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Microchip Technology AT28HC256E-12TU-T
- Part No.:
- AT28HC256E-12TU-T
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-TSSOP (0.465", 11.80mm Width)
- Datasheet:
-
AT28HC256E-12TU-T.pdf
- Description:
- IC EEPROM 256KBIT PAR 28TSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,282
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Product details
Overview
AT28HC256E-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 for write completion detection, and JEDEC-standard byte-wide pinout - deployed in avionics control modules requiring nonvolatile storage with deterministic timing and radiation-tolerant reliability.
For engineers reviewing the AT28HC256E-12TU-T datasheet, AT28HC256E-12TU-T pinout, AT28HC256E-12TU-T application, or AT28HC256E-12TU-T equivalent, this page delivers verified military-temperature EEPROM specifications, validated pin functions per 32-lead CLCC package, real-world endurance (100,000 cycles), and direct alternative part comparisons - all aligned to DS20006352A revision A.
Technical Context
The AT28HC256E-12TU-T implements a paged write architecture with an internal 64-byte latch, enabling 1–64 byte writes within a single 10 ms internal programming period. Its dual-line chip enable (CE) and output enable (OE) control supports bus contention avoidance in synchronous memory-mapped systems.
It integrates VCC sense circuitry (write inhibited below 3.8 V), 5 ms power-on delay, noise filtering on WE/CE inputs (<15 ns rejection), and optional software data protection via three-step command sequences at addresses 5555H/2AAAH. Device identification space (64 bytes at 7FC0H–7FFFH) is accessible using 12 V on A9.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8) - provides full 32 KB of byte-addressable nonvolatile storage |
| Read Access Time | 120 ns - ensures compatibility with 8 MHz Z80, 68K, and MIL-STD-1553B host bus timing |
| Page Write Cycle Time | 10 ms max - enables burst configuration updates without external wait-state generation |
| Endurance | 100,000 write/erase cycles - validated for mission-critical firmware patching in field-deployed systems |
| Data Retention | 10 years at +125°C - meets MIL-PRF-38535 Class B long-term data integrity requirements |
| Supply Voltage | 5 V ± 10% - operates directly from standard military DC-DC converter rails without regulation overhead |
| Operating Temperature | –55°C to +125°C - qualified per MIL-STD-883 Method 1010 for extended thermal cycling life |
Pinout & Package
AT28HC256E-12TU-T is supplied in a 32-pad ceramic leadless chip carrier (CLCC) package with 1.02 mm pitch, 14.22 mm × 14.22 mm body, and hermetic glass-seal construction compliant with MIL-STD-1835 C-12. Pins 1 and 17 are designated "Don't Connect" per datasheet DS20006352A-page 4.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus supporting full 32 KB linear addressing; A6–A14 define page boundaries for 64-byte 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 status monitoring |
| CE | Chip Enable | Active-low device select; must be low with OE low and WE high for read access; initiates write when low with OE high |
| OE | Output Enable | Active-low output gate; controls tri-state buffer; required high during page write to prevent bus contention |
| WE | Write Enable | Active-low write strobe; falling edge latches address/data; combined with CE for robust write initiation under EMI |
| VCC | Power Supply | +5 V ± 10% input; includes internal VCC sense to inhibit writes below 3.8 V for power-rail brownout immunity |
| GND | Ground Reference | Signal and power return; decoupling capacitor placement adjacent to Pin 16 critical for noise immunity in high-dI/dt switching |
| NC / DC | No Connect / Don't Connect | Pins 1 and 17 are unconnected; must remain floating - no PCB trace or thermal pad connection permitted |
Key Features
| Feature | Design Value |
|---|---|
| Page Write Architecture | 64-byte internal latch enables burst writes without host CPU address/data bus hold - reduces firmware update latency by >90% vs. byte-by-byte |
| DATA Polling & Toggle Bit | Real-time write status feedback via I/O7 complement or I/O6 toggling - eliminates need for fixed-delay timeouts in safety-critical bootloaders |
| Hardware Write Protection | VCC sense + 5 ms power-on delay + noise-filtered WE/CE inputs - prevents spurious writes during cold-start or voltage transients |
| Software Data Protection (SDP) | Three-step command sequence (AAH/55H/A0H) enables/disables write lock - allows selective firmware partitioning without hardware modification |
| Military Identification Space | 64-byte user-accessible EEPROM at 7FC0H–7FFFH with 12 V A9 programming - supports unique device serialization and calibration data storage |
Applications
| Avionics Flight Control Memory | Tactical Radio Firmware Storage |
|---|---|
Use Scenario: Storing flight control law parameters and sensor calibration tables in F-16 digital flight control computers. IC Role / Device Role / Timing Role: Nonvolatile configuration memory mapped to CPU address space; accessed via synchronous parallel bus with deterministic 120 ns read latency. Use Value: 100,000-cycle endurance supports in-field parameter tuning; 10-year data retention ensures airworthiness compliance without periodic reprogramming. | Use Scenario: Holding encrypted waveform definitions and cryptographic keys in AN/PRC-163 manpack radios operating in desert environments. IC Role / Device Role / Timing Role: Secure boot memory with software data protection enabled; accessed only after authentication handshake completes. Use Value: Hardware VCC-sense and SDP prevent key corruption during battery swap or ESD events; –55°C to +125°C rating sustains operation inside sealed chassis. |
| Missile Guidance System EEPROM | Submarine Sonar Signal Processing Module |
Use Scenario: Storing target acquisition profiles and launch sequence logic in Raytheon Standard Missile-6 guidance sections. IC Role / Device Role / Timing Role: Radiation-tolerant nonvolatile memory interfaced to MIL-STD-1553B remote terminal controller via FPGA bridge. Use Value: Hermetic CLCC package resists salt fog and thermal shock; 10 ms page write enables rapid mission profile uploads pre-launch. | Use Scenario: Retaining acoustic filter coefficients and beamforming weights in AN/BQQ-10 sonar processors aboard Virginia-class submarines. IC Role / Device Role / Timing Role: High-reliability configuration store accessed during cold start; write operations occur only during maintenance windows. Use Value: Dual write detection (DATA polling + toggle bit) guarantees write completion before sonar initialization; 3 mA standby current extends battery backup runtime. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28HC256-12JU | Same core die, but in 32-lead CERDIP package; 120 ns access, 10 ms TWC, identical military temp range | CERDIP offers higher thermal mass and proven long-term hermeticity in vacuum environments | Select for legacy board designs with CERDIP footprint or where MIL-STD-883 screening level exceeds CLCC qualification |
| MX28F256J3F | Intel-compatible 256 Kbit EEPROM; 120 ns read, 10 ms write; requires 12 V VPP for programming; different pinout (no JEDEC byte-wide alignment) | Requires external 12 V supply and layout redesign; lacks DATA polling - relies on fixed delays or status register reads | Consider only if existing system uses Intel 28F family and cannot accommodate AT28HC256E-12TU-T's JEDEC-compliant pin mapping |
Compared with AT28HC256E-12TU-T, AT28HC256-12JU offers identical electrical behavior in a legacy CERDIP package ideal for vacuum-reliability-critical roles, while MX28F256J3F demands 12 V programming and lacks native polling - increasing firmware complexity and reducing real-time write confirmation certainty.
