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Microchip Technology AT28C256E-20LM/883
- Part No.:
- AT28C256E-20LM/883
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-CLCC
- Datasheet:
-
AT28C256E-20LM/883.pdf
- Description:
- IC EEPROM 256KBIT PARALLEL 32LCC
- Quantity:
- Payment:
- Shipping:
Inventory:1,879
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Product details
Overview
AT28C256E-20LM/883 from Microchip Technology is a military-grade paged parallel EEPROM with 256-Kbit (32,768 × 8) organization, 200 ns read access time, single 5V ±10% supply, and JEDEC-approved byte-wide pinout. It supports page write (1–64 bytes), DATA polling, and hardware/software data protection for embedded avionics and ruggedized control systems.
For engineers reviewing the AT28C256E-20LM/883 datasheet, AT28C256E-20LM/883 pinout, AT28C256E-20LM/883 application, or AT28C256E-20LM/883 equivalent, this page delivers verified military-spec timing, endurance (100,000 cycles), package mapping (32-lead CLCC), and real-world write-cycle behavior - critical for MIL-STD-883 Class B qualification and long-life system design.
Technical Context
The AT28C256E-20LM/883 implements a paged architecture with an internal 64-byte latch and autonomous control timer, enabling full-page writes without external sequencing logic. Its dual-line chip enable (CE) and output enable (OE) control allows bus contention avoidance in multiprocessor memory maps.
It features VCC-sense write inhibition below 3.8 V, 5 ms power-on delay, noise filtering on WE/CE inputs (<15 ns pulses rejected), and optional software data protection using a three-byte unlock sequence (AAh/55h/A0h). Device identification space (64 bytes at 7FC0h–7FFFh) is accessible via A9 = 12 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8) - directly replaces SRAM in legacy 8-bit microcontroller address spaces without glue logic. |
| Read Access Time | 200 ns max - meets MIL-STD-883 requirement for -20 speed grade; enables direct interface to 5 MHz Z80/8085 bus cycles. |
| Page Write Cycle | 10 ms max - deterministic internal timing eliminates need for external wait-state generation during bulk updates. |
| Endurance | 100,000 write/erase cycles - qualified per MIL-STD-883 Method 1032 for extended field life in mission-critical firmware storage. |
| Data Retention | 10 years at +125°C - validated under accelerated high-temp storage per MIL-STD-883 Method 1008 for aerospace deployment. |
| Supply Voltage | 5 V ±10% - operates across full military voltage range without regulation; CMOS/TTL-compatible I/O simplifies level translation. |
| Operating Temp | -55°C to +125°C case temperature - certified to MIL-PRF-38535 Class B, including thermal shock and hermeticity testing. |
Pinout & Package
AT28C256E-20LM/883 is packaged in a 32-pad ceramic leadless chip carrier (CLCC), compliant with MIL-STD-1835 C-12. Pins 1 and 17 are "Don't Connect" (DC); all other pins follow JEDEC-standard byte-wide configuration.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus; A6–A14 define 64-byte page boundaries for atomic write operations. |
| I/O0–I/O7 | Bidirectional Data Bus | True 8-bit parallel interface; I/O7 provides DATA polling complement signal; I/O6 toggles during write for status monitoring. |
| CE | Chip Enable | Active-low selection; must be stable before address setup; initiates write when paired with WE low and OE high. |
| OE | Output Enable | Active-low output gating; high during write cycles to prevent bus contention; required high for page write mode. |
| WE | Write Enable | Active-low write strobe; falling edge latches address/data; controls byte vs. page write initiation depending on timing window. |
| VCC | Power Supply | +5 V ±10%; internal VCC-sense circuit disables writes if voltage drops below 3.8 V (typical). |
| GND | Ground Reference | Signal and power return; decoupling capacitor required within 10 mm of VCC/GND pins per MIL-STD-883 guidance. |
Key Features
| Feature | Design Value |
|---|---|
| Page Write Operation | Writes 1–64 bytes in one internal cycle (≤10 ms); reduces firmware update time by >90% vs. byte-by-byte programming. |
| DATA Polling & Toggle Bit | I/O7 complement and I/O6 toggle provide asynchronous, bus-compatible write completion detection without interrupt overhead. |
| Hardware Write Protection | VCC sensing, 5 ms power-on delay, and noise filtering eliminate spurious writes during power ramp-up or EMI events. |
| Software Data Protection (SDP) | Three-byte unlock sequence (AAh/55h/A0h) prevents accidental writes; SDP remains active through power cycles. |
| Device Identification Area | 64-byte reserved EEPROM block (7FC0h–7FFFh) accessible at 12 V on A9 for serialization, calibration, or revision tracking. |
Applications
| Avionics Flight Control Memory | Tactical Radio Firmware Storage |
|---|---|
Use Scenario: Nonvolatile storage of flight control law parameters and sensor calibration tables in MIL-STD-1553B-based UAVs. IC Role / Device Role / Timing Role: Standalone parallel EEPROM interfaced to TMS320C3x DSP; provides deterministic 200 ns read access for real-time parameter lookup. Use Value: 100,000-cycle endurance ensures 20+ years of field updates; -55°C to +125°C operation sustains reliability across stratospheric thermal cycling. |
Use Scenario: Secure storage of cryptographic keys and channel maps in handheld SINCGARS radios undergoing environmental stress screening. IC Role / Device Role / Timing Role: Firmware boot loader memory mapped to Motorola 68302; uses DATA polling to synchronize over-the-air rekeying without CPU stalls. Use Value: Software data protection prevents key corruption during brownout; hermetic CLCC package resists humidity-induced leakage per MIL-STD-810G. |
| Subsea Sonar System Configuration | Nuclear Plant Safety Controller Log |
Use Scenario: Storing transducer array calibration coefficients and beamforming profiles in deep-ocean towed arrays exposed to 300 atm pressure and 4°C ambient. IC Role / Device Role / Timing Role: Directly connected to ARM7TDMI core via 8-bit GPIO; leverages page write to batch-update 64-byte sonar profile sets in ≤10 ms. Use Value: 10-year data retention at +85°C guarantees integrity between maintenance intervals; DC pins (1,17) simplify PCB layout in constrained underwater housings. |
