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Microchip Technology AT28C256E-20UM/883
- Part No.:
- AT28C256E-20UM/883
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-BCPGA
- Datasheet:
-
AT28C256E-20UM/883.pdf
- Description:
- IC EEPROM 256KBIT PAR 28CPGA
- Quantity:
- Payment:
- Shipping:
Inventory:1,584
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Product details
Overview
AT28C256E-20UM/883 from Microchip Technology is a military-grade 256-Kbit (32,768 × 8) paged parallel EEPROM with 200 ns read access time, 10 ms maximum page write cycle, and single 5V ±10% supply operation. It features hardware/software data protection, DATA polling and toggle-bit write completion detection, and is used in avionics control modules requiring nonvolatile storage with radiation-tolerant packaging.
For engineers reviewing the AT28C256E-20UM/883 datasheet, AT28C256E-20UM/883 pinout, AT28C256E-20UM/883 application, or AT28C256E-20UM/883 equivalent, this page delivers verified military-spec electrical parameters, JEDEC-compliant byte-wide pin mapping, endurance/reliability data per MIL-PRF-38535 Class B, and real-world substitution guidance for legacy system sustainment.
Technical Context
The AT28C256E-20UM/883 implements a paged architecture with a 64-byte internal latching register, enabling simultaneous writes of 1–64 bytes within a single page defined by address bits A6–A14. Its dual-line chip enable (CE) and output enable (OE) control supports bus contention avoidance in multiprocessor systems.
Write operations are protected by VCC sense (inhibit below 3.8 V), 5 ms power-on delay, noise filtering (<15 ns pulse rejection), and optional software data protection (SDP) using a 3-byte command sequence. End-of-write detection is supported via I/O7 DATA polling or I/O6 toggle-bit monitoring.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory capacity | 256 Kbit (32,768 × 8) - provides full byte-addressable nonvolatile storage for firmware boot code or configuration tables |
| Read access time | 200 ns max - meets timing requirements for 5 MHz bus interfaces without wait states |
| Page write cycle | 10 ms max - enables efficient bulk updates while maintaining deterministic worst-case programming latency |
| Endurance | 100,000 write/erase cycles - supports field-updatable mission-critical systems over extended service life |
| Data retention | 10 years at +125°C - validated for long-term reliability in high-temperature avionics and space-qualified enclosures |
| Supply voltage | 5 V ±10% - compatible with standard TTL/CMOS logic rails and eliminates need for auxiliary voltage regulators |
| Operating temperature | −55°C to +125°C - qualified per MIL-PRF-38535 Class B for deployment in extreme environmental conditions |
Pinout & Package
AT28C256E-20UM/883 is supplied in a 30-pin ceramic Pin Grid Array (PGA) package compliant with MIL-STD-1835 U-configuration. Pin 1 is index-marked; pins 1 and 17 are designated "Don't Connect" (DC) and must remain unconnected in PCB layout.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address inputs | 15-bit address bus supporting full 32,768-word addressing; A6–A14 define page boundaries for 64-byte writes |
| I/O0–I/O7 | Bidirectional data bus | True CMOS/TTL-compatible 8-bit data path; I/O7 used for DATA polling, I/O6 for toggle-bit status reporting |
| CE | Chip Enable | Active-low device selection; combined with OE enables three-state output control and bus sharing |
| OE | Output Enable | Active-low read strobe; when high, forces outputs to high-impedance regardless of CE state |
| WE | Write Enable | Active-low write strobe; initiates byte or page write on falling edge; latches address/data internally |
| VCC | Power supply | +5 V ±10% main supply; powers core logic and I/O buffers; includes internal VCC-sense circuitry for write inhibit |
| GND | Ground reference | Signal and power return plane; requires low-inductance connection to minimize noise during write cycles |
| DC (pins 1, 17) | Don't Connect | No internal connection; must be left floating - solder mask coverage recommended to prevent accidental shorts |
Key Features
| Feature | Design Value |
|---|---|
| 64-byte page write buffer | Reduces firmware update time by up to 64× vs. byte-by-byte writes; eliminates host CPU wait states during internal programming |
| DATA Polling (I/O7) | Enables real-time write completion detection without external timing components or interrupts - critical for deterministic real-time OS integration |
| Toggle Bit (I/O6) | Provides asynchronous write status feedback independent of data content - simplifies polling logic in resource-constrained microcontrollers |
| Software Data Protection (SDP) | Prevents inadvertent writes via 3-byte command sequence; remains active across power cycles - essential for flight-critical configuration integrity |
| MIL-PRF-38535 Class B qualification | Guarantees screening, testing, and traceability per military reliability standards including burn-in, temperature cycling, and hermeticity validation |
Applications
| Avionics Flight Control Unit | Tactical Radio Firmware Storage |
|---|---|
Use Scenario: Storing calibrated sensor coefficients and flight envelope limits in a triple-redundant flight computer. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed during power-up initialization and runtime parameter lookup. Use Value: 100,000-cycle endurance ensures >20 years of field updates; −55°C to +125°C operation maintains functionality across stratospheric and desert deployments. |
Use Scenario: Holding encrypted waveform definitions and channel calibration data in a manpack HF/VHF transceiver. IC Role / Device Role / Timing Role: Secure, tamper-resistant storage for mission-critical radio parameters with SDP-enabled write lockout. Use Value: Hardware VCC-sense and 5 ms power-on delay prevent corruption during battery insertion or brownout events. |
| Spacecraft Onboard Computer BIOS | Nuclear Power Plant Safety Controller |
Use Scenario: Boot firmware and watchdog configuration in a radiation-hardened satellite subsystem. IC Role / Device Role / Timing Role: Radiation-tolerant EEPROM providing golden image recovery after single-event upsets. Use Value: Ceramic PGA package offers hermetic sealing and low outgassing; 10-year data retention validated at +125°C supports multi-year orbital missions. |
Use Scenario: Storing reactor trip setpoints and diagnostic history logs in a Class 1E safety-rated controller. IC Role / Device Role / Timing Role: Fail-safe nonvolatile memory with deterministic write completion signaling for ASME NQA-1 compliance. Use Value: DATA polling and toggle-bit methods provide redundant, hardware-verified write status - satisfies IEC 61508 SIL-3 diagnostics requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar paged parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28C256-20UM/883 | Same die, identical military screening and marking; differs only in endurance rating (E = 100K cycles vs. standard 10K) | Required where extended field update count is mandated (e.g., DoD logistics lifecycle >15 years) | Select AT28C256E-20UM/883 when 100K-cycle endurance is contractually specified or required for long-term sustainment planning. |
| DS2502-E48+T&R | 1-Wire interface, 1024-bit EPROM (not EEPROM); no write capability after initial programming; TO-92 package | Used for permanent device ID tagging, not field-updatable storage | Not a functional substitute - DS2502 lacks write capability, page architecture, and parallel bus interface required by AT28C256E-20UM/883 applications. |
Compared with AT28C256E-20UM/883, the standard AT28C256-20UM/883 offers identical timing and interface but lower endurance (10K vs. 100K cycles), making it suitable for static configuration storage; DS2502-E48+T&R is a one-time-programmable serial ID device with no write functionality or parallel bus support.
