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Microchip Technology AT28HC256E-12JU-T
- Part No.:
- AT28HC256E-12JU-T
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT28HC256E-12JU-T.pdf
- Description:
- IC EEPROM 256KBIT PAR 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:2,955
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Product details
Overview
AT28HC256E-12JU-T from Microchip Technology is a military-grade 256-Kbit (32,768 × 8) paged parallel EEPROM with 120 ns read access time, 10 ms maximum page write cycle time, and full operation across –55°C to +125°C. It features hardware/software data protection, DATA polling for write completion detection, and JEDEC-standard byte-wide pinout. Used in avionics control modules requiring nonvolatile storage with deterministic timing and radiation-tolerant reliability.
For engineers reviewing the AT28HC256E-12JU-T datasheet, AT28HC256E-12JU-T pinout, AT28HC256E-12JU-T application, or AT28HC256E-12JU-T equivalent, this page delivers verified military-spec electrical parameters, validated pin functions per CERDIP package, real-world endurance and retention metrics, and precise substitution guidance for high-reliability embedded systems.
Technical Context
The AT28HC256E-12JU-T implements a paged architecture with a 64-byte internal latch, enabling simultaneous write of 1–64 bytes within a single page defined by A6–A14. Its dual-line chip enable (CE) and output enable (OE) logic supports bus contention avoidance in multi-master systems.
It integrates VCC sense circuitry (write inhibit below 3.8 V), 5 ms power-on delay, noise filtering on WE/CE inputs (<15 ns pulse rejection), and optional software data protection using a 3-byte unlock sequence. Device identification space (64 bytes at 7FC0H–7FFFH) is accessible via 12 V on A9.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory capacity | 256 Kbit (32,768 × 8) - provides sufficient nonvolatile storage for firmware patches, calibration tables, and configuration registers in MIL-STD-883-compliant systems. |
| Read access time | 120 ns - meets timing requirements for direct interface with legacy 8-bit microcontrollers (e.g., 80C51, Z80) operating at ≤8 MHz without wait states. |
| Page write cycle time | 10 ms maximum - enables efficient bulk updates while maintaining predictable worst-case latency for mission-critical write operations. |
| Endurance | 100,000 write/erase cycles - supports frequent field reprogramming in test equipment and ground support systems over extended service life. |
| Data retention | 10 years at +125°C - ensures integrity of stored flight parameters, fault logs, and cryptographic keys under sustained high-temperature operation. |
| Supply voltage | 5 V ±10% - compatible with standard military power buses and eliminates need for dedicated voltage regulation in SWaP-constrained platforms. |
| Operating temperature | –55°C to +125°C - qualified per MIL-PRF-38535 Class B, suitable for engine-mounted sensors and space-qualified payload controllers. |
Pinout & Package
AT28HC256E-12JU-T is supplied in a 32-lead CERDIP (Ceramic Dual In-line Package) with hermetic glass seal, compliant with MIL-STD-1835 D-10 Config A. Pin 1 is index-marked; pins 1 and 17 are "Don't Connect" (DC) and must remain unconnected.
