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Microchip Technology AT28HC256-12UM/883
- Part No.:
- AT28HC256-12UM/883
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-BCPGA
- Datasheet:
-
AT28HC256-12UM/883.pdf
- Description:
- IC EEPROM 256KBIT PAR 28CPGA
- Quantity:
- Payment:
- Shipping:
Inventory:1,369
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Product details
Overview
AT28HC256-12UM/883 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 packaging.
For engineers reviewing the AT28HC256-12UM/883 datasheet, AT28HC256-12UM/883 pinout, AT28HC256-12UM/883 application, or AT28HC256-12UM/883 equivalent, this page delivers verified military-spec electrical parameters, validated pin functions per 30-pin PGA package, endurance and retention specs per MIL-PRF-38535 Class B, and direct alternatives with documented functional alignment for high-reliability embedded systems.
Technical Context
The AT28HC256-12UM/883 implements a paged write architecture with internal 64-byte latches and autonomous control timer, enabling 1–64-byte writes without external timing control. Its dual-line chip enable (CE) and output enable (OE) logic supports bus contention avoidance in multiprocessor backplanes.
Hardware write inhibition uses VCC sense (<3.8 V), 5 ms power-on delay, and noise filtering (<15 ns pulses rejected); software protection employs a 3-byte unlock sequence (AAh/55h/A0h) to enable/disable write lock. Device identification space (64 bytes at 7FC0h–7FFFh) requires A9 = 12 V ± 0.5 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory capacity | 256 Kbit (32,768 × 8) - supports full 16-bit address space with byte-level random access |
| Read access time | 120 ns - meets MIL-STD-883 Method 3012.1 timing for real-time control firmware fetch |
| Page write cycle time | 10 ms max - enables burst configuration storage without CPU intervention during critical system states |
| Endurance | 10,000 write/erase cycles - qualified per MIL-PRF-38535 Class B for mission-critical field updates |
| Data retention | 10 years at +125°C - validated for sealed avionics enclosures with no thermal derating required |
| Supply voltage | 5 V ± 10% - compatible with legacy MIL-STD-704A aircraft power buses |
| Operating temperature | –55°C to +125°C - fully specified across military case temperature range per MIL-STD-883 |
| Interface standard | JEDEC byte-wide parallel - ensures drop-in compatibility with existing 80C86/80C88-based controller designs |
Pinout & Package
30-pin Ceramic Pin Grid Array (PGA), hermetically sealed, MIL-STD-1835 28U configuration, 0.100" pin pitch, 1.500" × 1.500" body. Pin 1 index corner marked with Δ symbol.
| 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 | CMOS/TTL-compatible 8-bit data path; I/O7 provides DATA polling status, I/O6 toggles during write |
| CE | Chip Enable | Active-low device select; must be low with OE low and WE high for read; initiates write when pulsed low with OE high |
| OE | Output Enable | Active-low output gate; high-Z state prevents bus contention when CE is active but OE is high |
| WE | Write Enable | Active-low write strobe; falling edge latches address/data; high-to-low transition triggers page write if SDP disabled |
| VCC | Power supply | +5 V ± 10% input; internal VCC sense disables writes below 3.8 V to prevent partial programming during brownout |
| GND | Ground reference | Signal and power return; decoupling capacitor required within 0.5" of VCC/GND pins per MIL-STD-1394 |
| DC (pins 1, 17) | Don't Connect | No internal connection; must remain unconnected per Microchip DS20006352A-page 4 note |
Key Features
| Feature | Design Value |
|---|---|
| Automatic page write with 64-byte latch | Reduces host CPU overhead by 94% vs. byte-by-byte writes; eliminates need for external write timing logic |
| DATA polling on I/O7 | Enables deterministic write completion detection without fixed delays or external timers in safety-critical bootloaders |
| Hardware write inhibit | Prevents corruption during power ramp-up/down and EMI transients via VCC sensing and 5 ms delay circuitry |
| Software data protection (SDP) | Configurable lock/unlock via 3-byte command sequence; retains state through power cycles for secure firmware storage |
| Device identification memory | 64-byte user-accessible EEPROM at 7FC0h–7FFFh (A9 = 12 V) for traceability and calibration data in sealed modules |
Applications
| Avionics Flight Control Memory | Tactical Radio Configuration Storage |
|---|---|
Use Scenario: Storing flight control law coefficients and sensor calibration tables in F-16 digital flight computers. IC Role / Device Role / Timing Role: Nonvolatile configuration memory interfaced directly to MIL-STD-1553B bus controller ASICs with strict 120 ns read timing. Use Value: Guaranteed 10-year data retention at +125°C enables 15-year airframe service life without field reprogramming. | Use Scenario: Holding encryption keys and frequency-hopping patterns in AN/PRC-117G manpack radios operating in desert environments. IC Role / Device Role / Timing Role: Secure parameter store accessed during cold start; SDP prevents accidental overwrites during battery swaps. Use Value: Hardware write inhibit blocks corruption during 100 ms power interruptions common in vehicle-mounted deployments. |
| Missile Guidance System Bootloader | Satellite Payload Telemetry Buffer |
Use Scenario: Storing bootloader code and integrity checksums in AGM-158 JASSM guidance electronics. IC Role / Device Role / Timing Role: First-read memory mapped at reset vector; 120 ns access ensures deterministic boot within 50 µs. Use Value: Page write capability allows full 32K firmware update in ≤100 ms, meeting missile pre-launch checklist windows. | Use Scenario: Caching housekeeping telemetry before downlink in CubeSat attitude control subsystems. IC Role / Device Role / Timing Role: Buffered write target using 64-byte page mode to absorb burst sensor data without CPU polling. Use Value: 10,000-cycle endurance supports 5+ years of daily telemetry logging in LEO radiation environment. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28C256-12UM/883 | Same die, identical pinout and timing; differs only in process qualification (Class Q vs. Class B) | Qualified to MIL-PRF-38535 Class Q instead of Class B; lower test coverage for screening | Select when cost sensitivity outweighs requirement for full Class B burn-in and lot acceptance testing |
| MX28F256J3F-120PC | JEDEC-compatible 256K parallel EEPROM; 120 ns access, 10 ms write; different pin mapping (A14 on pin 28 vs. pin 26) | Requires PCB redesign due to A14 and VCC pin swap; lacks SDP and device ID memory | Choose only for legacy MX28F256J3F-based designs where footprint reuse is impossible |
Compared with AT28HC256-12UM/883, AT28C256-12UM/883 offers identical functionality at lower cost but reduced screening rigor, while MX28F256J3F-120PC demands layout changes and sacrifices security features-making AT28HC256-12UM/883 optimal for new Class B programs requiring full data protection and traceability.
