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Microchip Technology AT28HC256E-70JU
- Part No.:
- AT28HC256E-70JU
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT28HC256E-70JU.pdf
- Description:
- IC EEPROM 256KBIT PAR 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:334
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Product details
Overview
AT28HC256E-70JU from Microchip Technology is a 256-Kbit (32,768 × 8) parallel EEPROM with 70 ns read access time, single 5V ±10% supply operation, and industrial temperature range (–40°C to +85°C). It supports hardware/software data protection, DATA polling and toggle-bit write completion detection, and is used in firmware storage, configuration memory, and calibration data retention in embedded control systems.
For engineers reviewing the AT28HC256E-70JU datasheet, AT28HC256E-70JU pinout, AT28HC256E-70JU application, or AT28HC256E-70JU equivalent, this page delivers verified electrical specs, JEDEC-compliant byte-wide pin mapping, page-write timing (≤10 ms), endurance (100,000 cycles), and green PLCC-32 packaging details - all confirmed from Microchip's official DS20006428B.
Technical Context
The AT28HC256E-70JU implements a CMOS-based parallel EEPROM architecture with internal 64-byte page latches and autonomous write timing. Its dual-line chip enable (CE) and output enable (OE) logic enables bus contention avoidance in shared-memory systems, while VCC sense and noise filtering provide hardware-level write inhibition below 3.8 V or for pulses <15 ns.
It features two write completion detection methods: DATA Polling on I/O7 (complement-to-data during write, true data after completion) and toggle-bit monitoring on I/O6. The device includes 64 bytes of dedicated identification memory accessible at 7FC0H–7FFFH using A9 = 12 V, and optional software-controlled data protection enabled via a 3-byte command sequence.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory size | 256 Kbit (32,768 × 8) - provides sufficient nonvolatile storage for boot code, device IDs, and runtime-configurable parameters in resource-constrained controllers. |
| Read access time | 70 ns - enables direct replacement of SRAM in legacy 8-bit microcontroller buses without wait-state insertion. |
| Page write cycle time | ≤10 ms - reduces firmware update latency compared to byte-by-byte writes; supports up to 64-byte burst programming within one internal timer period. |
| Endurance | 100,000 write/erase cycles - validated for applications requiring frequent field-updatable calibration or logging (e.g., industrial sensors, medical diagnostics). |
| Data retention | 10 years at +85°C - ensures long-term reliability in unattended equipment such as remote telemetry nodes and automotive ECUs. |
| Supply voltage | 5 V ±10% - compatible with legacy 5 V TTL/CMOS logic families and eliminates need for level-shifting circuitry. |
| Operating temperature | –40°C to +85°C - certified for industrial-grade deployment in factory automation, power metering, and transportation control units. |
Pinout & Package
AT28HC256E-70JU is packaged in a 32-lead Plastic Leaded Chip Carrier (PLCC) with JEDEC-standard byte-wide pinout. Pins 1 and 17 are "Don't Connect" (DC); pins 12 and 26 are No Connect (NC). All I/O lines (I/O0–I/O7) support bidirectional data transfer with TTL/CMOS-compatible voltage thresholds.