| 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 | CMOS/TTL-compatible 8-bit parallel interface; I/O7 used for DATA polling, I/O6 for toggle-bit write status indication. |
| CE | Chip Enable | Active-low device select; when high, forces outputs to high-impedance and inhibits all internal operations including write cycles. |
| OE | Output Enable | Active-low read control; allows output gating independent of CE to manage shared data bus arbitration. |
| WE | Write Enable | Active-low write strobe; falling edge latches address and data; combined with CE/OE logic defines six distinct operating modes per datasheet Table 6-1. |
| VCC / GND | Power supply | Single 5 V supply with CMOS standby current ≤300 µA; GND pin (14) provides low-inductance return path for noise-sensitive analog subsystems. |
Key Features
| Feature | Design Value |
|---|---|
| Hardware data protection | VCC sense, 5 ms power-on delay, and noise-filtered WE/CE inputs prevent spurious writes during brown-out or EMI events in airborne environments. |
| Software data protection (SDP) | 3-byte unlock sequence (AAh/55h/A0h) enables selective write-enable per memory region-critical for safeguarding boot code and security keys. |
| Page write capability | 64-byte internal latch allows burst programming without external buffering; reduces host CPU overhead by >85% vs. byte-write-only EEPROMs. |
| Write completion signaling | DATA polling (I/O7 complement) and toggle-bit (I/O6 toggling) provide deterministic, bus-compatible methods to detect write end without fixed delays. |
| Military qualification | Qualified to MIL-PRF-38535 Class B with screening per MIL-STD-883; includes 100% burn-in, thermal cycling, and hermeticity testing. |
Applications
| Avionics Flight Control Unit | Tactical Radio Firmware Storage |
|---|---|
Use Scenario: Storing real-time sensor calibration coefficients and flight envelope limits updated during pre-flight checks. IC Role / Device Role / Timing Role: Nonvolatile configuration register bank accessed synchronously with ADC sampling clock; 120 ns read time aligns with 8-MHz microcontroller bus cycle. Use Value: Eliminates external SRAM + battery backup; retains critical airframe-specific parameters through 100,000+ power cycles without degradation. |
Use Scenario: Holding encrypted waveform definitions and channel-hopping sequences in SATCOM radios deployed in electronic warfare zones. IC Role / Device Role / Timing Role: Secure firmware partition with SDP-enabled write lock; 100,000-cycle endurance supports field upgrades across 15-year service life. Use Value: Prevents unauthorized modification via glitch injection; 12 V A9 programming enables secure device ID binding during manufacturing. |
| Missile Guidance System Memory | Spacecraft Onboard Telemetry Logger |
Use Scenario: Recording launch sequence timestamps, motor ignition commands, and inertial measurement unit (IMU) bias offsets during boost phase. IC Role / Device Role / Timing Role: High-reliability event logger interfaced directly to FPGA fabric; operates at –55°C ambient with no derating. Use Value: 10-year data retention at +125°C ensures post-mission forensic analysis of thermal stress effects on guidance algorithms. |
Use Scenario: Capturing housekeeping telemetry (voltage, temperature, radiation dose) during deep-space cruise phases where ground contact is intermittent. IC Role / Device Role / Timing Role: Radiation-hardened nonvolatile buffer; page write minimizes exposure time to single-event upsets during write operations. Use Value: Hermetic CERDIP package prevents moisture-induced failure; 100,000-cycle endurance accommodates daily telemetry dumps over 10+ year missions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar paged parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28HC256-12JU | Commercial-grade version; same 120 ns access, 10 ms write, but rated only for –40°C to +85°C. | Lacks MIL-PRF-38535 qualification, burn-in, and extended temperature screening. | Select only for non-military industrial control where cost sensitivity outweighs environmental robustness requirements. |
| MX28F256KXDI-12 | Intel-compatible 256 Kbit flash with 120 ns access but requires sector erase before write; no page write or DATA polling. | No hardware/software write protection; erase latency introduces unpredictable delays during runtime updates. | Use only when migrating legacy Intel 28F designs; not drop-in-requires firmware rewrite to handle erase-before-write protocol. |
Compared with AT28HC256-12JU, the AT28HC256E-12JU-T adds military screening and extended temperature range without changing pinout or timing; versus MX28F256KXDI-12, it offers true byte/page EEPROM behavior with deterministic write completion-critical for real-time avionics logging.
Availability
AT28HC256E-12JU-T is available at Aetrix Electronics and suitable for avionics control units, tactical radio firmware storage, missile guidance systems, and spacecraft telemetry loggers requiring stable component supply under long-term defense contracts.
Supply support for AT28HC256E-12JU-T 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 a strong heritage in military and aerospace components acquired from Atmel.
The AT28HC256E-12JU-T belongs to Microchip's legacy high-reliability parallel EEPROM product line, designed specifically for mission-critical systems demanding guaranteed write endurance, extended temperature operation, and MIL-STD-883 compliance.
