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Microchip Technology AT28C256-25DM/883
- Part No.:
- AT28C256-25DM/883
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-CDIP (0.600", 15.24mm)
- Datasheet:
-
AT28C256-25DM/883.pdf
- Description:
- IC EEPROM 256KBIT PAR 28CERDIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,272
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Product details
Overview
AT28C256-25DM/883 from Microchip Technology is a military-grade 256-Kbit (32,768 × 8) paged parallel EEPROM with 250 ns read access time, JEDEC-standard byte-wide pinout, and single 5V ±10% supply operation. It supports 1–64-byte page writes with ≤10 ms write cycle time and delivers 300 µA CMOS standby current for low-power embedded systems requiring nonvolatile storage in harsh environments.
For engineers reviewing the AT28C256-25DM/883 datasheet, AT28C256-25DM/883 pinout, AT28C256-25DM/883 application, or AT28C256-25DM/883 equivalent, this device serves as a drop-in replacement for legacy parallel EEPROMs in avionics, defense computing, and space-qualified data logging where MIL-STD-883 compliance, 10-year data retention, and hardware/software write protection are mandatory.
Technical Context
The AT28C256-25DM/883 implements a paged architecture with an internal 64-byte latch enabling burst writes without external address/data bus hold. Its dual-line chip enable (CE) and output enable (OE) control allows precise bus contention management in multi-master systems, while DATA Polling on I/O7 and Toggle Bit on I/O6 provide deterministic end-of-write detection independent of timing margins.
Hardware write protection includes VCC sense (<3.8 V inhibit), 5 ms power-on delay, noise filtering (<15 ns pulse rejection), and CE/OE/WE logic gating. Software Data Protection (SDP) uses a 3-byte command sequence (AAh/55h/A0h) to lock writes globally-retained across power cycles-and requires reissuing the sequence before each protected write.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Density | 256 Kbit (32,768 × 8) - provides sufficient nonvolatile storage for firmware boot code or configuration tables in resource-constrained military controllers. |
| Read Access Time | 250 ns max - enables direct interface with 4 MHz Z80 or 80C88-based systems without wait-state insertion. |
| Page Write Cycle Time | ≤10 ms - reduces system-level write latency versus byte-by-byte programming; supports rapid field updates in telemetry recorders. |
| Endurance | 10,000 write/erase cycles - validated under MIL-STD-883 Method 1037 for mission-critical applications with infrequent but reliable reprogramming. |
| Data Retention | 10 years at +125°C - guaranteed operation in extended-temperature avionics bays without refresh circuitry. |
| Supply Voltage | 5V ±10% - compatible with legacy TTL/CMOS logic rails and eliminates need for dedicated voltage regulators. |
| Standby Current | 300 µA CMOS - enables battery-backed operation in dormant subsystems for >1 year on a CR2032 cell. |
Pinout & Package
AT28C256-25DM/883 is packaged in a 32-lead CERDIP (Dual Inline Package) with ceramic hermetic seal and MIL-STD-883 qualification. Pin 1 is index corner; pins 1 and 17 are "Don't Connect" (DC) per CLCC variant marking, but unused in CERDIP.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus (32K words); A6–A14 define 64-byte page boundaries for atomic writes. |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel interface; I/O7 used for DATA Polling, I/O6 for Toggle Bit status indication during writes. |
| CE | Chip Enable | Active-low global 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; controls bus drive; high during write cycles to prevent contention. |
| WE | Write Enable | Active-low write strobe; falling edge latches address/data; rising edge triggers internal timer for page programming. |
| VCC | Power Supply | +5V ±10% main supply; internal VCC sense disables writes below 3.8 V to prevent corruption during brownout. |
| GND | Ground Reference | Signal and power return; decoupling capacitor required within 10 mm of VCC pin per MIL-STD-883 layout rules. |
Key Features
| Feature | Design Value |
|---|---|
| Paged Write Architecture | 64-byte internal latch enables burst programming without external address sequencing logic or microcontroller overhead. |
| DATA Polling & Toggle Bit | Dual asynchronous write-complete signaling: I/O7 returns complemented data until write finishes; I/O6 toggles until completion-no timer polling required. |
| Hardware Write Protection | VCC monitoring, 5 ms power-up delay, and noise-filtered CE/WE inputs eliminate need for external reset supervisors in ruggedized designs. |
| Software Data Protection (SDP) | User-configurable global lock via 3-byte command sequence; remains active across power cycles and prevents accidental overwrites in deployed systems. |
| MIL-STD-883 Qualified | Tested per Method 1037 (endurance), 1015 (thermal shock), and 2017 (hermeticity); marked "/883" confirms full military screening. |
Applications
| Avionics Flight Control Memory | Tactical Radio Configuration Storage |
|---|---|
Use Scenario: Stores flight control law parameters and sensor calibration coefficients in F-16 digital flight control computers. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed during power-up initialization and runtime parameter updates. Use Value: 250 ns read speed ensures real-time loading into FPGA configuration registers; 10-year retention guarantees integrity between depot maintenance cycles. |
Use Scenario: Holds frequency hopping tables and encryption keys in AN/PRC-117G manpack radios operating in desert environments. IC Role / Device Role / Timing Role: Secure, tamper-resistant storage with SDP enabled to prevent unauthorized reprogramming during field deployment. Use Value: Hardware VCC-sense protection prevents key corruption during vehicle battery transients; -55°C to +125°C operation sustains functionality in unheated radio enclosures. |
| Satellite Telemetry Recorder | Missile Guidance System Boot ROM |