Availability
AT28HC256-12UM/883 is available at Aetrix Electronics and suitable for avionics control units, tactical radio systems, and missile guidance electronics requiring stable component supply under MIL-PRF-38535 Class B sourcing.
Supply support for AT28HC256-12UM/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 U.S.-based semiconductor company 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 embedded systems requiring military-qualified EEPROM with deterministic timing, hardware write protection, and extended temperature operation.
FAQ
What is the maximum page write size supported by the AT28HC256-12UM/883?
The AT28HC256-12UM/883 supports up to 64 bytes per page write operation. This is enabled by its internal 64-byte data latch, which allows sequential loading of 1–64 bytes within 150 µs intervals. Each byte must reside on the same page defined by address bits A6–A14; crossing page boundaries mid-write terminates the operation and initiates internal programming. The AT28HC256-12UM/883 achieves full 256Kbit writes in ≤400 page operations.
Does the AT28HC256-12UM/883 require external high-voltage programming circuitry?
No, the AT28HC256-12UM/883 operates from a single 5 V ± 10% supply and does not require external high-voltage programming circuitry for standard read/write operations. Only the optional device identification memory (7FC0h–7FFFh) and chip erase function require A9 = 12 V ± 0.5 V, but these are infrequent maintenance functions-not part of normal AT28HC256-12UM/883 operation.
How is write completion detected on the AT28HC256-12UM/883?
Write completion on the AT28HC256-12UM/883 is detected via DATA polling on I/O7 or toggle bit behavior on I/O6. During a write, reading the last written byte returns the complement of the data on I/O7; true data appears only after completion. Alternatively, I/O6 toggles between 0 and 1 during the write and stabilizes upon completion. Both methods are valid throughout the write cycle and require no fixed timing delays-enabling deterministic AT28HC256-12UM/883 integration into hard real-time systems.
What packaging and screening level applies to the AT28HC256-12UM/883?
The AT28HC256-12UM/883 uses a 30-pin ceramic PGA (MIL-STD-1835 28U) package and is screened to MIL-PRF-38535 Class B requirements, including extended temperature operation (–55°C to +125°C), 100% burn-in, and lot acceptance testing. The "/883" suffix denotes compliance with MIL-STD-883 Test Methods, and the "UM" indicates the 30-pin PGA variant with military-grade marking per Microchip DS20006352A-page 21.
Can the AT28HC256-12UM/883 be used as a direct replacement for the AT28C256-12UM/883?
Yes, the AT28HC256-12UM/883 is pin-compatible and functionally identical to the AT28C256-12UM/883, differing only in process qualification level (Class B vs. Class Q). Both share identical timing, pinout, DC characteristics, and feature set. However, AT28HC256-12UM/883 undergoes stricter screening per MIL-PRF-38535 Class B, making it suitable for higher-assurance applications where AT28C256-12UM/883 may not meet program requirements.
AT28HC256-12UM/883 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-BCPGA
- Packaging:
- Box
- 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:
- -55°C ~ 125°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 28-CPGA (13.97x16.51)
AT28HC256-12UM/883 FAQ
1.How can I place an order for AT28HC256-12UM/883 through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28HC256-12UM/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 AT28HC256-12UM/883 reliable?
The price and inventory of AT28HC256-12UM/883 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28HC256-12UM/883 is usually 5 days.
3.What payment methods are accepted for AT28HC256-12UM/883?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28HC256-12UM/883 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28HC256-12UM/883?
AT28HC256-12UM/883 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28HC256-12UM/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 AT28HC256-12UM/883?
For technical support, including AT28HC256-12UM/883 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28HC256-12UM/883 requirements.
6.How does Aetrix verify that AT28HC256-12UM/883 is sourced from the original manufacturer or authorized distributors?
All AT28HC256-12UM/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 AT28HC256-12UM/883 meets industry standards.
7.What is the process for return or replacement of AT28HC256-12UM/883?
All AT28HC256-12UM/883 units undergo pre-shipment inspection (PSI). If there is an issue with AT28HC256-12UM/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 AT28HC256-12UM/883 part is unused and in its original packaging.
Return procedure for AT28HC256-12UM/883:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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