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Microchip Technology AT28C256-20LM/883-815

Name: AT28C256-20LM/883-815
Brand: Microchip Technology
SKU: AT28C256-20LM/883-815
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: AT28C256-20LM/883-815

Manufacturer:: Microchip Technology

Category:: Memory

Package:: 32-CLCC

Datasheet:: AT28C256-20LM/883-815.pdf

Description:: IC EEPROM 256KBIT PARALLEL 32LCC

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Product details

Overview

AT28C256-20LM/883-815 from Microchip Technology is a military-grade 256-Kbit (32,768 × 8) paged parallel EEPROM with 200 ns read access time, JEDEC-standard byte-wide pinout, and single 5V ±10% supply operation. It supports page write cycles of up to 64 bytes with 10 ms maximum duration, delivers 50 mA active current and 300 µA CMOS standby current, and is qualified per MIL-PRF-38535 Class B for use in avionics data logging and secure firmware storage.

For engineers reviewing the AT28C256-20LM/883-815 datasheet, AT28C256-20LM/883-815 pinout, AT28C256-20LM/883-815 application, or AT28C256-20LM/883-815 equivalent, this page provides verified military-spec timing, endurance (10,000 cycles), data retention (10 years), hardware/software write protection, and CLCC-32 package details - all confirmed from Microchip DS20006344A.

Technical Context

The AT28C256-20LM/883-815 implements a paged architecture with an internal 64-byte latch and autonomous control timer, enabling simultaneous write of 1–64 bytes without external sequencing logic. Its dual-line chip enable (CE) and output enable (OE) control allows bus contention avoidance in shared-memory systems.

It features DATA Polling on I/O7 and Toggle Bit detection on I/O6 for real-time write completion monitoring, plus VCC sense (3.8 V threshold), 5 ms power-on delay, and noise filtering (<15 ns pulse rejection) for robust hardware write inhibition. Software Data Protection uses a 3-byte command sequence (AAh/55h/A0h) to enable/disable write lock.

Key Specifications

Parameter	Value and Actual Design Meaning
Memory Size	256 Kbit (32,768 × 8) - directly replaces SRAM in legacy 8-bit microcontroller systems without address decoding changes.
Read Access Time	200 ns max - meets timing requirements for 5 MHz bus operation with adequate setup/hold margins.
Page Write Cycle Time	10 ms max - enables burst programming of configuration tables while maintaining deterministic system response.
Endurance	10,000 write/erase cycles - validated for field-updatable mission-critical parameters in aerospace telemetry units.
Data Retention	10 years at +125°C - ensures firmware integrity over full lifecycle in sealed military enclosures.
Supply Voltage	5 V ±10% - compatible with legacy TTL/CMOS logic families without level-shifting circuitry.
Operating Temperature	−55°C to +125°C - qualified per MIL-PRF-38535 Class B for extended-range embedded control.

Pinout & Package

AT28C256-20LM/883-815 is supplied in a 32-pad Ceramic Leadless Chip Carrier (CLCC) package per MIL-STD-1835 C-12, with pins 1 and 17 designated "Don't Connect" per Microchip DS20006344A-page 4. The package is hermetically sealed, lead-free, and rated for high-reliability military applications.

Pin/Terminal	Circuit Role	Design Meaning
A0–A14	Address Inputs	15-bit address bus supporting full 32K-word addressing; A6–A14 define page boundaries for 64-byte writes.
I/O0–I/O7	Bidirectional Data Bus	CMOS/TTL-compatible 8-bit parallel interface; I/O7 used for DATA Polling, I/O6 for Toggle Bit status feedback.
CE	Chip Enable	Active-low selection signal; must be low with OE low and WE high for read access; initiates write when pulsed low.
OE	Output Enable	Active-low output gate; high-Z state prevents bus contention during write cycles or standby mode.
WE	Write Enable	Active-low write strobe; falling edge latches address/data; combined with CE controls byte vs. page write mode.
VCC	Power Supply	+5 V ±10% main supply; internal VCC sense disables writes below 3.8 V to prevent corruption during brownout.
GND	Ground Reference	Signal and power ground reference; decoupling capacitor required within 10 mm of VCC pin per layout guidelines.
DC (pins 1, 17)	Don't Connect	No internal connection; must remain unconnected per Microchip specification to avoid parasitic coupling or ESD paths.

