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Microchip Technology AT28C256-20DM/883-815
- Part No.:
- AT28C256-20DM/883-815
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-CDIP (0.600", 15.24mm)
- Datasheet:
-
AT28C256-20DM/883-815.pdf
- Description:
- IC EEPROM 256KBIT PAR 28CERDIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,648
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Product details
Overview
AT28C256-20DM/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 automatic 1–64-byte page writes with internal latching and data polling for write completion detection, deployed in avionics control modules requiring nonvolatile configuration storage under extended temperature cycling.
For engineers reviewing the AT28C256-20DM/883-815 datasheet, AT28C256-20DM/883-815 pinout, AT28C256-20DM/883-815 application, or AT28C256-20DM/883-815 equivalent, key selection criteria include its MIL-STD-883 Class B qualification, 10,000/100,000 write endurance rating, -55°C to +125°C operating range, hardware/software data protection, and compatibility with legacy 8-bit parallel bus architectures in defense electronics.
Technical Context
The AT28C256-20DM/883-815 implements a CMOS-based paged EEPROM architecture with a 64-byte internal page register, 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 during read cycles.
Write operations are governed by an internal control timer supporting both byte and page modes, with DATA Polling on I/O7 and Toggle Bit on I/O6 providing asynchronous write completion signaling. Hardware protection includes VCC sense (<3.8V inhibit), 5 ms power-on delay, and noise filtering on WE/CE inputs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Density | 256 Kbit (32,768 × 8) - fixed byte-wide organization compatible with 8-bit microprocessor data buses |
| Read Access Time | 200 ns max - meets timing requirements for 5 MHz bus operation with margin |
| Page Write Cycle Time | 10 ms max (standard) or 3 ms max (F variant) - determines minimum interval between successive page writes |
| Operating Temperature | -55°C to +125°C - qualified per MIL-STD-883 for sustained operation in harsh environmental enclosures |
| Endurance | 10,000 or 100,000 write/erase cycles - selectable via part marking; defines field-replaceable lifetime in reprogrammable systems |
| Data Retention | 10 years at +125°C - ensures firmware/config integrity over full military lifecycle without refresh |
| Supply Voltage | 5V ±10% - eliminates need for dedicated voltage regulation in legacy 5V system designs |
| Standby Current | 300 µA CMOS - enables low-power sleep modes in battery-backed subsystems |
Pinout & Package
AT28C256-20DM/883-815 is packaged in a 32-lead CERDIP (Dual Inline Package) with ceramic hermetic seal and military-grade glass frit sealing per MIL-STD-1835 D-10 Config A. Pin 1 is marked with notch or dot; pins 1 and 17 are "Don't Connect" (DC) per CLCC variant but not present in CERDIP layout.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus selecting one of 32,768 bytes; A6–A14 define page boundary for 64-byte page writes |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel interface; I/O7 provides DATA Polling feedback, I/O6 provides Toggle Bit status |
| CE | Chip Enable | Active-low device select; must be low for read/write; high-Z output when asserted high |
| OE | Output Enable | Active-low output gate; controls data bus drive during reads; must be high during writes |
| WE | Write Enable | Active-low write strobe; falling edge latches address/data; initiates internal programming timer |
| VCC | Power Supply | +5V ±10% main supply; powers all logic and memory cells; VCC sense disables writes below 3.8V |
| GND | Ground Reference | Signal and power return; decoupling capacitor required within 10 mm of VCC/GND pins |
Key Features
| Feature | Design Value |
|---|---|
| JEDEC Byte-Wide Pinout | Direct drop-in replacement for industry-standard 27C256 EPROMs and earlier EEPROMs in existing PCB layouts |
| Automatic Page Write | Reduces host CPU overhead by allowing up to 64 bytes to be loaded before internal write begins - no external timing control needed |
| Hardware + Software Data Protection | VCC sensing, 5 ms power-on delay, and 3-byte SDP command sequence prevent accidental writes during brown-out or reset conditions |
| DATA Polling & Toggle Bit | Two independent, asynchronous methods (I/O7 complement, I/O6 toggle) for detecting write completion without busy-wait loops |
| Extended Identification Area | 64-byte reserved sector (7FC0H–7FFFH) accessible at 12V on A9 for unique device serialization or calibration data storage |
| MIL-STD-883 Qualification | Class B screening including temperature cycling, mechanical shock, and hermeticity testing - certified for flight-critical avionics use |
Applications
| Avionics Configuration Storage | Secure Bootloader Parameter Retention |
|---|---|
Use Scenario: Storing aircraft-specific navigation parameters, sensor calibration coefficients, and flight control trim settings in airborne mission computers. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed during power-up initialization and runtime parameter updates via parallel bus. Use Value: 10-year data retention at +125°C ensures integrity across multi-year deployment without maintenance; MIL-STD-883 qualification guarantees reliability under vibration and thermal stress. |
Use Scenario: Holding cryptographic keys, secure boot flags, and firmware version metadata in encrypted bootloader environments. IC Role / Device Role / Timing Role: Trusted persistent storage for security-critical values, protected by hardware VCC sense and software data protection (SDP). Use Value: Dual-layer protection prevents unauthorized or glitch-induced writes; 100,000-cycle endurance supports frequent key rotation in field-upgradable systems. |
| Tactical Radio Firmware Patch Storage | Weapon System Safety Interlock Tables |
Use Scenario: Storing field-loadable firmware patches and protocol stack updates in man-portable HF/VHF radios operating in extreme desert or arctic conditions. IC Role / Device Role / Timing Role: Field-programmable code repository accessed via microcontroller's external memory interface during OTA update sequences. Use Value: 200 ns read access enables real-time patch execution; page write capability reduces update time versus byte-by-byte programming. |
Use Scenario: Maintaining safety-critical interlock state tables and arming/disarming logic maps in guided munition guidance sections. IC Role / Device Role / Timing Role: Fail-safe nonvolatile lookup table referenced by FPGA or ASIC safety monitor during pre-launch self-test and launch sequence. Use Value: Hermetic CERDIP package prevents moisture ingress in sealed ordnance housings; -55°C to +125°C range covers full operational envelope. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar paged parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28C256-25DM/883 | 250 ns read access time; otherwise identical electrical and functional specification | Suitable where 5 MHz bus timing margin is relaxed or system clock rate is lower | Select when cost sensitivity outweighs speed requirement and 250 ns timing satisfies design margins |
| AT28C256-15DM/883 | 150 ns read access time; same endurance, temperature, and protection features | Required for tighter-timing 8-MHz bus interfaces or high-speed microcontroller co-processor links | Choose when system-level timing analysis confirms need for sub-200 ns access; verify VCC stability under fast switching |
Compared with AT28C256-20DM/883-815, the -15 variant offers faster read response for high-throughput data logging, while the -25 variant trades speed for broader timing margin in thermally constrained deployments - all share identical pinout, software protection, and MIL-STD-883 qualification.
