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Microchip Technology AT28C256-15SU
- Part No.:
- AT28C256-15SU
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
AT28C256-15SU.pdf
- Description:
- IC EEPROM 256KBIT PAR 28SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,830
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Product details
Overview
AT28C256-15SU from Microchip Technology is an industrial-grade paged parallel EEPROM with 256-Kbit (32,768 × 8) organization, 150 ns read access time, single 5V ±10% supply, and JEDEC-approved byte-wide pinout. It serves as nonvolatile program/data storage in microcontroller-based systems requiring field-updatable firmware or configuration data.
For engineers reviewing the AT28C256-15SU datasheet, AT28C256-15SU pinout, AT28C256-15SU application, or AT28C256-15SU equivalent, key selection criteria include page write capability (1–64 bytes), DATA Polling/Toggle Bit end-of-write detection, hardware/software data protection, industrial temperature range (–40°C to +85°C), and compatibility with TTL/CMOS bus interfaces.
Technical Context
The AT28C256-15SU implements a paged architecture with a 64-byte internal page register, enabling simultaneous latching of up to 64 bytes before autonomous internal programming. Its dual-line chip enable (CE) and output enable (OE) control supports flexible bus contention management in shared-memory systems.
Write operation relies on internal timing: page write cycle time is 10 ms maximum (AT28C256-15 variant), with byte load cycle limit of 150 µs between successive writes within a page. End-of-write detection is implemented via DATA Polling on I/O7 (complement-to-data during write) and Toggle Bit behavior on I/O6.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory size | 256 Kbit (32,768 × 8) - provides sufficient space for boot code, calibration tables, or device configuration in embedded controllers |
| Read access time | 150 ns - enables direct replacement of SRAM in legacy 8-bit systems without timing redesign |
| Page write cycle time | 10 ms max - defines minimum interval between consecutive page writes; critical for firmware update throughput planning |
| VCC supply | 5V ±10% - ensures interoperability with standard 5V logic families and eliminates need for auxiliary voltage rails |
| Operating temperature | –40°C to +85°C - qualified for industrial environments including factory automation and instrumentation |
| Endurance | 10,000 write/erase cycles - supports moderate-field-update applications such as parameter logging or calibration revision tracking |
| Data retention | 10 years - guarantees long-term integrity of stored configuration or serial number data without refresh |
Pinout & Package
AT28C256-15SU is supplied in 28-lead SOIC package (SOIC-28), with JEDEC-standard byte-wide pinout compatible with industry-common EEPROM footprints.
| 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 page write operations |
| I/O0–I/O7 | Bidirectional data bus | 8-bit parallel interface; I/O7 used for DATA Polling, I/O6 for Toggle Bit status indication during write cycles |
| CE | Chip Enable | Active-low global enable; must be low for read/write access; high-Z output when asserted high |
| OE | Output Enable | Active-low output control; allows CE-driven chip select while gating output drivers independently |
| WE | Write Enable | Active-low write strobe; falling edge latches address and data; initiates byte or page write sequence |
| VCC | Power supply | +5V ±10% main supply; powers core logic and memory array; includes VCC sense circuitry for write inhibit below 3.8V |
| GND | Ground reference | Signal and power return path; required for stable DC bias and noise margin compliance |
Key Features
| Feature | Design Value |
|---|---|
| 64-byte page register | Enables burst loading of up to 64 bytes before internal programming begins, reducing host CPU overhead during firmware updates |
| DATA Polling (I/O7) | Allows real-time polling of write completion without external wait-state generators or fixed delays |
| Toggle Bit (I/O6) | Provides alternative asynchronous write-status feedback independent of data content, simplifying interrupt-driven write handling |
| Hardware write protection | VCC sense, 5 ms power-on delay, and noise filtering (<15 ns) prevent spurious writes during power ramp or EMI events |
| Software Data Protection (SDP) | Three-byte unlock sequence (AAh/55h/A0h) enables selective write-enable per sector, preventing accidental overwrites in multi-tasking environments |
Applications
| Industrial PLC Configuration Storage | Legacy Embedded System Firmware Backup |
|---|---|
Use Scenario: Storing I/O mapping, PID tuning parameters, and alarm thresholds in programmable logic controllers operating in factory-floor environments. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed during boot and runtime via parallel bus; requires guaranteed data retention across 10-year maintenance cycles. Use Value: Eliminates need for battery-backed SRAM while maintaining compatibility with existing 5V microcontroller address/data buses and timing constraints. |
