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Microchip Technology AT28HC256F-90TU
- Part No.:
- AT28HC256F-90TU
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-TSSOP (0.465", 11.80mm Width)
- Datasheet:
-
AT28HC256F-90TU.pdf
- Description:
- IC EEPROM 256KBIT PAR 28TSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,314
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Product details
Overview
AT28HC256F-90TU from Microchip Technology is a military-grade 256-Kbit (32,768 × 8) paged parallel EEPROM with 90 ns read access time, 3 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 for nonvolatile configuration storage.
For engineers reviewing the AT28HC256F-90TU datasheet, AT28HC256F-90TU pinout, AT28HC256F-90TU application, or AT28HC256F-90TU equivalent, key selection considerations include military temperature compliance, 3 ms fast page write capability, CMOS/TTL compatibility, hardware VCC-sense write inhibit, and 64-byte internal page register architecture.
Technical Context
The AT28HC256F-90TU implements a paged write architecture with an internal 64-byte latch that accepts up to 64 bytes within 150 µs per byte; A6–A14 define the page address, while A0–A5 select byte positions. Write operations are self-timed using an internal control timer and support both byte and page modes.
End-of-write detection is implemented via DATA polling on I/O7 (complement-to-data during write, true data after completion) and toggle-bit monitoring on I/O6. Hardware protection includes VCC sense (<3.8 V inhibits write), 5 ms power-on delay, noise filtering (<15 ns pulses ignored), and CE/OE/WE logic-level inhibition.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Density | 256 Kbit (32,768 × 8) - supports full system configuration storage without external expansion |
| Read Access Time | 90 ns - enables direct replacement of SRAM in legacy military bus interfaces |
| Page Write Cycle Time | 3 ms max - reduces firmware update latency vs. standard 10 ms variants |
| Operating Temperature | –55°C to +125°C - qualified for MIL-STD-883 Class B environments |
| Supply Voltage | 5 V ±10% - compatible with legacy 5 V TTL/CMOS systems without level shifting |
| Endurance | 10,000 write/erase cycles - sufficient for field-programmable calibration and fault-log storage |
| Data Retention | 10 years - meets long-life deployment requirements for aerospace platforms |
Pinout & Package
AT28HC256F-90TU is supplied in a 32-lead CERDIP package (MIL-STD-1835 D-10 Config A, glass-sealed ceramic). Pin 1 is index corner; pins 1 and 17 are "Don't Connect" (DC); NC pins are unconnected and must remain floating.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus supporting full 32K-word addressing; A6–A14 define page boundaries for 64-byte writes |
| I/O0–I/O7 | Bidirectional Data Bus | Byte-wide parallel interface; I/O7 used for DATA polling, I/O6 for toggle-bit end-of-write detection |
| CE | Chip Enable | Active-low chip select; required low with OE low and WE high for read access |
| OE | Output Enable | Active-low output control; disables outputs to high-Z when high, preventing bus contention |
| WE | Write Enable | Active-low write strobe; initiates byte or page write on falling edge; must be held low ≥100 ns |
| VCC | Power Supply | +5 V ±10% supply; internal VCC sense circuitry inhibits writes below ~3.8 V |
| GND | Ground Reference | Signal and power return; decoupling capacitor required within 10 mm of VCC/GND pins |
Key Features
| Feature | Design Value |
|---|---|
| 64-byte internal page register | Enables burst programming of contiguous memory without re-latching address between bytes |
| Hardware write protection | VCC sense + 5 ms power-on delay prevents corruption during brown-out or cold-start conditions |
| Software data protection (SDP) | Three-byte unlock sequence (AAh/55h/A0h) required before any write-prevents accidental overwrites |
| DATA Polling on I/O7 | Eliminates need for fixed delays or external timers during firmware updates |
| JEDEC-standard pinout | Ensures drop-in compatibility with existing 28-pin parallel EEPROM footprints and PCB layouts |
Applications
| Avionics Configuration Storage | Tactical Radio Firmware Backup |
|---|---|
Use Scenario: Storing flight-critical configuration parameters (e.g., navigation offsets, sensor calibrations) in airborne mission computers. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed at power-up and during in-flight reconfiguration; requires guaranteed retention over 10-year service life. Use Value: Military temperature range and 10,000-cycle endurance ensure reliability under thermal cycling and repeated field updates. | Use Scenario: Preserving encrypted firmware images and cryptographic keys in handheld tactical radios operating in desert or arctic environments. IC Role / Device Role / Timing Role: Secure boot memory holding signed firmware fragments; accessed only during boot or secure OTA update. Use Value: Hardware VCC-sense and software data protection prevent unauthorized or glitch-induced writes during battery transitions. |
| Missile Guidance System Calibration | Subsea Sonar Signal Processing |
Use Scenario: Storing factory-calibrated coefficients for inertial measurement units (IMUs) in guided munitions. IC Role / Device Role / Timing Role: One-time programmable calibration store written during final test; read-only during operational use. Use Value: 10-year data retention and radiation-tolerant CMOS process ensure accuracy remains valid across shelf life and launch stresses. | Use Scenario: Holding real-time adaptive filter coefficients updated during deep-ocean deployment of towed array sonar systems. IC Role / Device Role / Timing Role: Field-updatable coefficient memory interfaced directly to DSP host via parallel bus; updated every 2–4 hours. Use Value: 3 ms page write time minimizes acoustic silence intervals during coefficient refresh, preserving mission continuity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28HC256-90JC | Same core die, but 28-lead CERDIP package with 10 ms write cycle; no "F" fast-write variant | Lacks 3 ms page write performance; suitable only where update speed is non-critical | Select only if legacy board uses 28-pin footprint and military temp range is secondary to cost |
| MX28F256J5F | Intel-compatible 256 Kbit flash; requires sector erase before write; no page register; 55 ns read, 20 ms program | Requires full-sector erase (not byte/page), increasing firmware update complexity and wear | Choose only when migrating to flash-based architecture with erase management firmware already in place |
Compared with AT28HC256F-90TU, AT28HC256-90JC trades faster write performance for legacy 28-pin compatibility, while MX28F256J5F replaces EEPROM simplicity with flash density and longer endurance at the cost of erase overhead and timing unpredictability.