Availability
AT28C256-20DM/883-815 is available at Aetrix Electronics and suitable for avionics control modules, secure bootloader implementations, tactical radio firmware storage, and weapon system safety interlock applications requiring stable component supply across extended product lifecycles.
Supply support for AT28C256-20DM/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 a focus on industrial, automotive, and aerospace markets.
The AT28C256 product line delivers radiation-tolerant, high-reliability parallel EEPROMs designed specifically for military and space-grade applications demanding long-term data integrity and guaranteed manufacturability under MIL-STD-883 screening.
FAQ
What is the maximum operating temperature range for the AT28C256-20DM/883-815?
The AT28C256-20DM/883-815 is qualified for continuous operation from -55°C to +125°C per MIL-STD-883 Class B requirements. This range is validated through temperature cycling, steady-state burn-in, and parametric testing at extremes - critical for deployment in engine-mounted avionics or desert-deployed radios where ambient heat exceeds commercial limits. The AT28C256-20DM/883-815 maintains full read/write functionality and data retention specifications across this full span.
Does the AT28C256-20DM/883-815 support both hardware and software write protection?
Yes, the AT28C256-20DM/883-815 implements dual-layer protection: hardware features include VCC sense (inhibits writes below ~3.8V), 5 ms power-on delay, and noise filtering on WE/CE inputs; software protection uses a 3-byte command sequence (AAh→55h→A0h) to enable/disable write lock. Once enabled, the AT28C256-20DM/883-815 requires the same sequence before any write - preventing corruption during power transitions or EMI events.
How does DATA Polling work on the AT28C256-20DM/883-815 during a write cycle?
During a write cycle, reading the last written byte from the AT28C256-20DM/883-815 returns the bitwise complement on I/O7 until completion. When true data appears on I/O7, the write has finished. This allows the host processor to poll asynchronously without fixed delays - essential for deterministic real-time systems. The AT28C256-20DM/883-815 supports polling at any time during tWC (max 10 ms), and I/O7 remains stable post-completion.
What package type is used for the AT28C256-20DM/883-815?
The AT28C256-20DM/883-815 uses a 32-lead CERDIP (Ceramic Dual Inline Package) with glass-sealed construction per MIL-STD-1835 D-10 Config A. It features a 0.600" wide body, 0.100" lead pitch, and hermetic cavity for moisture resistance - standard for military applications requiring long-term reliability in humid or corrosive environments. Pin 1 is identified by a notch or dot; no "Don't Connect" pins exist in this CERDIP variant.
Can the AT28C256-20DM/883-815 be used as a direct replacement for older 27C256 EPROMs?
Yes, the AT28C256-20DM/883-815 uses JEDEC-approved byte-wide pinout and operates on the same 5V supply as 27C256 EPROMs, enabling drop-in replacement in existing sockets. Key differences include built-in write capability (no UV eraser needed), automatic page write, and hardware/software protection - but read timing (200 ns) and address/data bus behavior match closely enough for seamless integration in legacy 8-bit systems without PCB modification.
AT28C256-20DM/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:
- 200 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
AT28C256-20DM/883-815 FAQ
1.How can I place an order for AT28C256-20DM/883-815 through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28C256-20DM/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 AT28C256-20DM/883-815 reliable?
The price and inventory of AT28C256-20DM/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 AT28C256-20DM/883-815 is usually 5 days.
3.What payment methods are accepted for AT28C256-20DM/883-815?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28C256-20DM/883-815 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28C256-20DM/883-815?
AT28C256-20DM/883-815 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28C256-20DM/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 AT28C256-20DM/883-815?
For technical support, including AT28C256-20DM/883-815 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28C256-20DM/883-815 requirements.
6.How does Aetrix verify that AT28C256-20DM/883-815 is sourced from the original manufacturer or authorized distributors?
All AT28C256-20DM/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 AT28C256-20DM/883-815 meets industry standards.
7.What is the process for return or replacement of AT28C256-20DM/883-815?
All AT28C256-20DM/883-815 units undergo pre-shipment inspection (PSI). If there is an issue with AT28C256-20DM/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 AT28C256-20DM/883-815 part is unused and in its original packaging.
Return procedure for AT28C256-20DM/883-815:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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