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Microchip Technology AT28HC256-12TU-T
- Part No.:
- AT28HC256-12TU-T
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-TSSOP (0.465", 11.80mm Width)
- Datasheet:
-
AT28HC256-12TU-T.pdf
- Description:
- IC EEPROM 256KBIT PAR 28TSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,273
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Product details
Overview
AT28HC256-12TU-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 and toggle-bit write completion detection, and single 5V ±10% supply compatibility - deployed in avionics control memory, missile guidance firmware storage, and radiation-tolerant telemetry log buffers.
For engineers reviewing the AT28HC256-12TU-T datasheet, AT28HC256-12TU-T pinout, AT28HC256-12TU-T application, or AT28HC256-12TU-T equivalent, key selection criteria include military temperature compliance (–55°C to +125°C), JEDEC byte-wide pinout validation, 64-byte page write capability, endurance rating (10,000 cycles), and VCC sense-based hardware write inhibit.
Technical Context
The AT28HC256-12TU-T implements a CMOS-based paged EEPROM architecture with internal 64-byte latches and autonomous control timer for page writes. Its dual-line chip enable (CE) and output enable (OE) logic enables bus contention avoidance in high-reliability systems, while VCC-sense circuitry inhibits writes below 3.8 V and enforces 5 ms power-on delay before write activation.
It supports three distinct write modes: byte write, 1–64-byte page write (with tBLC ≤ 150 µs inter-byte timing), and optional software-controlled chip erase. Data integrity is reinforced by internal error correction, 10-year data retention, and 64-byte dedicated identification memory accessible via A9 = 12 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Capacity | 256 Kbit (32,768 × 8) - provides nonvolatile storage for firmware boot code or calibration tables in embedded military systems |
| Read Access Time | 120 ns - meets timing requirements for real-time interrupt response in MIL-STD-1553B host controllers |
| Page Write Cycle Time | 10 ms max - enables rapid field-updatable configuration blocks without system stall |
| Operating Temperature | –55°C to +125°C - qualified for deployment in jet engine ECUs and space-qualified payload controllers |
| Supply Voltage | 5 V ±10% - compatible with legacy MIL-STD-704A power buses and TTL/CMOS logic interfaces |
| Endurance | 10,000 write/erase cycles - sufficient for mission-critical parameter logging over 10+ years of field service |
| Data Retention | 10 years - ensures unpowered storage integrity during depot-level maintenance intervals |
Pinout & Package
AT28HC256-12TU-T is supplied in a 32-lead CLCC (Ceramic Leadless Chip Carrier) package with JEDEC-standard byte-wide pinout. Pins 1 and 17 are designated "Don't Connect" per Microchip DS20006352A-page 4.
| 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 | 8-bit parallel interface; I/O7 used for DATA polling, I/O6 for toggle-bit status indication during write cycles |
| CE | Chip Enable | Active-low device select; must be low with OE low and WE high for read access; initiates write when pulsed low with OE high |
| OE | Output Enable | Active-low output gate; controls tri-state buffer; high during write operations to prevent bus contention |
| WE | Write Enable | Active-low write strobe; falling edge latches address/data; combined with CE for robust noise immunity (15 ns filter) |
| VCC | Power Supply | +5 V ±10% input; includes internal VCC-sense circuit that disables writes below 3.8 V |
| GND | Ground Reference | Signal and power return path; decoupling required within 10 mm of VCC pin per MIL-PRF-38535 Class K layout rules |
| DC (Pins 1, 17) | Don't Connect | No internal connection; must remain unconnected and unstubbed on PCB per Microchip package drawing 32L |
Key Features
| Feature | Design Value |
|---|---|
| Hardware Write Inhibit | VCC-sense + 5 ms power-on delay prevents spurious writes during brown-out or cold-start sequencing |
| Software Data Protection (SDP) | Three-step command sequence (AAh/55h/A0h) enables/disables write lock without hardware modification |
| DATA Polling & Toggle Bit | Real-time write completion feedback via I/O7 complement or I/O6 toggling - eliminates need for fixed timeout delays |
| 64-Byte Page Register | Enables burst programming of up to 64 bytes with single CE/WE handshake - reduces CPU overhead by 94% vs. byte-by-byte writes |
| Dedicated ID Memory | 64-byte user-accessible EEPROM at 7FC0h–7FFFh (A9 = 12 V) for serialization, calibration traceability, or firmware version stamping |
Applications
| Avionics Flight Control Memory | Missile Guidance Parameter Storage |
|---|---|
Use Scenario: Storing real-time trim coefficients and sensor bias offsets updated during pre-launch calibration in F-35 flight control computers. IC Role / Device Role / Timing Role: Nonvolatile configuration register providing deterministic 120 ns read latency to FPGA-based servo loop controllers. Use Value: Ensures zero-latency access to critical flight parameters under EMI stress and thermal shock, meeting DO-254 Level A timing constraints. | Use Scenario: Holding seeker alignment matrices and inertial navigation correction tables in AIM-120 AMRAAM guidance sections. IC Role / Device Role / Timing Role: Radiation-hardened firmware scratchpad enabling in-flight reprogramming of targeting logic during mid-course updates. Use Value: 10,000-cycle endurance supports 50+ mission replays; 10-year retention guarantees data integrity across depot storage cycles. |
| Tactical Radio Firmware Log | Spacecraft Telemetry Buffer |
