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Microchip Technology AT28HC256-12JC
- Part No.:
- AT28HC256-12JC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT28HC256-12JC.pdf
- Description:
- IC EEPROM 256KBIT PAR 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:2,002
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Product details
Overview
AT28HC256-12JC from Atmel is a 256 Kbit (32K × 8) parallel EEPROM IC designed for nonvolatile data storage in embedded control and instrumentation systems. It delivers 120 ns read access time, supports 1–64-byte page writes with internal latching and timer control, operates on single 5V ±10% supply, and is rated for industrial temperature range (−40°C to +85°C) in 28-pin SOIC package.
For engineers reviewing the AT28HC256-12JC datasheet, AT28HC256-12JC pinout, AT28HC256-12JC application, or AT28HC256-12JC equivalent, this page provides verified electrical specifications, JEDEC-compliant byte-wide interface details, hardware/software write protection mechanisms, DATA polling and toggle-bit write completion detection, and validated industrial-grade packaging information.
Technical Context
The AT28HC256-12JC implements a CMOS-based parallel EEPROM architecture with internal address/data latches for up to 64-byte page writes and an autonomous internal control timer that eliminates external timing circuitry. Its dual-line chip enable (CE) and output enable (OE) logic enables flexible bus contention management in shared-memory systems.
Write operations support both byte and page modes, with page writes constrained to same-page addressing (A6–A14 fixed), while DATA polling on I/O7 and toggle-bit monitoring on I/O6 provide deterministic end-of-write detection without requiring precise timing margins.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8), organized as byte-addressable nonvolatile storage |
| Read Access Time | 120 ns maximum - defines minimum clock-to-data latency in SRAM-compatible read cycles |
| Page Write Cycle Time | 10 ms maximum - determines worst-case duration before next memory access can begin |
| VCC Supply | 5 V ±10% - compatible with standard TTL/CMOS logic rails without regulation overhead |
| Operating Temperature | −40°C to +85°C - qualified for industrial environments including factory automation and motor control |
| Endurance | 10,000 write/erase cycles - specifies guaranteed reprogrammability before parametric degradation |
| Data Retention | 10 years at 85°C - ensures long-term validity of stored configuration or calibration data |
| Standby Current | 3 mA maximum - enables low-power sleep states in battery-backed or energy-constrained systems |
Pinout & Package
AT28HC256-12JC is supplied in a 28-lead, 0.300" wide plastic gull-wing small outline integrated circuit (SOIC) package per JEDEC MS-013, with 1.27 mm lead pitch and surface-mount compatibility.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus selecting one of 32,768 bytes; A6–A14 define page boundaries for page writes |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel interface supporting read, byte write, and page write; high-impedance during standby |
| CE | Chip Enable | Active-low global device select; must be low with OE low and WE high for valid read operation |
| OE | Output Enable | Active-low output gate control; used with CE to prevent bus contention during multi-device sharing |
| WE | Write Enable | Active-low signal initiating byte or page write; falling edge latches address and data |
| VCC | Power Supply | +5 V ±10% main supply; powers core logic and memory array |
| GND | Ground Reference | Signal and power return path; decoupling required near VCC pin |
| NC | No Connect | Pins 1 and 17 in PLCC variant only - not present in SOIC (AT28HC256-12JC); ignored in this package |
Key Features
| Feature | Design Value |
|---|---|
| JEDEC Byte-wide Pinout | Ensures drop-in compatibility with legacy SRAM and EPROM sockets in existing PCB layouts |
| Hardware Write Inhibit | VCC sense (<3.8 V), 5 ms power-on delay, and noise filtering (<15 ns pulses) prevent spurious writes during power transitions |
| Software Data Protection (SDP) | User-configurable 3-byte unlock sequence prevents accidental writes without compromising full memory accessibility |
| DATA Polling & Toggle Bit | Dual asynchronous write completion detection methods eliminate need for fixed delay timers in host firmware |
| 64-byte Page Register | Enables burst programming of contiguous data without repeated address setup, reducing system bus occupancy |
| Extra 64-byte ID EEPROM | Dedicated user-accessible memory region (7FC0H–7FFFH) for device serialization or calibration storage |
Applications
| Industrial PLC Configuration Storage | Medical Device Calibration Data |
|---|---|
Use Scenario: Storing I/O mapping, ladder logic parameters, and alarm thresholds in programmable logic controllers deployed in factory environments. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed via parallel bus during boot and runtime parameter updates. Use Value: 10,000-cycle endurance and −40°C to +85°C operation ensure reliable retention across decades of industrial use cycles. | Use Scenario: Holding sensor calibration coefficients, patient-specific settings, and firmware revision metadata in portable diagnostic equipment. IC Role / Device Role / Timing Role: Secure, low-power EEPROM providing tamper-resistant storage for safety-critical operational data. Use Value: Hardware VCC-sense and software data protection prevent corruption during brown-out or ESD events common in clinical settings. |
| Automotive Body Control Module | Test & Measurement Equipment Setup |
Use Scenario: Saving seat/mirror position presets, lighting profiles, and door lock configurations in automotive BCMs. IC Role / Device Role / Timing Role: Parallel EEPROM interfaced directly to microcontroller GPIO or memory-mapped bus for fast read/write access. Use Value: 120 ns read speed enables real-time recall of user preferences without interrupting vehicle subsystem responsiveness. | Use Scenario: Storing instrument-specific test sequences, probe compensation values, and user-defined measurement limits in benchtop analyzers. IC Role / Device Role / Timing Role: Standalone nonvolatile memory holding persistent setup state between power cycles and firmware updates. Use Value: 10-year data retention guarantees accuracy of stored calibration data across extended service intervals and field deployments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28C256-12JC | Same pinout and timing but lower endurance (100 write cycles vs. 10,000); no software data protection | Suitable only for infrequent configuration updates where long-term reliability is secondary | Select only if cost sensitivity outweighs field longevity and security requirements |
| MN5Q2568B-12PL | 120 ns access, 28-pin PLCC, 5V-only operation, but lacks page write and DATA polling features | Requires external timing control and polling logic; higher firmware overhead for write completion handling | Prefer when legacy PLCC footprint is mandatory and simplified write protocol suffices |
Compared with AT28HC256-12JC, AT28C256-12JC offers identical interface timing but sacrifices endurance and data integrity safeguards, while MN5Q2568B-12PL retains speed and voltage compatibility but removes autonomous page write and end-of-write detection-increasing host MCU resource burden.
