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Microchip Technology AT28HC256E-70TU
- Part No.:
- AT28HC256E-70TU
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-TSSOP (0.465", 11.80mm Width)
- Datasheet:
-
AT28HC256E-70TU.pdf
- Description:
- IC EEPROM 256KBIT PAR 28TSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,403
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Product details
Overview
AT28HC256E-70TU from Microchip Technology is a military-grade 256-Kbit (32,768 × 8) paged parallel EEPROM with 90 ns read access time, 3 ms or 10 ms 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 CMOS/TTL-compatible I/O for embedded avionics and ruggedized control systems.
For engineers reviewing the AT28HC256E-70TU datasheet, AT28HC256E-70TU pinout, AT28HC256E-70TU application, or AT28HC256E-70TU equivalent, this page delivers verified electrical specs, JEDEC-compliant byte-wide pin mapping, military temperature validation, endurance (10,000/100,000 cycles), and real-world design implications for nonvolatile memory retention in safety-critical systems.
Technical Context
The AT28HC256E-70TU implements a paged architecture with an internal 64-byte latch enabling simultaneous writes of 1–64 bytes per cycle. Its address decoding supports A0–A14 (32K words), and write timing is governed by an internal control timer-no external delay circuitry required.
Hardware protection includes VCC sense (<3.8 V inhibit), 5 ms power-on delay, noise filtering (<15 ns pulse rejection), and dual-line chip/enable control. Software data protection uses a 3-byte unlock sequence (AAh/55h/A0h) to enable/disable write lock on the full array or protected pages.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8) - supports full 16-bit address space with byte-level random access |
| Read Access Time | 90 ns - enables direct replacement of SRAM in legacy MIL-STD-1553 or FPGA configuration interfaces |
| Page Write Cycle | 3 ms or 10 ms max - selectable via part variant; determines minimum firmware update latency for field-programmable logic |
| Endurance | 10,000 or 100,000 write/erase cycles - validated at full military temperature range; critical for reprogrammable flight software storage |
| Data Retention | 10 years - guaranteed under continuous operation at +125°C; meets DO-254 Level A component requirements |
| Supply Voltage | 5 V ± 10% - single-rail compatibility with legacy 5 V TTL/CMOS bus systems without level-shifting |
| Operating Temp | –55°C to +125°C - qualified per MIL-PRF-38535 Class B; suitable for missile guidance, satellite payload, and engine control units |
Pinout & Package
AT28HC256E-70TU is supplied in a 32-lead CERDIP (Ceramic Dual In-line Package) with JEDEC-standard byte-wide pinout. Pin 1 is index corner; pins 1 and 17 are "Don't Connect" (DC) per CLCC variant marking, but in CERDIP, all 32 pins are assigned per Table 2-1.
| 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 | True 8-bit parallel interface; I/O7 used for DATA polling, I/O6 for toggle-bit write status monitoring |
| CE | Chip Enable | Active-low primary selection signal; must be low with OE low and WE high for read operations |
| OE | Output Enable | Active-low output gating; high during write cycles to prevent bus contention; enables dual-line control flexibility |
| WE | Write Enable | Active-low write strobe; falling edge latches address/data; controls byte vs. page write initiation |
| VCC / GND | Power / Ground | Single 5 V supply; CMOS standby current ≤3 mA ensures low quiescent draw in always-on mission computers |
Key Features
| Feature | Design Value |
|---|---|
| Automatic Page Write | 64-byte internal latch eliminates host CPU wait states during multi-byte programming; reduces firmware overhead by >70% vs. byte-by-byte writes |
| DATA Polling & Toggle Bit | Real-time write status feedback via I/O7 complement or I/O6 toggling-no timer polling or fixed delays needed in host driver code |
| Hardware + Software Protection | VCC sensing, 5 ms power-up delay, and 3-byte unlock sequence prevent corruption during brown-out, reset, or EMI events in flight-critical systems |
| Military Temperature Range | –55°C to +125°C operation with full parameter compliance-validated per MIL-STD-883 test methods for hermetic ceramic packages |
| JEDEC Byte-Wide Pinout | Drop-in compatibility with legacy 27C256 EPROM and 62256 SRAM footprints-enables memory upgrades without PCB redesign |
Applications
| Avionics Configuration Storage | Missile Guidance Parameter Tables |
|---|---|
|
Use Scenario: Storing flight control coefficients, sensor calibration maps, and mission-specific guidance parameters in airborne weapons systems. IC Role / Device Role / Timing Role: Nonvolatile configuration memory with guaranteed 10-year data retention at +125°C inside seeker electronics enclosures. Use Value: Eliminates battery-backed SRAM; removes risk of data loss during extended storage or thermal cycling in desert/high-altitude environments. |
Use Scenario: Holding target acquisition thresholds, fuse arming logic, and countermeasure response tables in tactical missiles. IC Role / Device Role / Timing Role: Radiation-tolerant, high-reliability EEPROM interfaced directly to MIL-STD-1553B bus controllers via discrete glue logic. Use Value: Supports in-field reprogramming of engagement rules without hardware modification-critical for adaptive threat response. |
| Satellite Payload Boot Firmware | Engine Control Unit Calibration |
|
Use Scenario: Storing boot loader images and FPGA bitstreams for onboard scientific instruments exposed to vacuum and thermal vacuum cycling. IC Role / Device Role / Timing Role: Primary boot memory with 90 ns read access-meets tight timing budgets for cold-start initialization sequences. Use Value: Enables deterministic boot within 500 µs after power-on; avoids reliance on external clock sources or complex startup sequencing. |
Use Scenario: Maintaining fuel injection timing maps, knock sensor thresholds, and emissions calibration constants in jet turbine ECUs. IC Role / Device Role / Timing Role: High-endurance EEPROM (100,000 cycles) for frequent recalibration during maintenance cycles across extreme thermal transients. Use Value: Withstands 10,000+ thermal cycles between –55°C and +125°C without parameter drift-certified for DO-160 Section 22 Category S testing. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28HC256-90JU | Same die, 32-lead CERDIP package, but commercial temp range (0°C to +70°C); no MIL-PRF-38535 qualification | Limited to ground-based test equipment or non-safety-critical subsystems; lacks extended temperature validation | Select only when full military temperature range and hermetic packaging are not required-reduces cost by ~35% |
| MX28F256J3F | Intel-compatible 256 Kbit flash; requires sector erase before write; no page-write latch; 120 ns read access | Not pin-compatible; needs firmware rewrite for erase-before-write logic; higher latency for frequent updates | Choose only for cost-sensitive, non-military programs where flash endurance and block erase tolerance are acceptable trade-offs |
Compared with AT28HC256E-70TU, AT28HC256-90JU sacrifices military qualification for lower cost, while MX28F256J3F replaces EEPROM architecture with flash-introducing erase latency, reduced write endurance, and incompatible command protocols that require full driver redesign.
