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Microchip Technology AT28C256-25LM/883-829
- Part No.:
- AT28C256-25LM/883-829
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-CLCC
- Datasheet:
-
AT28C256-25LM/883-829.pdf
- Description:
- IC EEPROM 256KBIT PARALLEL 32LCC
- Quantity:
- Payment:
- Shipping:
Inventory:2,636
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Product details
Overview
AT28C256-25LM/883-829 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 AT28C256-25LM/883-829 datasheet, AT28C256-25LM/883-829 pinout, AT28C256-25LM/883-829 application, or AT28C256-25LM/883-829 equivalent, this page delivers verified military-spec timing, endurance (10,000 cycles), CMOS/TTL compatibility, and MIL-STD-883 Class B qualification details required for high-reliability system integration.
Technical Context
The AT28C256-25LM/883-829 implements a paged architecture with an internal 64-byte latch and autonomous control timer, enabling simultaneous multi-byte writes without external address/data bus hold. Its dual-line chip enable (CE) and output enable (OE) logic prevents bus contention in shared-memory systems.
It features VCC sense (write inhibit below 3.8 V), 5 ms power-on delay, noise filtering (<15 ns pulses rejected), and optional software data protection via three-byte unlock sequences. Device identification space (64 bytes at 7FC0H–7FFFH) is accessible using 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 - meets MIL-STD-883 Class B timing for real-time deterministic read response |
| Page Write Cycle | 10 ms max - enables burst programming of up to 64 bytes per internal cycle without host intervention |
| Endurance | 10,000 write/erase cycles - validated under military temperature range (−55°C to +125°C) |
| Data Retention | 10 years minimum - guaranteed at max operating temperature per MIL-STD-883 test conditions |
| Supply Voltage | 5 V ±10% - single-rail operation eliminates need for auxiliary voltage regulators |
| Operating Temp | −55°C to +125°C - qualified per MIL-STD-883 Method 1010.8 for extended environmental resilience |
Pinout & Package
AT28C256-25LM/883-829 is supplied in a 32-pad Ceramic Leadless Chip Carrier (CLCC) package compliant with MIL-STD-1835 C-12, with pins 1 and 17 designated "Don't Connect" per datasheet DS20006344A-page 4.
| 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 page 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 detection |
| CE | Chip Enable | Active-low device selection; must be low with OE low and WE high for read access |
| OE | Output Enable | Active-low output gating; controls tri-state behavior independently of CE to prevent bus contention |
| WE | Write Enable | Active-low write strobe; falling edge latches address/data; initiates byte or page programming sequence |
| VCC | Power Supply | +5 V ±10% input; includes internal VCC sense circuitry that inhibits writes below 3.8 V |
| GND | Ground Reference | Signal and power return path; decoupling required per MIL-STD-883 layout guidelines |
| DC (pins 1, 17) | No Connect | Unbonded terminals - must remain unconnected per CLCC mechanical specification |
Key Features
| Feature | Design Value |
|---|---|
| Page Write Architecture | 64-byte internal latch allows burst programming without host bus hold - reduces system latency by >90% vs. byte-by-byte writes |
| DATA Polling & Toggle Bit | Real-time end-of-write detection via I/O7 complement or I/O6 toggling - eliminates need for fixed delays or external timers |
| Hardware Write Protection | VCC sense, 5 ms power-on delay, and noise filtering ensure immunity to brownouts, glitches, and EMI-induced spurious writes |
| Software Data Protection | Three-byte unlock sequence (AAh/55h/A0h) enables selective write-enable - preserves firmware integrity during power transitions |
| MIL-STD-883 Qualification | Class B screening including temperature cycling, hermeticity, and radiation hardness assurance - certified for flight-critical subsystems |
Applications
| Avionics Flight Control Memory | Tactical Radio Configuration Storage |
|---|---|
Use Scenario: Storing real-time trim calibration tables and fail-safe control parameters in fly-by-wire ECUs requiring nonvolatile retention across thermal extremes. IC Role / Device Role / Timing Role: Parallel EEPROM providing deterministic 250 ns read access and 10 ms page writes for configuration bootstrapping and runtime parameter updates. Use Value: Eliminates external wait-state logic; 10,000-cycle endurance ensures 15+ year service life in mission-critical platforms. | Use Scenario: Holding encrypted channel maps, encryption keys, and RF profile settings in manpack radios deployed in desert and arctic environments. IC Role / Device Role / Timing Role: Secure, radiation-tolerant nonvolatile storage with software data protection preventing unauthorized reprogramming during field maintenance. Use Value: Hardware VCC-sense and 12 V device ID access enable tamper-evident provisioning and secure key management. |
| Missile Guidance System Boot ROM | Ruggedized Industrial PLC Firmware |
Use Scenario: Hosting immutable boot code and sensor initialization routines in inertial measurement units subjected to shock, vibration, and wide thermal swings. IC Role / Device Role / Timing Role: MIL-qualified EEPROM acting as primary boot memory with guaranteed 10-year data retention at +125°C junction temperature. Use Value: CLCC package provides hermetic sealing and thermal stability unmatched by plastic SOIC alternatives. | Use Scenario: Storing ladder logic configurations and I/O mapping tables in programmable logic controllers operating continuously in oil refinery control rooms. IC Role / Device Role / Timing Role: High-reliability parallel EEPROM interfacing directly with 8051/8086-style microcontrollers via standard address/data bus. Use Value: JEDEC byte-wide pinout ensures drop-in compatibility with legacy industrial designs; 300 µA standby current minimizes thermal load. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar paged parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28C256-25JU/883 | Same die, 32-lead CERDIP package instead of 32-pad CLCC; higher thermal resistance and lower vibration tolerance | Suitable for board-level applications where hermeticity is less critical than cost; not qualified for missile guidance use | Select only when CLCC assembly infrastructure is unavailable and MIL-STD-883 Class B screening suffices |
| DS2502-E48+T&R | 1-Wire serial EEPROM (48-bit ID + 1024-bit memory); no parallel bus interface; 5 V tolerant but no VCC sense or page write | Used for simple device identification or small-parameter storage where bus pin count is constrained | Not interchangeable - requires protocol stack changes and eliminates deterministic timing guarantees |
Compared with AT28C256-25JU/883, the AT28C256-25LM/883-829 offers superior thermal cycling performance and hermetic reliability in CLCC form, while DS2502-E48+T&R trades parallel speed and military qualification for ultra-low pin count and simplified wiring - making it unsuitable as a functional replacement.