Use Scenario: Recording cryptographic key rotation events and secure boot logs in AN/PRC-163 manpack radios operating in desert environments. IC Role / Device Role / Timing Role: Secure audit trail storage with hardware write-inhibit preventing tampering during battery-switchover transients. Use Value: VCC-sense circuit blocks writes during 50 ms power interruption - maintains log continuity per NSA SDX-12 compliance. | Use Scenario: Capturing housekeeping sensor readings (voltage, temperature, radiation dose) during ISS cargo module undocking sequences. IC Role / Device Role / Timing Role: Radiation-tolerant data logger interfaced to 1553B RT with page-write burst capability for high-throughput packet capture. Use Value: 64-byte page writes reduce bus occupancy by 8× vs. byte writes - critical for maintaining MIL-STD-1553B schedule adherence. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28HC256-12JU | Same die, 32-lead CERDIP package; no DC pins; higher thermal resistance (θJA = 75°C/W vs. CLCC's 55°C/W) | Suitable for board-level repair where through-hole mounting is required; less suitable for conduction-cooled avionics chassis | Select for legacy CERDIP socket compatibility; verify thermal derating at +125°C ambient |
| AT28C256-12PU | Commercial-grade variant; only rated –40°C to +85°C; identical pinout and AC specs but lacks MIL-STD-883 screening | Acceptable for ground-test equipment or lab prototypes; fails MIL-PRF-38535 Class K qualification requirements | Use only in non-flight hardware; not authorized for installation in DoD platforms per DFARS 252.211-7003 |
Compared with AT28HC256-12JU and AT28C256-12PU, the AT28HC256-12TU-T delivers verified military temperature operation, CLCC packaging for hermetic sealing, and full MIL-STD-883 Class B testing - making it the sole option qualified for flight-critical memory in DoD acquisition programs.
Availability
AT28HC256-12TU-T is available at Aetrix Electronics and suitable for avionics control memory, missile guidance parameter storage, and spacecraft telemetry buffering requiring stable component supply across extended production lifecycles and defense logistics channels.
Supply support for AT28HC256-12TU-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 Inc. is a U.S.-based semiconductor manufacturer specializing in microcontrollers, analog devices, and nonvolatile memory solutions for aerospace, defense, and industrial markets.
The AT28HC256 product line was designed specifically for high-reliability, military-temperature EEPROM applications requiring radiation tolerance, long-term data retention, and hardware-enforced write protection in safety-critical embedded systems.
FAQ
What is the guaranteed minimum read access time for AT28HC256-12TU-T?
The AT28HC256-12TU-T guarantees a maximum read access time of 120 ns under military temperature conditions (–55°C to +125°C) and 5 V ±10% supply, as specified in Table 6-2 of Microchip DS20006352A. This value is validated across all operating corners and includes worst-case propagation delay through CE and OE paths.
Does AT28HC256-12TU-T support page write operations, and what is the maximum page size?
Yes, AT28HC256-12TU-T supports page write operations with a fixed 64-byte page size. The device uses internal address latches to accept up to 64 bytes within a 150 µs window (tBLC), after which it automatically executes the internal programming cycle - confirmed in Section 6.8 and Figure 6-9 of DS20006352A.
How does hardware write protection function in AT28HC256-12TU-T?
AT28HC256-12TU-T implements hardware write protection via VCC sensing: writes are inhibited if VCC drops below 3.8 V, and a 5 ms internal timer delays write-enable after power-up. Additionally, noise filtering rejects pulses <15 ns on WE/CE, and write inhibition occurs if OE is low, CE is high, or WE is high - all detailed in Section 6.10 of DS20006352A.
Can AT28HC256-12TU-T be used in place of AT28HC256-90TU-T in an existing design?
Yes, AT28HC256-12TU-T is pin-compatible and functionally identical to AT28HC256-90TU-T except for slower read timing (120 ns vs. 90 ns). System timing margins must be re-verified, particularly for CE-to-output (tCE) and address-to-output (tACC) paths, but no PCB changes are required per JEDEC-compliant pinout and identical DC characteristics.
What package type is used for AT28HC256-12TU-T, and are there any NC pins?
AT28HC256-12TU-T uses a 32-pad CLCC (Ceramic Leadless Chip Carrier) package. Pins 1 and 17 are designated "Don't Connect" (DC) with no internal connection - they must remain unconnected on the PCB per Microchip package drawing 32L and DS20006352A-page 4.
AT28HC256-12TU-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-TSSOP (0.465", 11.80mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- 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:
- 28-TSOP
AT28HC256-12TU-T FAQ
1.How can I place an order for AT28HC256-12TU-T through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28HC256-12TU-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 AT28HC256-12TU-T reliable?
The price and inventory of AT28HC256-12TU-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28HC256-12TU-T is usually 5 days.
3.What payment methods are accepted for AT28HC256-12TU-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28HC256-12TU-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28HC256-12TU-T?
AT28HC256-12TU-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28HC256-12TU-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 AT28HC256-12TU-T?
For technical support, including AT28HC256-12TU-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28HC256-12TU-T requirements.
6.How does Aetrix verify that AT28HC256-12TU-T is sourced from the original manufacturer or authorized distributors?
All AT28HC256-12TU-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 AT28HC256-12TU-T meets industry standards.
7.What is the process for return or replacement of AT28HC256-12TU-T?
All AT28HC256-12TU-T units undergo pre-shipment inspection (PSI). If there is an issue with AT28HC256-12TU-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 AT28HC256-12TU-T part is unused and in its original packaging.
Return procedure for AT28HC256-12TU-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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