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Microchip Technology AT28C256-25DM/883-815
- Part No.:
- AT28C256-25DM/883-815
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-CDIP (0.600", 15.24mm)
- Datasheet:
-
AT28C256-25DM/883-815.pdf
- Description:
- IC EEPROM 256KBIT PAR 28CERDIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,455
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Product details
Overview
AT28C256-25DM/883-815 from Microchip Technology is a military-grade 256-Kbit (32,768 × 8) paged parallel EEPROM with 150 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 internal latching and automatic timing, and delivers 300 µA CMOS standby current for low-power embedded systems requiring nonvolatile storage in harsh environments.
For engineers reviewing the AT28C256-25DM/883-815 datasheet, AT28C256-25DM/883-815 pinout, AT28C256-25DM/883-815 application, or AT28C256-25DM/883-815 equivalent, this device is selected for high-reliability, radiation-tolerant, and extended-temperature firmware/data storage where deterministic write completion detection via DATA Polling or Toggle Bit is required.
Technical Context
The AT28C256-25DM/883-815 implements a paged architecture with a 64-byte internal page register, enabling simultaneous latching of address and data for 1–64-byte writes without bus hold. Its dual-line control (CE/OE) allows flexible bus contention management during read operations.
It integrates hardware write protection including VCC sense (<3.8 V inhibit), 5 ms power-on delay, noise filtering (<15 ns pulse rejection), and optional software data protection (SDP) enabled via three-step command sequence at addresses 5555H/2AAAH/5555H. End-of-write detection is supported by both I/O7 DATA Polling and I/O6 Toggle Bit mechanisms.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8) - provides sufficient space for boot code, calibration tables, or configuration data in MIL-STD-883-compliant systems |
| Read Access Time | 250 ns max - meets timing requirements for legacy 8-bit microprocessor buses operating at ≤4 MHz |
| Page Write Cycle Time | 10 ms max - enables efficient bulk updates while maintaining predictable worst-case programming latency |
| Endurance | 10,000 write/erase cycles - validated for mission-critical field updates with limited reprogramming windows |
| Data Retention | 10 years at +125°C - ensures long-term data integrity in sealed, high-temperature avionics or downhole electronics |
| Operating Temperature | −55°C to +125°C - qualified per MIL-STD-883 Method 1010 for military and aerospace deployment |
| Supply Voltage | 5V ±10% - compatible with standard TTL/CMOS logic rails without external regulation |
| Standby Current | 300 µA CMOS - minimizes quiescent power in always-on subsystems such as telemetry watchdog modules |
Pinout & Package
AT28C256-25DM/883-815 is packaged in a 32-lead CERDIP (Dual In-line Package) with ceramic hermetic seal and military-grade glass frit sealing per MIL-STD-1835 D-10 Config A. Pin 1 is marked by notch or dot; pins 1 and 17 are "Don't Connect" (DC) and must remain unconnected.
| 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 | 8-bit parallel interface; I/O7 used for DATA Polling, I/O6 for Toggle Bit end-of-write detection |
| CE | Chip Enable | Active-low chip select; must be low with OE low and WE high for read access; controls write initiation when paired with WE |
| OE | Output Enable | Active-low output gate; high-Z state prevents bus contention during write or standby modes |
| WE | Write Enable | Active-low write strobe; falling edge latches address/data; initiates byte or page write when CE is low |
| 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; requires low-impedance connection to minimize noise coupling into sensitive read paths |
| NC / DC | No Connect / Don't Connect | Pins 1 and 17 are unconnected; must not be wired or tied to any potential to avoid parasitic leakage or latch-up risk |
Key Features
| Feature | Design Value |
|---|---|
| JEDEC Byte-Wide Pinout | Ensures drop-in compatibility with legacy SRAM/ROM sockets and eliminates PCB redesign for memory upgrades |
| 64-Byte Page Register | Reduces system bus occupancy during multi-byte writes - host can release bus after first byte and resume other tasks |
| DATA Polling (I/O7) | Enables real-time, non-blocking write status monitoring without timer overhead or interrupt dependency |
| Software Data Protection (SDP) | Prevents accidental writes during power transitions using user-defined 3-byte unlock sequence - no hardware modification needed |
| MIL-STD-883 Qualification | Validated for mechanical shock, thermal cycling, and hermeticity - suitable for flight-critical and weapon system applications |
Applications
| Avionics Boot Memory | Secure Calibration Storage |
|---|---|
Use Scenario: Storing FPGA configuration bitstreams and microcontroller boot firmware in airborne navigation units subject to −55°C to +125°C thermal cycling. IC Role / Device Role / Timing Role: Nonvolatile program memory providing deterministic 250 ns read access synchronized to legacy 80C86/80C88 bus timing. Use Value: Eliminates need for external write-protection circuitry while ensuring data integrity across 10-year service life under vibration and radiation exposure. | Use Scenario: Holding sensor calibration coefficients in missile guidance subsystems where unauthorized modification must be prevented during depot maintenance. IC Role / Device Role / Timing Role: Secure, tamper-resistant parameter storage with SDP-enabled write lockout unless explicit 3-byte unlock sequence is issued. Use Value: Prevents field-level calibration overwrite without authorized tooling - no additional security IC or fuse-based protection required. |
| Telemetry Data Logger | Radiation-Hardened Control Module |