Availability
AT28C256-25LM/883-829 is available at Aetrix Electronics and suitable for avionics flight control, tactical radio configuration, missile guidance system boot ROM, and ruggedized industrial PLC firmware requiring stable component supply across extended product lifecycles.
Supply support for AT28C256-25LM/883-829 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 Inc. is a global semiconductor company specializing in microcontrollers, analog devices, and nonvolatile memory solutions for industrial, automotive, and aerospace markets.
The AT28C256 product line was designed for high-reliability embedded systems requiring radiation-tolerant, temperature-stable, and long-retention nonvolatile storage - specifically targeting defense electronics and space-qualified subsystems.
FAQ
What is the maximum operating temperature range for the AT28C256-25LM/883-829?
The AT28C256-25LM/883-829 is qualified for operation from −55°C to +125°C per MIL-STD-883 Method 1010.8. This full military temperature range is validated through temperature cycling, steady-state burn-in, and parametric testing at both extremes - ensuring reliable functionality in jet engine bays, missile canisters, and desert-deployed radios. The AT28C256-25LM/883-829 maintains 250 ns read timing and 10 ms page write performance across this entire range.
Does the AT28C256-25LM/883-829 support hardware write protection independent of software commands?
Yes, the AT28C256-25LM/883-829 includes four independent hardware write protection mechanisms: VCC sense (inhibits writes below 3.8 V), 5 ms power-on delay timer, noise filtering rejecting <15 ns pulses on CE/WE, and active-high write inhibit via OE low, CE high, or WE high. These operate regardless of software data protection (SDP) state and are fully functional during power-up, brownout, and EMI events - ensuring robustness where SDP alone would fail. The AT28C256-25LM/883-829 relies on these circuits for its MIL-STD-883 Class B qualification.
How does DATA polling work on the AT28C256-25LM/883-829 during a page write operation?
During any write cycle (byte or page), reading the last written address returns the complement of the data on I/O7 until completion. Once the internal 10 ms timer finishes, true data appears on all I/O lines including I/O7. This allows the host processor to poll I/O7 without halting other operations - for example, a flight controller can verify write completion while simultaneously sampling IMU data. The AT28C256-25LM/883-829 guarantees this behavior across −55°C to +125°C and requires no additional hardware or timing margins.
Is the AT28C256-25LM/883-829 pin-compatible with commercial-grade AT28C256 variants?
Yes, the AT28C256-25LM/883-829 uses the JEDEC-approved byte-wide pinout identical to all AT28C256 family members, including commercial (e.g., AT28C256-25PI) and industrial variants. Pin functions (A0–A14, I/O0–I/O7, CE, OE, WE, VCC, GND) and electrical tolerances (CMOS/TTL compatibility, 5 V ±10%) are preserved. However, the AT28C256-25LM/883-829's CLCC package and MIL-STD-883 screening require updated reflow profiles and hermeticity validation - PCB layout is identical, but assembly process must comply with Class H requirements.
What package type is used for the AT28C256-25LM/883-829 and why is it suited for military applications?
The AT28C256-25LM/883-829 uses a 32-pad Ceramic Leadless Chip Carrier (CLCC) package per MIL-STD-1835 C-12. Its hermetically sealed ceramic body, gold-plated leads, and absence of organic materials provide immunity to moisture ingress, thermal shock, and outgassing in vacuum environments - critical for satellite payloads and high-altitude avionics. Unlike plastic or CERDIP packages, CLCC withstands 1,000+ thermal cycles between −55°C and +125°C without solder joint fatigue. The AT28C256-25LM/883-829 leverages this to achieve its 10-year data retention guarantee under sustained military operating conditions.
AT28C256-25LM/883-829 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:
- 250 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)
AT28C256-25LM/883-829 FAQ
1.How can I place an order for AT28C256-25LM/883-829 through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28C256-25LM/883-829 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 AT28C256-25LM/883-829 reliable?
The price and inventory of AT28C256-25LM/883-829 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28C256-25LM/883-829 is usually 5 days.
3.What payment methods are accepted for AT28C256-25LM/883-829?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28C256-25LM/883-829 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28C256-25LM/883-829?
AT28C256-25LM/883-829 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28C256-25LM/883-829 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 AT28C256-25LM/883-829?
For technical support, including AT28C256-25LM/883-829 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28C256-25LM/883-829 requirements.
6.How does Aetrix verify that AT28C256-25LM/883-829 is sourced from the original manufacturer or authorized distributors?
All AT28C256-25LM/883-829 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 AT28C256-25LM/883-829 meets industry standards.
7.What is the process for return or replacement of AT28C256-25LM/883-829?
All AT28C256-25LM/883-829 units undergo pre-shipment inspection (PSI). If there is an issue with AT28C256-25LM/883-829, 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 AT28C256-25LM/883-829 part is unused and in its original packaging.
Return procedure for AT28C256-25LM/883-829:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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