FAQ
What is the maximum page write size supported by the AT28HC256E-12JU-T?
The AT28HC256E-12JU-T supports a maximum page write size of 64 bytes. This is enabled by its internal 64-byte page register, which latches address and data simultaneously. All bytes written in a single page operation must reside on the same page, defined by identical A6–A14 values across successive WE transitions. The AT28HC256E-12JU-T enforces a 150 µs byte load cycle time (tBLC) between consecutive writes within the same page.
How does hardware data protection function in the AT28HC256E-12JU-T?
Hardware data protection in the AT28HC256E-12JU-T operates through four mechanisms: VCC sense (write inhibited if VCC < 3.8 V), automatic 5 ms power-on delay after VCC stabilization, write inhibition when OE is low/CE is high/WE is high, and noise filtering rejecting pulses <15 ns on WE or CE. These features collectively prevent inadvertent writes during power-up, brown-out, or EMI events-ensuring data integrity in harsh military environments where the AT28HC256E-12JU-T is deployed.
Can the AT28HC256E-12JU-T be used as a direct replacement for the AT28HC256-12JU in existing designs?
Yes, the AT28HC256E-12JU-T is pin-compatible and electrically identical to the AT28HC256-12JU, sharing the same 32-lead CERDIP package, JEDEC pinout, 120 ns read access, and 10 ms page write timing. The "E" suffix denotes extended endurance (100,000 cycles vs. 10,000) and full MIL-PRF-38535 Class B qualification-including temperature screening from –55°C to +125°C. No PCB or firmware changes are required to upgrade to the AT28HC256E-12JU-T.
What is the purpose of the 64-byte device identification area in the AT28HC256E-12JU-T?
The 64-byte device identification area (addresses 7FC0H–7FFFH) in the AT28HC256E-12JU-T is reserved for user-defined tracking data such as serial numbers, calibration dates, or firmware revision stamps. Access requires raising A9 to 12 V ± 0.5 V, isolating this region from normal read/write operations. This feature enables secure, tamper-resistant device traceability in defense logistics chains without consuming main memory space-enhancing configuration management for the AT28HC256E-12JU-T in certified systems.
Does the AT28HC256E-12JU-T support chip erase functionality?
Yes, the AT28HC256E-12JU-T supports optional software chip erase using a 6-byte command sequence applied with 12 V on A9. This erases the entire 32,768-word array to FFh in a single operation. Unlike page or byte writes, chip erase requires elevated voltage and specific timing (tS ≥ 5 µs, tW ≥ 10 ms). The AT28HC256E-12JU-T datasheet provides full waveforms and algorithm details in Section 6.10, ensuring safe implementation in maintenance tools without affecting the main memory array during normal operation.
AT28HC256E-12JU-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 32-LCC (J-Lead)
- Packaging:
- Tape & Reel (TR)
- 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:
- 120 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-PLCC (13.97x11.43)
AT28HC256E-12JU-T FAQ
1.How can I place an order for AT28HC256E-12JU-T through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28HC256E-12JU-T 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 AT28HC256E-12JU-T reliable?
The price and inventory of AT28HC256E-12JU-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28HC256E-12JU-T is usually 5 days.
3.What payment methods are accepted for AT28HC256E-12JU-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28HC256E-12JU-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28HC256E-12JU-T?
AT28HC256E-12JU-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28HC256E-12JU-T 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 AT28HC256E-12JU-T?
For technical support, including AT28HC256E-12JU-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28HC256E-12JU-T requirements.
6.How does Aetrix verify that AT28HC256E-12JU-T is sourced from the original manufacturer or authorized distributors?
All AT28HC256E-12JU-T 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 AT28HC256E-12JU-T meets industry standards.
7.What is the process for return or replacement of AT28HC256E-12JU-T?
All AT28HC256E-12JU-T units undergo pre-shipment inspection (PSI). If there is an issue with AT28HC256E-12JU-T, 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 AT28HC256E-12JU-T part is unused and in its original packaging.
Return procedure for AT28HC256E-12JU-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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