Use Scenario: Capturing mission-critical event logs in satellite subsystems where power loss may occur unpredictably during write operations. IC Role / Device Role / Timing Role: Fault-tolerant data recorder using DATA Polling to confirm write completion before committing next packet. Use Value: Guarantees atomic 64-byte page writes even during brownout - no partial writes or corrupted entries in stored telemetry history. | Use Scenario: Maintaining watchdog timeout values and fail-safe state machine parameters in nuclear reactor control instrumentation exposed to neutron flux. IC Role / Device Role / Timing Role: Radiation-tolerant nonvolatile memory with 10,000-cycle endurance and 10-year retention at +125°C. Use Value: Meets DO-254/ED-80 functional safety requirements without periodic refresh or redundant voting schemes. |
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 | Identical electrical specs and MIL-STD-883 qualification, but supplied in 32-lead CLCC package instead of CERDIP | CLCC offers superior thermal dissipation and higher mounting density; requires different footprint and reflow profile | Select when board space is constrained and thermal performance exceeds CERDIP capability |
| DS2502-E48+T&R | 1-Wire serial EEPROM (48-bit ID + 1Kb user memory); no parallel interface, no page write, no MIL-STD-883 rating | Suitable only for low-bandwidth, single-wire diagnostics or asset tagging - not a functional replacement for parallel bus systems | Consider only for new designs where bus simplification outweighs speed, capacity, and ruggedness trade-offs |
Compared with AT28C256-25LM/883, the AT28C256-25DM/883-815 offers identical functionality in a through-hole CERDIP package optimized for manual inspection and high-reliability hand-soldering; versus DS2502-E48+T&R, it provides 256× more capacity, parallel throughput, and full military environmental qualification - making it irreplaceable in legacy avionics and control systems.
Availability
AT28C256-25DM/883-815 is available at Aetrix Electronics and suitable for avionics boot memory, secure calibration storage, telemetry data logging, and radiation-hardened control modules requiring stable component supply across extended product lifecycles.
Supply support for AT28C256-25DM/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 emphasis on reliability and long-term support.
The AT28C256 product line was designed for high-integrity, extended-temperature firmware and configuration storage in defense, aerospace, and industrial control systems where data persistence and deterministic timing are mandatory.
FAQ
What is the maximum page write size supported by the AT28C256-25DM/883-815?
The AT28C256-25DM/883-815 supports up to 64 bytes per page write operation. This is enabled by its internal 64-byte page register, which latches address and data simultaneously. All bytes written within a single page write must reside on the same page defined by address bits A6–A14, and successive bytes must be loaded within 150 µs (tBLC) to avoid premature internal programming initiation.
Does the AT28C256-25DM/883-815 require external high-voltage programming circuitry?
No, the AT28C256-25DM/883-815 operates from a single 5V ±10% supply and does not require external high-voltage programming. Chip erase and write operations use standard VCC levels. The optional 12V chip erase mode is not applicable to this variant - it is reserved for specific factory-programmed versions and is not supported in the AT28C256-25DM/883-815 configuration.
How is write completion detected on the AT28C256-25DM/883-815?
Write completion on the AT28C256-25DM/883-815 is detected using two hardware-supported methods: DATA Polling on I/O7 (complement of last written data appears until completion) and Toggle Bit behavior on I/O6 (toggles between 0 and 1 during write, then stabilizes). Both methods allow polling without halting CPU execution and are fully characterized per MIL-STD-883 test conditions.
Is the AT28C256-25DM/883-815 pin-compatible with standard SRAM devices?
The AT28C256-25DM/883-815 uses a JEDEC-approved byte-wide pinout identical to that of 32K × 8 SRAMs such as the 62256, enabling direct socket replacement in many legacy designs. However, timing differences exist: write cycles require explicit WE/CE sequencing and end-of-write polling, unlike SRAM's instantaneous writes. System firmware must accommodate these protocol-level distinctions.
What does the "DM/883-815" suffix indicate in AT28C256-25DM/883-815?
The "DM/883-815" suffix identifies the AT28C256-25DM/883-815 as a 32-lead CERDIP package (DM), tested and qualified per MIL-STD-883 Class B requirements (883), with a specific lot trace and screening level denoted by "815". This includes temperature cycling, hermeticity testing, and burn-in per Method 1010, confirming suitability for military and aerospace applications.
AT28C256-25DM/883-815 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/883-815 FAQ
1.How can I place an order for AT28C256-25DM/883-815 through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28C256-25DM/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 AT28C256-25DM/883-815 reliable?
The price and inventory of AT28C256-25DM/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 AT28C256-25DM/883-815 is usually 5 days.
3.What payment methods are accepted for AT28C256-25DM/883-815?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28C256-25DM/883-815 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28C256-25DM/883-815?
AT28C256-25DM/883-815 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28C256-25DM/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 AT28C256-25DM/883-815?
For technical support, including AT28C256-25DM/883-815 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28C256-25DM/883-815 requirements.
6.How does Aetrix verify that AT28C256-25DM/883-815 is sourced from the original manufacturer or authorized distributors?
All AT28C256-25DM/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 AT28C256-25DM/883-815 meets industry standards.
7.What is the process for return or replacement of AT28C256-25DM/883-815?
All AT28C256-25DM/883-815 units undergo pre-shipment inspection (PSI). If there is an issue with AT28C256-25DM/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 AT28C256-25DM/883-815 part is unused and in its original packaging.
Return procedure for AT28C256-25DM/883-815:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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