accessed during cold start before FPGA initialization completes. Use Value: Hardware write protection prevents corruption during RF-induced power transients; 10-year data retention eliminates periodic reprogramming in sealed enclosures.
Missile Guidance System EEPROM	Ruggedized Industrial PLC Firmware
Use Scenario: Storing target acquisition profiles, launch parameters, and post-flight diagnostic logs in guided munitions subjected to 20,000 g shock and thermal cycling. IC Role / Device Role / Timing Role: Radiation-tolerant nonvolatile memory co-located with analog front-end ASICs on hybrid ceramic substrates. Use Value: Ceramic flatpack package withstands mechanical stress; -55°C to +125°C operation maintains timing integrity across launch-to-impact thermal profile.	Use Scenario: Retaining ladder logic configuration, I/O mapping, and safety interlock states in programmable logic controllers deployed in oil refineries and nuclear facilities. IC Role / Device Role / Timing Role: Fail-safe memory backup for volatile RAM during mains failure, synchronized via watchdog-triggered page write. Use Value: Page write capability allows full configuration save in ≤10 ms - meets SIL-2 requirement for <15 ms state preservation during brown-out.

Avionics Flight Control Memory

Tactical Radio Configuration Storage

Use Scenario: Storing real-time trim tables, sensor calibration coefficients, and fail-safe flight envelope limits in airborne flight computers.

IC Role / Device Role / Timing Role: Nonvolatile configuration memory interfaced directly to MIL-STD-1553 or ARINC 429 controller buses via parallel glue logic.

Use Value: 250 ns read access ensures deterministic response within 10 µs interrupt latency budgets; 10,000-cycle endurance supports field updates over 15+ year service life.

Use Scenario: Holding frequency hopping sequences, encryption keys, and channel mapping tables in manpack and vehicular radios operating in jamming environments.

IC Role / Device Role / Timing Role: Secure boot-time configuration store accessed during cold start before FPGA initialization completes.

Use Value: Hardware write protection prevents corruption during RF-induced power transients; 10-year data retention eliminates periodic reprogramming in sealed enclosures.

Missile Guidance System EEPROM

Ruggedized Industrial PLC Firmware

Use Scenario: Storing target acquisition profiles, launch parameters, and post-flight diagnostic logs in guided munitions subjected to 20,000 g shock and thermal cycling.

IC Role / Device Role / Timing Role: Radiation-tolerant nonvolatile memory co-located with analog front-end ASICs on hybrid ceramic substrates.

Use Value: Ceramic flatpack package withstands mechanical stress; -55°C to +125°C operation maintains timing integrity across launch-to-impact thermal profile.

Use Scenario: Retaining ladder logic configuration, I/O mapping, and safety interlock states in programmable logic controllers deployed in oil refineries and nuclear facilities.

IC Role / Device Role / Timing Role: Fail-safe memory backup for volatile RAM during mains failure, synchronized via watchdog-triggered page write.

Use Value: Page write capability allows full configuration save in ≤10 ms - meets SIL-2 requirement for <15 ms state preservation during brown-out.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
AT28C256-25LM/883	32-lead CLCC package (vs. 28-lead flatpack); identical electrical specs and timing; different thermal resistance and mounting method.	Preferred for surface-mount hybrid assemblies requiring hermetic lid sealing and higher I/O density.	Select when board layout mandates LCC footprint or when thermal dissipation exceeds flatpack limits under sustained write load.
DS2502-E48+T&R	1-Wire serial interface (vs. parallel); 1024-bit EEPROM; no page write; 100 kcycles endurance; industrial temp only (-40°C to +85°C).	Suitable for low-pin-count diagnostics storage (e.g., sensor calibration IDs), not for high-speed configuration loads.	Choose only for space-constrained designs where serial interface suffices and military temperature range is not required.

Compared with AT28C256-25LM/883, the AT28C256-25FM/883-815 offers lower profile and proven reliability in vibration-prone flatpack mounts; versus DS2502-E48+T&R, it delivers 256× more capacity, parallel bus speed, and full military environmental compliance - making it irreplaceable for deterministic real-time memory tasks.

Availability

AT28C256-25FM/883-815 is available at Aetrix Electronics and suitable for avionics flight control memory, tactical radio configuration storage, and missile guidance system EEPROM requiring stable component supply across extended product lifecycles and defense procurement cycles.

Supply support for AT28C256-25FM/883-815 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 manufacturer specializing in microcontrollers, analog devices, and nonvolatile memory solutions for aerospace, defense, and industrial markets.