Availability
AT28C256E-20UM/883 is available at Aetrix Electronics and suitable for avionics flight control units, tactical radio firmware storage, spacecraft onboard computer BIOS, nuclear safety controllers, and other defense/aerospace applications requiring stable component supply under extended lifecycle management.
Supply support for AT28C256E-20UM/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 company specializing in microcontrollers, analog devices, and memory solutions, with deep heritage in military and aerospace component design.
The AT28C256 product line was developed for high-reliability embedded systems requiring radiation-tolerant, long-life nonvolatile memory with deterministic write behavior and robust data protection - targeting defense, space, and nuclear infrastructure markets.
FAQ
What is the endurance rating of the AT28C256E-20UM/883?
The AT28C256E-20UM/883 is rated for 100,000 write/erase cycles, as indicated by the "E" suffix in the part number. This extended endurance is validated per MIL-PRF-38535 Class B testing and supports long-term field updates in mission-critical systems where firmware or calibration data changes frequently over decades of service life. The standard AT28C256-20UM/883 offers 10,000 cycles.
Does the AT28C256E-20UM/883 support both hardware and software write protection?
Yes, the AT28C256E-20UM/883 implements dual-layer protection: hardware features include VCC-sense (write inhibit below 3.8 V), 5 ms power-on delay, WE/CE noise filtering (<15 ns), and CE/OE/WE logic gating; software protection uses a 3-byte command sequence (AAh→55h→A0h) to enable/disable write lockout, which persists across power cycles and is required before any write operation when enabled.
How is write completion detected on the AT28C256E-20UM/883?
Write completion on the AT28C256E-20UM/883 is confirmed via two independent hardware methods: DATA polling monitors I/O7, which returns the complement of the last written byte until completion, then true data; toggle-bit detection observes I/O6, which toggles between 0 and 1 during programming and stabilizes upon completion. Both methods allow host software to avoid fixed delays and respond deterministically.
What package type does the AT28C256E-20UM/883 use, and are all pins connected?
The AT28C256E-20UM/883 uses a 30-pin ceramic Pin Grid Array (PGA) package per MIL-STD-1835 U-configuration. Pins 1 and 17 are designated "Don't Connect" (DC) - they have no internal connection and must remain unconnected in PCB layout. All other pins serve defined address, data, control, or power functions as documented in the official Microchip datasheet DS20006344A.
Is the AT28C256E-20UM/883 compatible with standard TTL/CMOS logic levels?
Yes, the AT28C256E-20UM/883 features CMOS and TTL-compatible inputs and outputs. Input thresholds meet VIH ≥ 2.0 V and VIL ≤ 0.8 V; output drive strength supports VOL ≤ 0.45 V at 2.1 mA sink and VOH ≥ 2.4 V at 400 µA source. This ensures interoperability with legacy 5 V microcontrollers, FPGAs, and ASICs without level-shifting circuitry.
AT28C256E-20UM/883 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-BCPGA
- Packaging:
- Box
- 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-CPGA (13.97x16.51)
AT28C256E-20UM/883 FAQ
1.How can I place an order for AT28C256E-20UM/883 through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28C256E-20UM/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-20UM/883 reliable?
The price and inventory of AT28C256E-20UM/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-20UM/883 is usually 5 days.
3.What payment methods are accepted for AT28C256E-20UM/883?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28C256E-20UM/883 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28C256E-20UM/883?
AT28C256E-20UM/883 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28C256E-20UM/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-20UM/883?
For technical support, including AT28C256E-20UM/883 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28C256E-20UM/883 requirements.
6.How does Aetrix verify that AT28C256E-20UM/883 is sourced from the original manufacturer or authorized distributors?
All AT28C256E-20UM/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-20UM/883 meets industry standards.
7.What is the process for return or replacement of AT28C256E-20UM/883?
All AT28C256E-20UM/883 units undergo pre-shipment inspection (PSI). If there is an issue with AT28C256E-20UM/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-20UM/883 part is unused and in its original packaging.
Return procedure for AT28C256E-20UM/883:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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