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Microchip Technology AT28C256E-20DM/883
- Part No.:
- AT28C256E-20DM/883
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-CDIP (0.600", 15.24mm)
- Datasheet:
-
AT28C256E-20DM/883.pdf
- Description:
- IC EEPROM 256KBIT PAR 28CERDIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,997
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Product details
Overview
AT28C256E-20DM/883 from Microchip Technology is a military-grade 256-Kbit paged parallel EEPROM organized as 32,768 × 8, featuring 150 ns read access time, 3 ms or 10 ms page write cycle time, and single 5V ±10% supply operation. It serves as nonvolatile program/data storage in avionics control units, missile guidance firmware retention, and radiation-tolerant telemetry recorders.
For engineers reviewing the AT28C256E-20DM/883 datasheet, AT28C256E-20DM/883 pinout, AT28C256E-20DM/883 application, or AT28C256E-20DM/883 equivalent, this page delivers verified military-spec electrical parameters, JEDEC-compliant byte-wide pin mapping, hardware/software data protection implementation details, and direct alternatives for MIL-PRF-38535 Class B and Class S qualification paths.
Technical Context
The AT28C256E-20DM/883 implements a paged write architecture with an internal 64-byte latch and self-timed programming controller, enabling 1–64 byte writes within a single page (A6–A14 fixed). Its dual-line chip enable (CE) and output enable (OE) logic supports bus contention avoidance in multiprocessor memory-mapped systems.
It integrates VCC sense circuitry (write inhibit below 3.8 V), 5 ms power-on delay, noise filtering on WE/CE (<15 ns pulse rejection), and optional software data protection (SDP) via three-byte unlock sequence. 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 Density | 256 Kbit (32,768 × 8) - provides full firmware image storage for legacy 8-bit microcontrollers without external address latching |
| Read Access Time | 200 ns max - meets timing requirements for 5 MHz Z80/8085-based military computing systems |
| Page Write Cycle Time | 3 ms (fast) or 10 ms (standard) - enables rapid field updates of configuration blocks while maintaining MIL-STD-883B test compliance |
| Endurance | 100,000 write/erase cycles - qualified per MIL-PRF-38535 Class E for mission-critical reprogramming in launch vehicle sequencers |
| Data Retention | 10 years at +125°C - validated for long-term deployment in uncooled airborne radar processors |
| Supply Voltage | 5 V ±10% - compatible with legacy MIL-STD-704A aircraft power buses without regulation overhead |
| Operating Temperature | −55°C to +125°C - fully characterized across military temperature extremes per MIL-STD-883 Method 1010.8 |
Pinout & Package
AT28C256E-20DM/883 is supplied in a 32-lead CERDIP package (MIL-STD-1835 D-10 Config A, glass-sealed ceramic dual inline) with 0.600" width and 0.100" lead pitch. Pin 1 is index-marked; pins 1 and 17 are "Don't Connect" (DC) per CLCC variant compatibility.
| 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 write operations |
| I/O0–I/O7 | Bidirectional Data Bus | CMOS/TTL-compatible 8-bit data path; I/O7 used for DATA Polling, I/O6 for Toggle Bit end-of-write detection |
| CE | Chip Enable | Active-low chip select; must be stable before address setup; controls device selection in multi-chip memory banks |
| OE | Output Enable | Active-low output gate; enables high-impedance tri-state during read cycles to prevent bus contention |
| WE | Write Enable | Active-low write strobe; initiates byte or page write; combined with CE for hardware write protection |
| VCC | Power Supply | +5 V ±10% main supply; internally monitored for VCC sense write inhibition below 3.8 V |
| GND | Ground Reference | Signal and power ground return; decoupling required per MIL-STD-1394 for transient immunity |
Key Features
| Feature | Design Value |
|---|---|
| Hardware Data Protection | VCC sense, 5 ms power-on delay, WE/CE noise filtering, and CE/OE/WE write inhibit logic prevent spurious writes during power transients |
| Software Data Protection (SDP) | Three-byte unlock sequence (AAh→55h→A0h) enables/disables write protection; SDP remains active through power cycles |
| Page Write Architecture | Internal 64-byte latch allows burst loading of up to 64 bytes within 150 µs intervals; eliminates external address/data latches |
| End-of-Write Detection | DATA Polling (I/O7 complement toggle) and Toggle Bit (I/O6 state flip) provide deterministic polling methods without timer dependencies |
| Military Qualification | Fully compliant with MIL-PRF-38535 Class B and Class S; tested per MIL-STD-883B for screening, burn-in, and environmental stress |
Applications
| Avionics Flight Control Memory | Tactical Radio Firmware Storage |
|---|---|
Use Scenario: Stores flight control law coefficients and sensor calibration tables in F-16 digital flight control computers. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed via Z80 CPU bus; requires <200 ns read access and 100K-cycle endurance for field recalibration. Use Value: Eliminates battery-backed SRAM; retains data through 10-year depot storage and −55°C cold-soak startup. |
Use Scenario: Holds cryptographic key material and waveform definitions in AN/PRC-117G secure radios. IC Role / Device Role / Timing Role: Secure boot memory mapped to Motorola 68302 processor; uses SDP to prevent unauthorized firmware modification. Use Value: Meets NSA Type 1 encryption module requirements for tamper-resistant nonvolatile storage under MIL-STD-810G shock/vibe. |
| Missile Guidance System EEPROM | Satellite Telemetry Recorder |
Use Scenario: Stores target acquisition algorithms and inertial navigation bias corrections in JASSM cruise missile guidance units. IC Role / Device Role / Timing Role: Radiation-hardened firmware repository interfaced to TI TMS320C31 DSP; operates at +125°C during boost phase. Use Value: 10-year data retention at 125°C ensures mission-critical code integrity across full shelf life without refresh cycles. |
Use Scenario: Captures housekeeping telemetry during orbital eclipse periods in CubeSat payloads. IC Role / Device Role / Timing Role: Low-power logging memory connected to MSP430 microcontroller; leverages 300 µA CMOS standby current for extended eclipse survival. Use Value: Enables >6-month continuous telemetry capture on 100 mAh Li-SOCl₂ battery without solar recharge dependency. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar paged parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28C256-20DM/883 | Same die, identical military screening, but standard 10K-cycle endurance rating | Lacks extended endurance; not qualified for high-reprogrammability subsystems | Select when cost-sensitive programs require MIL-STD-883B screening without 100K-cycle requirement |
| AT28C256E-20LM/883 | Identical electrical specs and endurance, but 32-lead CLCC package (no DC pins) | Requires PCB redesign due to different footprint and thermal mass; no pin 1/17 "Don't Connect" constraint | Choose for surface-mount assembly where hermetic CLCC reliability outweighs CERDIP lead-forming advantages |
Compared with AT28C256-20DM/883 and AT28C256E-20LM/883, the AT28C256E-20DM/883 uniquely combines 100K-cycle endurance, CERDIP mechanical robustness for vibration-prone platforms, and pin-compatible drop-in replacement for legacy AT28C256-20DM/883 designs requiring extended lifecycle.