| 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 | Byte-wide parallel interface; I/O7 used for DATA Polling, I/O6 for Toggle Bit detection during write cycles. |
| CE | Chip Enable | Active-low global enable; must be low for read/write access; high state forces outputs to high-impedance and inhibits writes. |
| OE | Output Enable | Active-low read control; used with CE to manage bus contention; high state disables output drivers regardless of CE/WE state. |
| WE | Write Enable | Active-low write strobe; falling edge latches address/data; combined with CE controls byte vs. page write initiation. |
| VCC / GND | Power supply | Single 5 V supply with ≤3 mA standby current; ground reference for all digital and analog functions including VCC-sense protection. |
Key Features
| Feature | Design Value |
|---|---|
| Hardware write protection | VCC sense (inhibits write if VCC < 3.8 V), 5 ms power-on delay, and noise filtering (<15 ns pulse rejection) prevent spurious writes during brown-out or EMI events. |
| Software data protection (SDP) | User-enabled via 3-byte command sequence (AAh/55h/A0h to 5555h/2AAAh/5555h); once activated, all writes require reissuing the sequence - ideal for preventing accidental firmware corruption. |
| Page write capability | Internal 64-byte latch allows sequential loading of up to 64 bytes within 150 µs per byte; eliminates host CPU overhead of individual address setup per byte. |
| Write completion signaling | Dual-mode detection: DATA Polling (I/O7 complement → true data) and Toggle Bit (I/O6 toggling → stable) give designers flexibility in interrupt-driven or polling-based firmware designs. |
| Device identification memory | 64-byte reserved area (7FC0H–7FFFH) accessible with A9 = 12 V; enables unique serialization, manufacturing traceability, or field-programmable feature keys without consuming main array space. |
Applications
| Industrial PLC Configuration Storage | Medical Device Calibration Data Retention |
|---|---|
|
Use Scenario: Storing I/O mapping tables, PID tuning parameters, and safety thresholds in programmable logic controllers deployed in factory environments. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed during boot and runtime; 70 ns read speed ensures deterministic scan-cycle timing in real-time control loops. Use Value: Eliminates need for battery-backed SRAM; 100,000-cycle endurance supports decades of parameter updates across maintenance cycles without wear-out concerns. |
Use Scenario: Preserving sensor calibration coefficients, user preferences, and regulatory audit logs in portable diagnostic instruments operating under strict FDA data integrity requirements. IC Role / Device Role / Timing Role: Secure, tamper-resistant data vault; software data protection prevents unauthorized modification of calibration values during servicing. Use Value: 10-year data retention at +85°C guarantees validity of stored calibration data throughout product lifecycle, even in high-temperature sterilization or storage conditions. |
| Automotive Body Control Module (BCM) Settings | Legacy Industrial Instrumentation Firmware Backup |
|
Use Scenario: Holding seat/mirror position presets, lighting profiles, and CAN node configuration in automotive BCMs where EEPROM must survive repeated ignition cycles and thermal cycling. IC Role / Device Role / Timing Role: Power-fail-safe configuration store; VCC-sense hardware protection blocks writes during cranking-induced voltage dips below 3.8 V. Use Value: Industrial temperature rating (–40°C to +85°C) and green RoHS-compliant PLCC package meet automotive qualification standards for under-hood and cabin-mounted modules. |
Use Scenario: Serving as drop-in replacement for obsolete 27C256 EPROMs in aging test equipment, process controllers, and lab instruments where UV-erasable parts are no longer serviceable. IC Role / Device Role / Timing Role: Pin-compatible parallel memory with identical 28-pin SOIC footprint (via adapter) or native 32-pin PLCC layout; supports same address/data bus timing. Use Value: Eliminates need for PCB redesign - retains existing 5 V bus interface, requires only minor firmware update to leverage page-write acceleration and software protection. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28HC256-70PU | Same die, 28-lead SOIC package (vs. PLCC-32); no DC/NC pins; slightly lower profile and different thermal mass. | Preferred for space-constrained PCBs where surface-mount density matters; lacks PLCC's socket compatibility and mechanical robustness for field-replaceable modules. | Select AT28HC256-70PU when board real estate is limited and reworkability is less critical than component height. |
| ST M28W256FCT | 256 Kbit parallel EEPROM with 120 ns access time; 3.3 V/5 V dual-supply capable; supports faster 3 ms page write (F-version variant). | Designed for mixed-voltage systems; not pin-compatible - requires layout change due to different pinout and VPP requirement for write operations. | Choose ST M28W256FCT only when migrating to 3.3 V domains or requiring extended voltage flexibility; not a drop-in replacement. |
Compared with AT28HC256-70PU, the AT28HC256E-70JU offers superior mechanical stability and socket-based field upgrades via its PLCC package, while ST M28W256FCT introduces voltage flexibility at the cost of pin compatibility and requires redesign for VPP routing and timing adaptation.
Availability
AT28HC256E-70JU is available at Aetrix Electronics and suitable for industrial control, medical instrumentation, automotive body electronics, and legacy system modernization requiring stable component supply and long-term obsolescence management.
Supply support for AT28HC256E-70JU 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 leading provider of microcontrollers, analog devices, and memory solutions, with a focus on embedded control and connectivity applications across industrial, automotive, and consumer markets.