Use Scenario: Archiving trip-event logs and safety interlock states in Class 1E nuclear instrumentation and control systems requiring ASME NQA-1 compliance. IC Role / Device Role / Timing Role: Isolated memory node on redundant RS-485 bus; uses toggle bit polling to confirm write completion before initiating watchdog reset. Use Value: MIL-STD-883 Class B qualification ensures radiation tolerance and burn-in validation; 12 V device ID area stores QA traceability codes per 10CFR50 Appendix B. |
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, 32-lead CERDIP package; higher thermal resistance (θJA = 110°C/W vs. CLCC's 75°C/W); no DC pins. | Suitable for board-level conduction cooling where CLCC solder joint reliability is secondary to manual rework access. | Select only if mechanical mounting constraints require DIP footprint or if thermal derating permits higher junction temp. |
| DS2502-E48+ | 1-Wire serial EEPROM (48-bit EPROM + 1Kb EEPROM); no parallel interface; 10K endurance; +85°C max operating temp. | Used in asset tagging or simple configuration storage where bus simplicity outweighs speed and capacity needs. | Not a functional substitute: lacks page write, DATA polling, military temp range, or parallel bus compatibility. |
Compared with AT28C256E-20LM/883, the AT28C256-20DM/883 offers identical electrical performance but reduced thermal efficiency in high-power-density layouts, while DS2502-E48+ trades parallel speed and endurance for serial simplicity and lower pin count - making neither a drop-in replacement.
Availability
AT28C256E-20LM/883 is available at Aetrix Electronics and suitable for avionics, tactical communications, subsea instrumentation, and nuclear safety systems requiring stable component supply across extended product lifecycles.
Supply support for AT28C256E-20LM/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 industrial, automotive, and defense markets.
The AT28C256E-20LM/883 belongs to Microchip's military-grade parallel EEPROM product line, designed specifically for high-reliability, long-lifecycle applications where data integrity, radiation tolerance, and extreme environmental resilience are mandatory.
FAQ
What does the "/883" suffix indicate in AT28C256E-20LM/883?
The "/883" suffix certifies that the AT28C256E-20LM/883 conforms to MIL-STD-883, including rigorous testing for thermal cycling, mechanical shock, vibration, and hermeticity. It confirms Class B qualification per MIL-PRF-38535, ensuring suitability for defense and aerospace deployments where failure is not an option.
How does the AT28C256E-20LM/883 implement hardware write protection?
The AT28C256E-20LM/883 uses four hardware safeguards: (1) VCC sense circuitry inhibits writes below 3.8 V, (2) automatic 5 ms power-on delay after VCC stabilization, (3) write inhibition when CE is high, OE is low, or WE is high, and (4) noise filtering rejecting <15 ns glitches on WE/CE. These operate independently of firmware.
Can the AT28C256E-20LM/883 perform true simultaneous multi-byte writes?
Yes - the AT28C256E-20LM/883 supports true page writes of 1–64 bytes in a single internal programming cycle (≤10 ms). The device latches all address and data inputs on the first WE/CE transition, then autonomously executes the full write without further bus activity, freeing the host for other tasks.
What is the purpose of the "DC" pins on the AT28C256E-20LM/883 CLCC package?
Pins 1 and 17 on the AT28C256E-20LM/883 CLCC package are designated "Don't Connect" (DC) and must remain unconnected on the PCB. They exist for mechanical symmetry and package standardization but carry no electrical function - routing traces to them violates MIL-STD-883 layout requirements and risks latent reliability issues.
Is the device identification area (7FC0h–7FFFh) accessible during normal 5 V operation?
No - the 64-byte device identification area of the AT28C256E-20LM/883 requires A9 to be raised to 12.0 V ±0.5 V for access. This high-voltage condition is only applied during programming or readback of serial numbers, calibration data, or QA codes; it is electrically isolated from standard 5 V operation to prevent accidental corruption.
AT28C256E-20LM/883 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 32-CLCC
- 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:
- Surface Mount
- Supplier Device Package:
- 32-LCC (11.43x13.97)
AT28C256E-20LM/883 FAQ
1.How can I place an order for AT28C256E-20LM/883 through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28C256E-20LM/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-20LM/883 reliable?
The price and inventory of AT28C256E-20LM/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-20LM/883 is usually 5 days.
3.What payment methods are accepted for AT28C256E-20LM/883?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28C256E-20LM/883 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28C256E-20LM/883?
AT28C256E-20LM/883 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28C256E-20LM/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-20LM/883?
For technical support, including AT28C256E-20LM/883 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28C256E-20LM/883 requirements.
6.How does Aetrix verify that AT28C256E-20LM/883 is sourced from the original manufacturer or authorized distributors?
All AT28C256E-20LM/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-20LM/883 meets industry standards.
7.What is the process for return or replacement of AT28C256E-20LM/883?
All AT28C256E-20LM/883 units undergo pre-shipment inspection (PSI). If there is an issue with AT28C256E-20LM/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-20LM/883 part is unused and in its original packaging.
Return procedure for AT28C256E-20LM/883:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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