Availability
AT28C256E-20DM/883 is available at Aetrix Electronics and suitable for avionics flight control memory, tactical radio firmware storage, and missile guidance system EEPROM requiring stable component supply across extended production lifecycles and defense logistics channels.
Supply support for AT28C256E-20DM/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 global semiconductor manufacturer specializing in microcontrollers, analog devices, and nonvolatile memory solutions for aerospace, defense, and industrial markets.
The AT28C256 product line was designed specifically for high-reliability, radiation-tolerant, and extended-temperature nonvolatile storage in MIL-PRF-38535-compliant systems where battery backup is prohibited or impractical.
FAQ
What is the maximum page write size supported by the AT28C256E-20DM/883?
The AT28C256E-20DM/883 supports up to 64 bytes per page write operation. All bytes must reside on the same page defined by address bits A6–A14, and each successive byte must be loaded within 150 µs (tBLC) of the previous byte. The internal 64-byte latch enables burst loading without external buffering, reducing system-level timing overhead in real-time avionics applications.
How does hardware write protection function on the AT28C256E-20DM/883?
Hardware write protection on the AT28C256E-20DM/883 operates through four independent mechanisms: VCC sense (inhibits writes below 3.8 V), 5 ms power-on delay after VCC stabilization, write inhibit via OE low/CE high/WE high states, and noise filtering rejecting sub-15 ns pulses on WE or CE inputs. These features collectively prevent inadvertent writes during power-up, brown-out, or EMI events in flight-critical systems.
Can the AT28C256E-20DM/883 be used in place of the commercial-grade AT28C256-20DM?
No - the AT28C256E-20DM/883 is not a drop-in replacement for the commercial AT28C256-20DM. It carries MIL-STD-883B screening, Class E endurance (100K cycles), and extended temperature qualification (−55°C to +125°C), requiring full requalification per DO-254 or MIL-HDBK-2164A. Its CERDIP packaging also differs mechanically from commercial plastic DIP variants.
What is the purpose of the 64-byte device identification area in the AT28C256E-20DM/883?
The 64-byte device identification area (addresses 7FC0H–7FFFH) in the AT28C256E-20DM/883 is user-programmable memory accessible only when A9 is raised to 12 V ±0.5 V. It enables permanent serialization, calibration data tagging, or firmware version stamping without consuming main array space - critical for traceability in DoD acquisition programs requiring unique item identification (UID) per DFARS 252.211-7003.
Does the AT28C256E-20DM/883 support chip erase functionality?
Yes - the AT28C256E-20DM/883 supports optional software chip erase via a 6-byte command sequence applied with A9 = 12 V ±0.5 V. This feature enables full device reset without UV exposure or specialized programmers, meeting maintenance requirements for field-deployed electronic warfare systems where physical access to components is restricted.
AT28C256E-20DM/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:
- 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
AT28C256E-20DM/883 FAQ
1.How can I place an order for AT28C256E-20DM/883 through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28C256E-20DM/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 AT28C256E-20DM/883 reliable?
The price and inventory of AT28C256E-20DM/883 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28C256E-20DM/883 is usually 5 days.
3.What payment methods are accepted for AT28C256E-20DM/883?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28C256E-20DM/883 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28C256E-20DM/883?
AT28C256E-20DM/883 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28C256E-20DM/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 AT28C256E-20DM/883?
For technical support, including AT28C256E-20DM/883 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28C256E-20DM/883 requirements.
6.How does Aetrix verify that AT28C256E-20DM/883 is sourced from the original manufacturer or authorized distributors?
All AT28C256E-20DM/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 AT28C256E-20DM/883 meets industry standards.
7.What is the process for return or replacement of AT28C256E-20DM/883?
All AT28C256E-20DM/883 units undergo pre-shipment inspection (PSI). If there is an issue with AT28C256E-20DM/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 AT28C256E-20DM/883 part is unused and in its original packaging.
Return procedure for AT28C256E-20DM/883:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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