The AT28HC256 belongs to Microchip's legacy parallel EEPROM product line, engineered for reliable, low-power nonvolatile storage in systems where simplicity, 5 V compatibility, and long data retention outweigh serial interface advantages.
FAQ
What is the maximum page write size supported by the AT28HC256E-70JU?
The AT28HC256E-70JU supports up to 64 bytes per page write operation. This is enabled by an internal 64-byte page register that latches address and data simultaneously. Each byte in the page must be loaded within 150 µs of the prior byte (tBLC), and all addresses must reside on the same page defined by A6–A14. The AT28HC256E-70JU completes the internal programming automatically after the final byte is latched.
Does the AT28HC256E-70JU require a high-voltage VPP pin for programming?
No, the AT28HC256E-70JU operates with a single 5 V ±10% supply and does not require a separate VPP pin. Programming is performed using standard 5 V logic levels on WE, CE, and OE. High-voltage (12 V) is only required for accessing the 64-byte device identification memory at addresses 7FC0H–7FFFH - not for normal read/write operations. The AT28HC256E-70JU integrates VCC sensing to inhibit writes below 3.8 V, eliminating external voltage boosters.
How does software data protection work on the AT28HC256E-70JU?
Software data protection (SDP) on the AT28HC256E-70JU is enabled by writing three specific bytes (AAh, 55h, A0h) to addresses 5555h, 2AAAh, and 5555h respectively. Once activated, all subsequent writes require repeating this sequence before data. The AT28HC256E-70JU ships with SDP disabled. Disabling SDP uses a different 6-byte sequence (AAh/55h/80h/AAh/55h/20h). SDP remains active across power cycles and protects against accidental writes during power-up/down transitions.
Can the AT28HC256E-70JU be used as a direct replacement for the AT28HC256-70PU?
No - the AT28HC256E-70JU (PLCC-32) and AT28HC256-70PU (SOIC-28) are not pin-compatible. While functionally identical, they differ in package type, pin count, pinout, and mechanical dimensions. The AT28HC256E-70JU has DC and NC pins (1, 12, 17, 26) absent in the SOIC version, and its address/data mapping differs due to package geometry. Direct substitution requires PCB redesign or use of a PLCC-to-SOIC adapter. The AT28HC256E-70JU is optimized for socketed, serviceable installations.
What is the purpose of the 64-byte identification memory in the AT28HC256E-70JU?
The 64-byte identification memory (addresses 7FC0H–7FFFH) in the AT28HC256E-70JU is reserved for device-specific data such as serial numbers, manufacturing lot codes, calibration timestamps, or feature unlock keys. Access requires raising A9 to 12 V ±0.5 V - a separate voltage condition from normal operation. This area is electrically isolated from the main array, enabling secure, infrequently updated metadata storage without impacting main memory endurance or requiring special erase procedures. The AT28HC256E-70JU treats it as a dedicated, protected region.
AT28HC256E-70JU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 32-LCC (J-Lead)
- Packaging:
- Tube
- Product Status:
- Active
- Programmable:
- 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:
- 32-PLCC (13.97x11.43)
AT28HC256E-70JU FAQ
1.How can I place an order for AT28HC256E-70JU through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28HC256E-70JU 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-70JU reliable?
The price and inventory of AT28HC256E-70JU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28HC256E-70JU is usually 5 days.
3.What payment methods are accepted for AT28HC256E-70JU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28HC256E-70JU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28HC256E-70JU?
AT28HC256E-70JU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28HC256E-70JU 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-70JU?
For technical support, including AT28HC256E-70JU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28HC256E-70JU requirements.
6.How does Aetrix verify that AT28HC256E-70JU is sourced from the original manufacturer or authorized distributors?
All AT28HC256E-70JU 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-70JU meets industry standards.
7.What is the process for return or replacement of AT28HC256E-70JU?
All AT28HC256E-70JU units undergo pre-shipment inspection (PSI). If there is an issue with AT28HC256E-70JU, 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-70JU part is unused and in its original packaging.
Return procedure for AT28HC256E-70JU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT28HC256E-70JU Tags
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