Key Features

Feature	Design Value
JEDEC-standard byte-wide pinout	Direct drop-in replacement for industry-standard 27C256 EPROMs and 62256 SRAMs in existing PCB layouts.
Hardware write protection	VCC sense, 5 ms power-on delay, and <15 ns noise filtering eliminate need for external reset supervisors or RC timers.
Software Data Protection (SDP)	3-byte unlock sequence (AAh/55h/A0h) prevents accidental writes without modifying host firmware logic flow.
DATA Polling & Toggle Bit	Real-time write status via I/O7 complement or I/O6 toggling - eliminates fixed-delay polling loops and improves CPU efficiency.
64-byte page register	Reduces write overhead by 64× vs. byte-write mode; enables fast reprogramming of calibration tables or lookup data.

Applications

Avionics Flight Data Recorder	Military Radio Firmware Storage
Use Scenario: Nonvolatile storage of flight parameter logs and fault history in certified aircraft black boxes operating across −55°C to +125°C. IC Role / Device Role / Timing Role: Primary configuration and event log memory interfaced to 80C188EB microcontroller via parallel bus. Use Value: 10-year data retention and 10,000-cycle endurance ensure integrity of critical maintenance records without periodic refresh.	Use Scenario: Secure storage of encrypted radio boot code and cryptographic keys in handheld tactical radios exposed to vibration and thermal cycling. IC Role / Device Role / Timing Role: Firmware image repository with software write protection enabled to prevent unauthorized firmware modification. Use Value: Hardware VCC-sense and SDP prevent corruption during battery switchover or EMI-induced power glitches.
Secure Industrial PLC Configuration	Tactical Vehicle Control Module
Use Scenario: Storing calibrated sensor offsets and safety-critical control parameters in SIL-2-rated programmable logic controllers deployed in oilfield equipment. IC Role / Device Role / Timing Role: Parameter EEPROM accessed during cold start to initialize analog front-end and watchdog timers. Use Value: 200 ns read access enables full configuration load within first 50 µs of processor reset assertion.	Use Scenario: Mission-specific vehicle configuration (e.g., weapon interface mapping, comms channel presets) stored in armored ground vehicle ECUs. IC Role / Device Role / Timing Role: Field-updatable memory mapped into Z80 CPU address space for rapid reconfiguration between combat roles. Use Value: Page write capability reduces reprogramming time from >2 seconds (byte mode) to <150 ms for full 32K update.

Avionics Flight Data Recorder

Military Radio Firmware Storage

Use Scenario: Nonvolatile storage of flight parameter logs and fault history in certified aircraft black boxes operating across −55°C to +125°C.

IC Role / Device Role / Timing Role: Primary configuration and event log memory interfaced to 80C188EB microcontroller via parallel bus.

Use Value: 10-year data retention and 10,000-cycle endurance ensure integrity of critical maintenance records without periodic refresh.

Use Scenario: Secure storage of encrypted radio boot code and cryptographic keys in handheld tactical radios exposed to vibration and thermal cycling.

IC Role / Device Role / Timing Role: Firmware image repository with software write protection enabled to prevent unauthorized firmware modification.

Use Value: Hardware VCC-sense and SDP prevent corruption during battery switchover or EMI-induced power glitches.

Secure Industrial PLC Configuration

Tactical Vehicle Control Module

Use Scenario: Storing calibrated sensor offsets and safety-critical control parameters in SIL-2-rated programmable logic controllers deployed in oilfield equipment.

IC Role / Device Role / Timing Role: Parameter EEPROM accessed during cold start to initialize analog front-end and watchdog timers.

Use Value: 200 ns read access enables full configuration load within first 50 µs of processor reset assertion.

Use Scenario: Mission-specific vehicle configuration (e.g., weapon interface mapping, comms channel presets) stored in armored ground vehicle ECUs.

IC Role / Device Role / Timing Role: Field-updatable memory mapped into Z80 CPU address space for rapid reconfiguration between combat roles.

Use Value: Page write capability reduces reprogramming time from >2 seconds (byte mode) to <150 ms for full 32K update.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
AT28C256-20JM/883	Same die, 32-lead CERDIP package instead of CLCC; higher thermal resistance (θJA = 110°C/W vs. 75°C/W).	Suitable for through-hole assembly or legacy CERDIP socketed designs; less suitable for high-density surface-mount boards.	Select when board-level repairability or socket compatibility is prioritized over thermal performance or footprint density.
DS2502-E48+T&R	1-Wire serial interface (not parallel); 1024-bit EEPROM; no page write or hardware write protection.	Used in asset tagging and simple parameter storage where bus count reduction outweighs speed and security needs.	Choose only for ultra-low-pin-count systems where parallel bus resources are unavailable; not a functional substitute.

Compared with AT28C256-20JM/883, the AT28C256-20LM/883-815 offers superior thermal dissipation and smaller footprint in CLCC; compared with DS2502-E48+T&R, it delivers 256× more capacity, parallel-speed access, and military-grade write security - making it irreplaceable in deterministic real-time control.