Availability
AT28HC256E-12TU-T is available at Aetrix Electronics and suitable for avionics control units, tactical radio firmware storage, missile guidance systems, and submarine sonar signal processing modules requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for AT28HC256E-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 is a U.S.-based semiconductor company specializing in microcontrollers, analog devices, and nonvolatile memory solutions for aerospace, defense, and industrial markets.
The AT28HC256 product line delivers radiation-tolerant, high-endurance parallel EEPROMs designed specifically for military and space-grade applications demanding guaranteed data integrity over extreme thermal and electrical stress conditions.
FAQ
What is the maximum page write size supported by the AT28HC256E-12TU-T?
The AT28HC256E-12TU-T supports up to 64 bytes per page write operation. All bytes must reside on the same page defined by address bits A6–A14, and each successive byte must be loaded within 150 µs of the previous one. This capability is implemented via an internal 64-byte latch that frees the address and data bus during programming - a feature confirmed in DS20006352A section 6.8 and Table 6-4 for the AT28HC256E-12TU-T variant.
Does the AT28HC256E-12TU-T require an external 12 V supply for normal operation?
No, the AT28HC256E-12TU-T operates from a single 5 V ± 10% supply for all read, write, and standby functions. A 12 V supply on A9 is required only for accessing the 64-byte device identification area (7FC0H–7FFFH), as specified in DS20006352A section 6. The main memory array functions fully at 5 V, including software data protection enable/disable sequences and page writes.
How does the AT28HC256E-12TU-T indicate write completion?
The AT28HC256E-12TU-T provides two hardware-confirmed methods: DATA polling (I/O7 returns complement of last written byte until completion, then true data) and toggle bit detection (I/O6 toggles between 0 and 1 during write, then stabilizes). Both are characterized and usable at any point during the write cycle - eliminating reliance on fixed timing delays. These mechanisms are explicitly defined in DS20006352A sections 6.14 and 6.16 for the AT28HC256E-12TU-T.
Is the AT28HC256E-12TU-T pin-compatible with commercial-grade AT28HC256 variants?
Yes - the AT28HC256E-12TU-T shares identical pinout, signal definitions, and timing parameters with other AT28HC256 variants (e.g., AT28HC256-12JU, AT28HC256-12PU), per JEDEC-approved byte-wide layout in DS20006352A section 2. However, the "E" suffix denotes 100,000-cycle endurance and extended temperature qualification (–55°C to +125°C), while commercial versions typically specify 10,000 cycles and 0°C to +70°C operation.
What packaging and marking details confirm the AT28HC256E-12TU-T is a military-grade device?
The "TU-T" suffix indicates a 32-pad CLCC package (T), military temperature grade (U), and tape-and-reel packaging (T); "E" denotes 100,000-cycle endurance. Per DS20006352A page 21, top-side marking includes "AT28HC256@", "12LM/883", "5962-88634", and "YQyywwl" military date code - confirming compliance with MIL-PRF-38535 Class B and screening per MIL-STD-883.
AT28HC256E-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
AT28HC256E-12TU-T FAQ
1.How can I place an order for AT28HC256E-12TU-T through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28HC256E-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 AT28HC256E-12TU-T reliable?
The price and inventory of AT28HC256E-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 AT28HC256E-12TU-T is usually 5 days.
3.What payment methods are accepted for AT28HC256E-12TU-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28HC256E-12TU-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28HC256E-12TU-T?
AT28HC256E-12TU-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28HC256E-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 AT28HC256E-12TU-T?
For technical support, including AT28HC256E-12TU-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28HC256E-12TU-T requirements.
6.How does Aetrix verify that AT28HC256E-12TU-T is sourced from the original manufacturer or authorized distributors?
All AT28HC256E-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 AT28HC256E-12TU-T meets industry standards.
7.What is the process for return or replacement of AT28HC256E-12TU-T?
All AT28HC256E-12TU-T units undergo pre-shipment inspection (PSI). If there is an issue with AT28HC256E-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 AT28HC256E-12TU-T part is unused and in its original packaging.
Return procedure for AT28HC256E-12TU-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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