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Microchip Technology AT28C256E-25LM/883
- Part No.:
- AT28C256E-25LM/883
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-CLCC
- Datasheet:
-
AT28C256E-25LM/883.pdf
- Description:
- IC EEPROM 256KBIT PARALLEL 32LCC
- Quantity:
- Payment:
- Shipping:
Inventory:4,479
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Product details
Overview
AT28C256E-25LM/883 from Microchip Technology is a military-grade paged parallel EEPROM with 256-Kbit (32,768 × 8) organization, 250 ns read access time, single 5V ±10% supply operation, and JEDEC-approved byte-wide pinout. It supports page write (1–64 bytes), DATA polling, and hardware/software data protection for embedded avionics and defense systems requiring nonvolatile storage with high reliability.
For engineers reviewing the AT28C256E-25LM/883 datasheet, AT28C256E-25LM/883 pinout, AT28C256E-25LM/883 application, or AT28C256E-25LM/883 equivalent, this page delivers verified military-spec electrical characteristics, MIL-STD-883-compliant packaging details, page write timing constraints, endurance (100,000 cycles), and software data protection enable/disable sequences - all confirmed against DS20006344A.
Technical Context
The AT28C256E-25LM/883 implements a CMOS-based paged architecture with internal 64-byte latches and autonomous control timer, enabling simultaneous multi-byte writes without external timing circuitry. Its dual-line chip enable (CE) and output enable (OE) logic provides bus contention control in shared-memory systems.
It features VCC sense (write inhibit below 3.8 V), 5 ms power-on delay, noise filtering on WE/CE inputs (<15 ns pulse rejection), and optional 12 V–based chip erase. The device includes 64 bytes of dedicated identification memory accessible via A9 = 12 V and addresses 7FC0H–7FFFH.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory size | 256 Kbit (32,768 × 8) - supports full 16-bit address space with byte-level random access |
| Read access time | 250 ns max - meets MIL-STD-883 Class B timing for real-time system boot code retrieval |
| Page write cycle | 10 ms max - enables burst programming of up to 64 bytes per internal cycle, reducing host CPU overhead |
| Endurance | 100,000 write/erase cycles - validated for mission-critical firmware update cycles in field-deployed systems |
| Data retention | 10 years at −55°C to +125°C - guaranteed under full military temperature range per MIL-PRF-38535 |
| Supply voltage | 5 V ±10% - compatible with legacy TTL/CMOS logic families without level-shifting circuitry |
| Standby current | 300 µA CMOS - enables low-power hold mode in battery-backed subsystems |
Pinout & Package
AT28C256E-25LM/883 is supplied in a 32-pad ceramic leadless chip carrier (CLCC) package compliant with MIL-STD-1835 C-12, with pins 1 and 17 designated "Don't Connect" per datasheet DS20006344A-page 4. Pinout matches JEDEC-standard byte-wide configuration.
| 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 page writes |
| I/O0–I/O7 | Bidirectional data bus | True 8-bit parallel interface; I/O7 used for DATA polling, I/O6 for toggle-bit write completion detection |
| CE | Chip Enable | Active-low primary selection signal; must be low with OE low and WE high for read operations |
| OE | Output Enable | Active-low output gate; controls tri-state buffer to prevent bus contention during shared-memory access |
| WE | Write Enable | Active-low write strobe; falling edge latches address/data; high-to-low transitions initiate byte or page writes |
| VCC / GND | Power / Ground | Single 5 V supply with CMOS-compatible quiescent current; GND pin (16) serves as reference for all I/O and control signals |
Key Features
| Feature | Design Value |
|---|---|
| Page write with internal latching | Reduces host processor intervention: up to 64 bytes written per command without re-addressing or external timing |
| DATA polling on I/O7 | Enables deterministic write completion detection without fixed delays - critical for hard real-time interrupt service routines |
| Software data protection (SDP) | Prevents accidental writes via 3-byte unlock sequence (AAh/55h/A0h); remains active across power cycles |
| Hardware write inhibition | Combines VCC sensing, 5 ms power-up delay, and noise filtering to eliminate spurious writes during brown-out or EMI events |
| Dedicated ID memory | 64 bytes at 7FC0H–7FFFH accessible with A9 = 12 V - supports traceability, calibration data, or firmware version stamping |
Applications
| Avionics Boot Memory | Tactical Radio Firmware Storage |
|---|---|
Use Scenario: Stores boot loader and FPGA configuration bitstream in MIL-STD-1553B-equipped flight control computers. IC Role / Device Role / Timing Role: Nonvolatile program memory accessed during cold start; requires guaranteed 250 ns read timing and radiation-tolerant data retention. Use Value: Eliminates need for external wait-state generators due to deterministic 250 ns access; 100,000-cycle endurance supports in-field reprogramming of mission profiles. |
Use Scenario: Holds encrypted waveform definitions and channel calibration tables in handheld SINCGARS radios operating at −40°C to +71°C. IC Role / Device Role / Timing Role: Secure parameter storage with software data protection enabled to prevent corruption during battery swaps or voltage transients. Use Value: SDP lock prevents unauthorized firmware modification; 12 V chip erase allows secure field reset without removing the device. |
| Missile Guidance System EEPROM | Submarine Sonar Signal Processing Module |
Use Scenario: Retains target acquisition algorithms and launch parameters in inertial navigation units subjected to 20 g shock and thermal cycling. IC Role / Device Role / Timing Role: High-reliability nonvolatile memory qualified to MIL-PRF-38535 Class B; operates over −55°C to +125°C with 10-year data retention. Use Value: Ceramic CLCC package ensures hermeticity and mechanical stability; 300 µA standby current extends battery life in dormant launch readiness mode. |
Use Scenario: Stores adaptive beamforming coefficients and acoustic signature templates in underwater acoustic processing racks. IC Role / Device Role / Timing Role: Page-write capable memory interfaced to TI C6748 DSP via EMIF; uses DATA polling to synchronize coefficient updates without CPU polling loops. Use Value: 64-byte page writes reduce update latency by >85% vs. byte-by-byte programming; toggle-bit detection provides alternative write-status feedback path. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar paged parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28C256-25JU | Commercial-grade (0°C to +70°C), 32-pin PLCC package, no MIL-STD-883 screening | Lacks radiation tolerance, extended temperature range, and hermetic sealing - unsuitable for aerospace deployment | Select only for cost-sensitive ground-test fixtures or lab prototypes where military qualification is not required |
| MX28LV256A-25G | 3.3 V core supply (with 5 V I/O tolerance), 256 Kbit, 250 ns access, TSOP-32 package | Requires level translation for 5 V systems; lower standby current (100 µA) but unqualified for military temp range | Consider for new designs targeting lower power and smaller footprint, provided voltage compatibility and qualification requirements are met |
Compared with AT28C256E-25LM/883, AT28C256-25JU sacrifices environmental robustness for cost, while MX28LV256A-25G shifts to 3.3 V operation and forfeits MIL-STD-883 compliance - neither offers drop-in replacement capability in certified military platforms.