Availability

AT28C256-20LM/883-815 is available at Aetrix Electronics and suitable for avionics data logging, military radio firmware storage, secure industrial PLC configuration, and tactical vehicle control modules requiring stable component supply under extended temperature and long-lifecycle conditions.

Supply support for AT28C256-20LM/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 company specializing in microcontrollers, analog devices, and nonvolatile memory solutions, with ISO 9001-certified manufacturing and MIL-PRF-38535-qualified product lines.

The AT28C256 product line was designed for high-reliability, radiation-tolerant, and extended-temperature embedded systems - specifically targeting defense, aerospace, and industrial control applications where data integrity and long-term availability are mandatory.

FAQ

What is the guaranteed read access time for AT28C256-20LM/883-815?

The AT28C256-20LM/883-815 guarantees a maximum read access time of 200 ns under military temperature range (−55°C to +125°C) and 5 V ±10% supply, as specified in Table 6-2 of Microchip DS20006344A. This value is tested and screened per MIL-PRF-38535 Class B requirements, ensuring deterministic timing in real-time avionics and control systems where AT28C256-20LM/883-815 is deployed.

Does AT28C256-20LM/883-815 support page write operations, and what is the maximum page size?

Yes, AT28C256-20LM/883-815 supports page write operations with a maximum page size of 64 bytes, as confirmed in Section 1 ("Features") and Table 6-4 of DS20006344A. The device internally latches address and data for up to 64 bytes, allowing sequential writes within 150 µs intervals before initiating automatic programming - a key capability leveraged in AT28C256-20LM/883-815-based firmware update routines.

How is write protection implemented on AT28C256-20LM/883-815?

AT28C256-20LM/883-815 implements dual-layer write protection: hardware-based (VCC sense below 3.8 V, 5 ms power-on delay, and <15 ns noise filtering on WE/CE) and software-based (3-byte unlock sequence AAh/55h/A0h to enable/disable SDP). Both mechanisms are fully operational across the −55°C to +125°C range and are integral to AT28C256-20LM/883-815's qualification for mission-critical military use.

What package type is used for AT28C256-20LM/883-815, and are pins 1 and 17 connected?

AT28C256-20LM/883-815 uses a 32-pad Ceramic Leadless Chip Carrier (CLCC) package per MIL-STD-1835 C-12. As documented in DS20006344A-page 4, pins 1 and 17 are explicitly designated "Don't Connect" - they have no internal connection and must remain unconnected in the PCB layout to maintain AT28C256-20LM/883-815 reliability and ESD immunity.

What is the endurance and data retention specification for AT28C256-20LM/883-815?

AT28C256-20LM/883-815 is rated for 10,000 write/erase cycles and 10 years of data retention at +125°C, per Section 1 ("Features") and Section 4.3 ("DC Characteristics") of DS20006344A. These values are production-tested and guaranteed for the full military temperature range, forming the basis for AT28C256-20LM/883-815's deployment in long-life, unattended systems such as satellite telemetry recorders and battlefield radios.

AT28C256-20LM/883-815 Specifications

Product attributes: Attribute value

Manufacturer:: Microchip Technology

Series:: -

Package/Case:: 32-CLCC

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:: 200 ns

Voltage - Supply:: 4.5V ~ 5.5V

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 32-LCC (11.43x13.97)

AT28C256-20LM/883-815 FAQ

1.How can I place an order for AT28C256-20LM/883-815 through Aetrix?

Please submit a Request for Quotation (RFQ) for AT28C256-20LM/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 AT28C256-20LM/883-815 reliable?

The price and inventory of AT28C256-20LM/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 AT28C256-20LM/883-815 is usually 5 days.

3.What payment methods are accepted for AT28C256-20LM/883-815?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28C256-20LM/883-815 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for AT28C256-20LM/883-815?

AT28C256-20LM/883-815 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your AT28C256-20LM/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 AT28C256-20LM/883-815?

For technical support, including AT28C256-20LM/883-815 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28C256-20LM/883-815 requirements.

6.How does Aetrix verify that AT28C256-20LM/883-815 is sourced from the original manufacturer or authorized distributors?

All AT28C256-20LM/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 AT28C256-20LM/883-815 meets industry standards.

7.What is the process for return or replacement of AT28C256-20LM/883-815?

All AT28C256-20LM/883-815 units undergo pre-shipment inspection (PSI). If there is an issue with AT28C256-20LM/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 AT28C256-20LM/883-815 part is unused and in its original packaging.

Return procedure for AT28C256-20LM/883-815:

1.Submit a request within 90 days.

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

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