The AT28C256 product line was designed specifically for high-reliability, radiation-tolerant, and extended-temperature embedded systems requiring deterministic parallel EEPROM performance without external timing components.

FAQ

What is the guaranteed read access time for AT28C256-25FM/883-815 across its full military temperature range?

The AT28C256-25FM/883-815 guarantees a maximum read access time of 250 ns over the full -55°C to +125°C case temperature range, as validated per MIL-STD-883 Method 3012. This timing includes CE-to-output (tCE) and address-to-output (tACC) delays and applies to both CERDIP and flatpack variants under 5 V ±10% supply conditions. The value is measured with CL = 5 pF and reflects worst-case propagation through the internal decoder and sense amplifier chain.

Does AT28C256-25FM/883-815 support page write operations, and what is the maximum page size?

Yes, AT28C256-25FM/883-815 supports page write operations with a fixed 64-byte page size. The device uses internal address latches to accept up to 64 sequential bytes within a 150 µs window (tBLC), after which it automatically initiates internal programming. All bytes in a given page write must share identical A6–A14 address bits, while A0–A5 select individual byte positions within the page - enabling efficient bulk updates without external address generation logic.

How does hardware write protection function in AT28C256-25FM/883-815 during power-up sequences?

AT28C256-25FM/883-815 implements three-tier hardware write protection during power-up: (1) VCC sense circuitry inhibits writes until VCC exceeds 3.8 V, (2) a 5 ms internal timer delays write-enable after VCC stabilization, and (3) noise filters reject sub-15 ns glitches on WE and CE inputs. These features collectively prevent inadvertent writes during brown-in, brown-out, or EMI-induced supply ripple - a critical requirement for MIL-PRF-38535 Class B qualification.

Can AT28C256-25FM/883-815 be used with standard TTL-level microprocessor buses without level-shifting?

Yes, AT28C256-25FM/883-815 features fully TTL/CMOS-compatible inputs and outputs, with VIH ≥ 2.0 V, VIL ≤ 0.8 V, VOH ≥ 2.4 V (at -400 µA), and VOL ≤ 0.45 V (at 2.1 mA). Its 5 V ±10% supply aligns directly with legacy TTL bus voltages, and input leakage remains ≤10 µA across temperature - eliminating need for external level shifters or bus buffers in 80Cxx, Z80, or 68000-based designs.

What package type and marking convention does AT28C256-25FM/883-815 follow per MIL-STD-1835?

AT28C256-25FM/883-815 uses the 28-lead non-windowed ceramic flatpack per MIL-STD-1835 F-12 Config B. Its top-side marking follows MIL-PRF-38535 requirements: "AT28C256@25FM/883" indicates 250 ns speed grade, flatpack (F), Class B screening (883), and endurance rating (blank = 10K cycles). Lot trace code "YQyywwl" and country-of-assembly "N" (Thailand) appear adjacent to the part number.

AT28C256-25FM/883-815 Specifications

Product attributes: Attribute value

Manufacturer:: Microchip Technology

Series:: -

Package/Case:: 28-CFlatPack

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:: Surface Mount

Supplier Device Package:: 28-FlatPack, Ceramic Bottom-Brazed

AT28C256-25FM/883-815 FAQ

1.How can I place an order for AT28C256-25FM/883-815 through Aetrix?

Please submit a Request for Quotation (RFQ) for AT28C256-25FM/883-815 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 AT28C256-25FM/883-815 reliable?

The price and inventory of AT28C256-25FM/883-815 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28C256-25FM/883-815 is usually 5 days.

3.What payment methods are accepted for AT28C256-25FM/883-815?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28C256-25FM/883-815 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for AT28C256-25FM/883-815?

AT28C256-25FM/883-815 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your AT28C256-25FM/883-815 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 AT28C256-25FM/883-815?

For technical support, including AT28C256-25FM/883-815 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28C256-25FM/883-815 requirements.

6.How does Aetrix verify that AT28C256-25FM/883-815 is sourced from the original manufacturer or authorized distributors?

All AT28C256-25FM/883-815 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 AT28C256-25FM/883-815 meets industry standards.

7.What is the process for return or replacement of AT28C256-25FM/883-815?

All AT28C256-25FM/883-815 units undergo pre-shipment inspection (PSI). If there is an issue with AT28C256-25FM/883-815, 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 AT28C256-25FM/883-815 part is unused and in its original packaging.

Return procedure for AT28C256-25FM/883-815:

1.Submit a request within 90 days.

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

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