Availability
AT28HC256-12JC is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, automotive body electronics, and test equipment requiring stable component supply with guaranteed long-term availability and traceable sourcing.
Supply support for AT28HC256-12JC 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
Atmel Corporation (now part of Microchip Technology) is a semiconductor manufacturer specializing in microcontrollers, nonvolatile memory, and secure authentication devices.
The AT28HC256 product line was engineered for robust, pin-compatible replacement of UV-erasable EPROMs and early flash memory in industrial control, instrumentation, and telecom infrastructure where predictable timing, high write endurance, and hardware-level data protection are critical.
FAQ
What is the maximum page write size supported by the AT28HC256-12JC?
The AT28HC256-12JC supports up to 64 bytes per page write operation. This is enabled by its internal 64-byte page register, which latches address and data on the first write pulse and allows up to 63 additional bytes to be loaded within 150 µs of each prior byte. All bytes in a given page write must reside on the same page, defined by fixed A6–A14 address bits.
Does the AT28HC256-12JC require external high-voltage programming circuitry?
No, the AT28HC256-12JC operates entirely from a single 5V ±10% supply and does not require external high-voltage programming circuitry. Unlike older EPROMs, it uses internal charge pumps for write/erase operations. The only exception is optional device identification memory (7FC0H–7FFFH), which requires 12V on A9-but this is not used during normal operation of the AT28HC256-12JC.
How does hardware write protection function on the AT28HC256-12JC?
Hardware write protection on the AT28HC256-12JC includes four mechanisms: (1) VCC sense inhibits writes below ~3.8 V; (2) automatic 5 ms power-on delay after VCC stabilization; (3) write inhibition when CE is high, OE is low, or WE is high; and (4) noise filtering rejecting input pulses under 15 ns. These operate independently of software data protection and are always active in the AT28HC256-12JC.
Can the AT28HC256-12JC be used as a direct replacement for standard SRAM in existing designs?
Yes, the AT28HC256-12JC is accessed like a static RAM for reads and writes without external components, supporting identical CE/OE/WE control timing. However, write cycles take up to 10 ms and require polling or toggle-bit verification-so timing-critical SRAM paths must be modified to accommodate non-instantaneous writes. Read operations remain fully SRAM-compatible with 120 ns access.
What package type is used for the AT28HC256-12JC, and is it RoHS-compliant?
The AT28HC256-12JC uses a 28-lead, 0.300" wide plastic gull-wing small outline (SOIC) package (ordering code suffix "JC"). Per Atmel documentation, it is offered in a green (Pb/halide-free) packaging option and complies with RoHS Directive 2011/65/EU. The "JC" suffix specifically denotes this SOIC industrial-temperature variant.
AT28HC256-12JC Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 32-LCC (J-Lead)
- Packaging:
- Tube
- 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:
- 0°C ~ 70°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-PLCC (13.97x11.43)
AT28HC256-12JC FAQ
1.How can I place an order for AT28HC256-12JC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28HC256-12JC 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 AT28HC256-12JC reliable?
The price and inventory of AT28HC256-12JC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28HC256-12JC is usually 5 days.
3.What payment methods are accepted for AT28HC256-12JC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28HC256-12JC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28HC256-12JC?
AT28HC256-12JC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28HC256-12JC 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 AT28HC256-12JC?
For technical support, including AT28HC256-12JC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28HC256-12JC requirements.
6.How does Aetrix verify that AT28HC256-12JC is sourced from the original manufacturer or authorized distributors?
All AT28HC256-12JC 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 AT28HC256-12JC meets industry standards.
7.What is the process for return or replacement of AT28HC256-12JC?
All AT28HC256-12JC units undergo pre-shipment inspection (PSI). If there is an issue with AT28HC256-12JC, 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 AT28HC256-12JC part is unused and in its original packaging.
Return procedure for AT28HC256-12JC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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