Availability
AT28C256E-25LM/883 is available at Aetrix Electronics and suitable for avionics boot memory, tactical radio firmware storage, missile guidance system EEPROM, submarine sonar signal processing modules, and other defense electronics requiring stable component supply under MIL-PRF-38535 Class B conditions.
Supply support for AT28C256E-25LM/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 nonvolatile memory solutions, with a strong heritage in military and aerospace components acquired through Atmel.
The AT28C256 product line was originally developed by Atmel and continues under Microchip to serve high-reliability embedded systems requiring paged parallel EEPROM with MIL-STD-883 qualification and extended temperature operation.
FAQ
What is the maximum page write cycle time for AT28C256E-25LM/883?
The maximum page write cycle time for AT28C256E-25LM/883 is 10 ms, as specified in Table 6-4 of DS20006344A. This applies to the E-grade (100,000-cycle endurance) variant and is validated under full military temperature range (−55°C to +125°C). The AT28C256E-25LM/883 does not support the 3 ms fast-write mode found in the F-grade variant.
How is software data protection enabled on AT28C256E-25LM/883?
Software data protection on AT28C256E-25LM/883 is enabled by writing three specific bytes to designated addresses: AAh to 5555h, 55h to 2AAAh, then A0h to 5555h. After this sequence, all subsequent writes require repeating the unlock sequence. The AT28C256E-25LM/883 ships with SDP disabled, and the feature remains active across power cycles until explicitly disabled using the 55h/2AAAh/80h/55h/2AAAh/20h sequence.
Which package type does AT28C256E-25LM/883 use, and what are its key mechanical features?
AT28C256E-25LM/883 uses a 32-pad ceramic leadless chip carrier (CLCC) package per MIL-STD-1835 C-12. Key features include hermetic ceramic construction, leadless terminations for high-frequency stability, and "Don't Connect" designation for pins 1 and 17. The package is screened to MIL-STD-883 Method 5005 for vibration, shock, and thermal cycling, ensuring reliability in high-G and wide-temperature environments.
Does AT28C256E-25LM/883 support chip erase, and how is it performed?
Yes, AT28C256E-25LM/883 supports optional software chip erase using a 6-byte command sequence applied with A9 = 12.0 V ± 0.5 V. The sequence initiates erasure of the entire 32,768-word array and is detailed in Section 6.10 of DS20006344A. Erase time is 10 ms minimum; the device returns to normal operation upon completion, with all locations containing FFh.
What is the purpose of the 64-byte identification memory in AT28C256E-25LM/883?
The 64-byte identification memory in AT28C256E-25LM/883 resides at addresses 7FC0H–7FFFH and is accessed by raising A9 to 12 V ± 0.5 V. It is intended for user-defined data such as serial numbers, calibration coefficients, firmware revision stamps, or manufacturing trace codes - providing permanent, field-programmable identity storage separate from main memory.
AT28C256E-25LM/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:
- 250 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-25LM/883 FAQ
1.How can I place an order for AT28C256E-25LM/883 through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28C256E-25LM/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-25LM/883 reliable?
The price and inventory of AT28C256E-25LM/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-25LM/883 is usually 5 days.
3.What payment methods are accepted for AT28C256E-25LM/883?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28C256E-25LM/883 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28C256E-25LM/883?
AT28C256E-25LM/883 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28C256E-25LM/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-25LM/883?
For technical support, including AT28C256E-25LM/883 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28C256E-25LM/883 requirements.
6.How does Aetrix verify that AT28C256E-25LM/883 is sourced from the original manufacturer or authorized distributors?
All AT28C256E-25LM/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-25LM/883 meets industry standards.
7.What is the process for return or replacement of AT28C256E-25LM/883?
All AT28C256E-25LM/883 units undergo pre-shipment inspection (PSI). If there is an issue with AT28C256E-25LM/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-25LM/883 part is unused and in its original packaging.
Return procedure for AT28C256E-25LM/883:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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