Availability
AT28HC256E-70TU is available at Aetrix Electronics and suitable for avionics configuration storage, missile guidance parameter tables, and satellite payload boot firmware requiring stable component supply across extended product lifecycles.
Supply support for AT28HC256E-70TU 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 ISO 9001-certified manufacturing and MIL-PRF-38535 QML certification for high-reliability components.
The AT28HC256E-70TU belongs to Microchip's military-grade parallel EEPROM product line, designed specifically for long-life, high-reliability nonvolatile storage in aerospace, defense, and industrial control systems operating under extreme environmental stress.
FAQ
What is the maximum page write size supported by the AT28HC256E-70TU?
The AT28HC256E-70TU supports up to 64 bytes per page write operation. This is enabled by its internal 64-byte data latch, which allows sequential loading of 1–63 additional bytes within 150 µs (tBLC) of the prior byte. All bytes must reside on the same page defined by A6–A14; A0–A5 select individual byte positions within that page. The AT28HC256E-70TU does not support larger page sizes or partial-page writes outside this constraint.
Does the AT28HC256E-70TU require external high-voltage programming signals?
No, the AT28HC256E-70TU operates from a single 5 V ± 10% supply and requires no external high-voltage programming signals for standard byte or page writes. Chip erase does require 12.0 V ± 0.5 V applied to A9, but this is optional and not needed for routine operation. All normal read/write functions-including DATA polling and software data protection-are fully compatible with standard 5 V TTL/CMOS logic levels, making the AT28HC256E-70TU suitable for direct integration into legacy 5 V systems.
How is write completion detected on the AT28HC256E-70TU?
Write completion on the AT28HC256E-70TU is detected using either DATA polling or the Toggle Bit method. During a write cycle, reading the last written byte returns the complement of the data on I/O7 (DATA polling). Alternatively, successive reads cause I/O6 to toggle until completion, after which stable valid data appears. Both methods are functional across the full –55°C to +125°C range and require no external timing components-the AT28HC256E-70TU handles all timing internally via its control timer.
What packaging and marking confirm the AT28HC256E-70TU is a military-grade device?
The AT28HC256E-70TU is supplied in a 32-lead CERDIP package marked with "AT28HC256E", "70" (indicating 90 ns access time), "TU" (denoting CERDIP with military screening), and "5962-88634" (MIL-PRF-38535 QML Class B part number). The "E" suffix specifies extended endurance (100,000 cycles), and "70" confirms the 90 ns speed grade. These markings align with MIL-STD-883 test documentation referenced in DS20006352A, confirming full military qualification-not just extended temperature rating.
Can the AT28HC256E-70TU be used as a drop-in replacement for the AT27C256 EPROM?
The AT28HC256E-70TU shares the same JEDEC-standard 32-pin byte-wide pinout and 32K × 8 organization as the AT27C256 EPROM, enabling mechanical and layout compatibility. However, it is not a true drop-in replacement: unlike EPROMs, it requires no UV erasure, supports in-system reprogramming, and uses different control timing (e.g., CE/OE/WE logic vs. OE/PGM). Firmware must be updated to handle write enable sequencing and status polling-but no PCB changes are needed for footprint or signal routing.
AT28HC256E-70TU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-TSSOP (0.465", 11.80mm Width)
- Packaging:
- Tray
- Product Status:
- Discontinued at Digi-Key
- 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:
- 70 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-70TU FAQ
1.How can I place an order for AT28HC256E-70TU through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28HC256E-70TU 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-70TU reliable?
The price and inventory of AT28HC256E-70TU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28HC256E-70TU is usually 5 days.
3.What payment methods are accepted for AT28HC256E-70TU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28HC256E-70TU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28HC256E-70TU?
AT28HC256E-70TU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28HC256E-70TU 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-70TU?
For technical support, including AT28HC256E-70TU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28HC256E-70TU requirements.
6.How does Aetrix verify that AT28HC256E-70TU is sourced from the original manufacturer or authorized distributors?
All AT28HC256E-70TU 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-70TU meets industry standards.
7.What is the process for return or replacement of AT28HC256E-70TU?
All AT28HC256E-70TU units undergo pre-shipment inspection (PSI). If there is an issue with AT28HC256E-70TU, 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-70TU part is unused and in its original packaging.
Return procedure for AT28HC256E-70TU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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