Availability
AT28HC256F-90TU is available at Aetrix Electronics and suitable for avionics control modules, tactical radio firmware backup, and missile guidance calibration requiring stable component supply across extended military lifecycle programs.
Supply support for AT28HC256F-90TU 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 manufacturer specializing in microcontrollers, analog devices, and nonvolatile memory solutions for industrial, automotive, and defense markets.
The AT28HC256F-90TU belongs to Microchip's military-grade parallel EEPROM product line, designed specifically for high-reliability, long-life applications in harsh environments where data integrity and guaranteed retention are critical.
FAQ
What is the maximum page write size supported by the AT28HC256F-90TU?
The AT28HC256F-90TU supports up to 64 bytes per page write operation. All bytes must reside on the same page, defined by address bits A6–A14. Each successive byte must be loaded within 150 µs of the prior one; exceeding this interval triggers automatic internal programming. This capability is confirmed in Section 6.8 and Figure 6.9 of the DS20006352A datasheet for the AT28HC256F-90TU.
Does the AT28HC256F-90TU require external high-voltage programming signals?
No, the AT28HC256F-90TU operates from a single 5 V ±10% supply and does not require external 12 V or other high-voltage programming signals for normal byte or page writes. Only optional chip erase (Section 6.10) or device identification memory access (Section 6) requires 12 V on A9. All standard AT28HC256F-90TU read/write functions execute at 5 V.
How is write completion detected on the AT28HC256F-90TU?
Write completion on the AT28HC256F-90TU is detected using either DATA polling on I/O7 (complement of written data appears during write; true data returns upon completion) or toggle-bit monitoring on I/O6 (toggles between 0 and 1 during write; stabilizes when complete). Both methods are fully supported and characterized in Sections 6.14–6.17 of the AT28HC256F-90TU datasheet.
Is the AT28HC256F-90TU pin-compatible with standard 28-pin parallel EEPROMs?
No, the AT28HC256F-90TU uses a 32-lead CERDIP package with JEDEC-standard byte-wide pinout, not a 28-pin footprint. Its pin count and layout match 32-pin industry standards (e.g., 32-lead CLCC, Flatpack), not legacy 28-pin devices. The AT28HC256F-90TU datasheet explicitly lists 32-lead CERDIP as its package type, and pin mapping differs significantly from 28-pin variants like AT28HC256-90JC.
What hardware write protection mechanisms are built into the AT28HC256F-90TU?
The AT28HC256F-90TU includes four hardware write protection mechanisms: (1) VCC sense circuitry that inhibits writes below ~3.8 V, (2) 5 ms internal power-on delay before write enable, (3) write inhibition when CE is high, OE is low, or WE is high, and (4) noise filtering rejecting input pulses <15 ns. These are documented in Section 6 of the AT28HC256F-90TU datasheet under "Hardware Protection".
AT28HC256F-90TU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-TSSOP (0.465", 11.80mm Width)
- Packaging:
- Tray
- 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:
- 3ms
- Access Time:
- 90 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
AT28HC256F-90TU FAQ
1.How can I place an order for AT28HC256F-90TU through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28HC256F-90TU 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 AT28HC256F-90TU reliable?
The price and inventory of AT28HC256F-90TU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28HC256F-90TU is usually 5 days.
3.What payment methods are accepted for AT28HC256F-90TU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28HC256F-90TU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28HC256F-90TU?
AT28HC256F-90TU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28HC256F-90TU 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 AT28HC256F-90TU?
For technical support, including AT28HC256F-90TU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28HC256F-90TU requirements.
6.How does Aetrix verify that AT28HC256F-90TU is sourced from the original manufacturer or authorized distributors?
All AT28HC256F-90TU 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 AT28HC256F-90TU meets industry standards.
7.What is the process for return or replacement of AT28HC256F-90TU?
All AT28HC256F-90TU units undergo pre-shipment inspection (PSI). If there is an issue with AT28HC256F-90TU, 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 AT28HC256F-90TU part is unused and in its original packaging.
Return procedure for AT28HC256F-90TU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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