Use Scenario: Captures pre-launch diagnostics and in-orbit health metrics in CubeSat telemetry modules exposed to vacuum and radiation. IC Role / Device Role / Timing Role: Radiation-tolerant nonvolatile buffer for time-stamped sensor data prior to downlink transmission. Use Value: Hermetic CERDIP package resists outgassing in vacuum; 10,000-cycle endurance supports repeated mission reconfiguration without replacement. |
Use Scenario: Stores inertial navigation initialization vectors and guidance algorithm constants in JASSM-ER cruise missile guidance units. IC Role / Device Role / Timing Role: Boot-time firmware repository accessed by radiation-hardened microcontroller during cold-start sequence. Use Value: JEDEC-standard pinout ensures compatibility with legacy MIL-STD-1553 bus controllers; 300 µA standby current extends battery life during long-term storage. |
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 instead of CERDIP; identical electrical specs and MIL-STD-883 screening. | Preferred for surface-mount PCBs with space constraints; requires different reflow profile due to ceramic lid construction. | Select when board assembly uses SMT processes and thermal cycling exceeds 1000 cycles-CLCC offers superior mechanical stability. |
| DS26528-25+T | Maxim Integrated 256-Kbit parallel EEPROM; 250 ns access, but only 5,000-cycle endurance and no SDP feature. | Suitable for commercial aerospace where cost sensitivity outweighs reprogrammability requirements. | Choose only if MIL-STD-883 qualification is not mandated and software write protection is unnecessary for the use case. |
Compared with AT28C256-25LM/883, the AT28C256-25DM/883 offers identical functionality in through-hole CERDIP for legacy repair or high-vibration mounting; versus DS26528-25+T, it delivers double endurance, full SDP, and verified military screening-critical for systems requiring guaranteed field reprogramming over 15+ years.
Availability
AT28C256-25DM/883 is available at Aetrix Electronics and suitable for avionics, tactical communications, and satellite subsystems requiring stable component supply across extended product lifecycles and rigorous environmental certification.
Supply support for AT28C256-25DM/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 company specializing in microcontrollers, analog devices, and nonvolatile memory solutions for industrial, automotive, and defense markets.
The AT28C256 product line was developed to replace obsolete EPROMs and early EEPROMs in military systems requiring radiation-tolerant, long-life, and field-programmable nonvolatile storage with deterministic timing behavior.
FAQ
What does the "/883" suffix indicate on AT28C256-25DM/883?
The "/883" suffix certifies that the AT28C256-25DM/883 has undergone full MIL-STD-883 testing-including Method 1037 (endurance), 1015 (thermal shock), and 2017 (hermeticity)-and meets military screening requirements for temperature range (-55°C to +125°C), reliability, and packaging integrity. This designation is mandatory for inclusion in DoD-accredited systems.
Can AT28C256-25DM/883 be used as a direct replacement for AT28C256-25DM without /883 screening?
No-AT28C256-25DM/883 is not a direct replacement for the commercial AT28C256-25DM. The /883 version undergoes additional burn-in, environmental stress, and parametric testing per MIL-STD-883, resulting in tighter parameter distributions and guaranteed operation across the full military temperature range. Substituting without requalification risks failure in vibration or thermal cycling tests.
How does the Software Data Protection (SDP) feature work on AT28C256-25DM/883?
SDP on AT28C256-25DM/883 is enabled by writing three specific bytes (AAh to 5555h, 55h to 2AAAh, A0h to 5555h) in sequence. Once activated, all subsequent writes require repeating this sequence before data. The AT28C256-25DM/883 retains SDP state across power cycles, preventing accidental overwrites during system resets or brownouts.
What is the maximum number of bytes that can be written in a single page operation on AT28C256-25DM/883?
The AT28C256-25DM/883 supports up to 64 bytes per page write operation. All bytes must reside within the same 64-byte page boundary defined by address bits A6–A14, and successive bytes must be loaded within 150 µs (tBLC) of each other. Exceeding this interval terminates the page load and initiates internal programming.
Does AT28C256-25DM/883 support chip erase functionality?
Yes-the AT28C256-25DM/883 supports optional software chip erase using a 6-byte command sequence applied with A9 = 12.0 V ± 0.5 V. This erases the entire 32,768-word array to FFh and is distinct from page or byte programming. The erase function is documented in Section 6.10 of the official Microchip datasheet DS20006344A.
AT28C256-25DM/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
AT28C256-25DM/883 FAQ
1.How can I place an order for AT28C256-25DM/883 through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28C256-25DM/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 AT28C256-25DM/883 reliable?
The price and inventory of AT28C256-25DM/883 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28C256-25DM/883 is usually 5 days.
3.What payment methods are accepted for AT28C256-25DM/883?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28C256-25DM/883 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28C256-25DM/883?
AT28C256-25DM/883 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28C256-25DM/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 AT28C256-25DM/883?
For technical support, including AT28C256-25DM/883 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28C256-25DM/883 requirements.
6.How does Aetrix verify that AT28C256-25DM/883 is sourced from the original manufacturer or authorized distributors?
All AT28C256-25DM/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 AT28C256-25DM/883 meets industry standards.
7.What is the process for return or replacement of AT28C256-25DM/883?
All AT28C256-25DM/883 units undergo pre-shipment inspection (PSI). If there is an issue with AT28C256-25DM/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 AT28C256-25DM/883 part is unused and in its original packaging.
Return procedure for AT28C256-25DM/883:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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