Use Scenario: Providing fallback firmware image for 8051- or Z80-based medical instruments where field upgrades are infrequent but mission-critical. IC Role / Device Role / Timing Role: Secondary boot memory mapped alongside primary ROM; read-access latency ≤150 ns ensures no performance penalty during cold start. Use Value: Enables safe firmware recovery after failed update by storing validated image copy, leveraging built-in DATA Polling to verify write integrity pre-reboot. |
| Point-of-Sale Terminal Serial Number Registry | Automated Test Equipment Calibration Data |
Use Scenario: Recording unique device identifiers and manufacturing trace codes during final test of retail payment terminals. IC Role / Device Role / Timing Role: One-time or infrequent write storage location; uses software data protection to prevent overwrite after commissioning. Use Value: Guarantees tamper-resistant serialization using SDP lock mechanism, with 10,000-cycle endurance exceeding lifetime device requirements. |
Use Scenario: Holding sensor offset/gain coefficients and fixture compensation values in benchtop multimeters and signal analyzers. IC Role / Device Role / Timing Role: Calibration memory accessed at power-on and during self-test; requires stable data retention over 10+ years without refresh. Use Value: Replaces costly battery-backed RAM with zero-maintenance nonvolatile storage, validated for industrial temperature cycling and long-term shelf life. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar paged parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28C256-15PU | Same electrical specs and pinout; packaged in 28-lead PDIP instead of SOIC | Suitable for through-hole prototyping or legacy board rework where SOIC footprint unavailable | Select when manual soldering, socket-based development, or mechanical robustness in vibration-prone environments is prioritized |
| M95256-DW | Serial SPI interface (not parallel); 256 Kbit density; 5V-tolerant I/O; 5 ms typical write time | Requires SPI controller interface and software driver changes; lacks byte/page write flexibility of parallel bus | Choose for space-constrained designs where PCB real estate favors serial interface and system already uses SPI peripherals |
Compared with AT28C256-15PU, the AT28C256-15SU offers surface-mount reliability and thermal performance advantages; compared with M95256-DW, it delivers deterministic parallel-bus timing and direct microcontroller bus integration without protocol translation overhead.
Availability
AT28C256-15SU is available at Aetrix Electronics and suitable for industrial PLC configuration storage, legacy embedded system firmware backup, point-of-sale terminal serial number registry, and automated test equipment calibration data requiring stable component supply across extended production lifecycles.
Supply support for AT28C256-15SU 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 a focus on industrial, automotive, and aerospace applications.
The AT28C256 belongs to Microchip's legacy parallel EEPROM product line, designed specifically for drop-in replacement of EPROM and battery-backed SRAM in mature 5V embedded systems requiring field-updatable nonvolatile storage.
FAQ
What is the maximum page write size supported by the AT28C256-15SU?
The AT28C256-15SU supports up to 64 bytes per page write operation. This is enabled by its internal 64-byte page register, which latches address and data before initiating autonomous internal programming. Each byte within a page must be loaded within 150 µs of the prior byte; exceeding this interval triggers immediate write execution. The AT28C256-15SU does not support larger page sizes or partial-page writes outside this constraint.
Does the AT28C256-15SU require external high-voltage programming circuitry?
No, the AT28C256-15SU operates from a single 5V ±10% supply and performs all write/erase functions internally without external high-voltage generation. Chip erase requires only a 12V pulse on A9 - but this is optional and not needed for standard byte or page writes. All normal programming is executed using standard 5V logic levels on CE, WE, OE, and I/O lines, making the AT28C256-15SU compatible with conventional 5V microcontroller buses.
How does DATA Polling work on the AT28C256-15SU during a write cycle?
During a write cycle, reading the last written address returns the complement of the written data on I/O7. Once the internal programming completes, true data appears on I/O7 and all other I/O lines. This allows the host system to poll I/O7 in a loop without inserting fixed delays - the transition from complement to true data signals write completion. The AT28C256-15SU guarantees this behavior across its full industrial temperature range and supply voltage tolerance.
Is the AT28C256-15SU pin-compatible with older Atmel AT28C256 variants?
Yes, the AT28C256-15SU maintains identical pinout, electrical characteristics, and timing specifications as earlier Atmel-branded AT28C256 versions, including the AT28C256-15PU and AT28C256-15JI. It adheres strictly to the JEDEC-approved byte-wide 28-pin layout and supports the same AC/DC operating ranges, ensuring seamless substitution in existing designs without PCB or firmware modification.
What is the purpose of the extra 64 bytes of EEPROM in the AT28C256-15SU?
The AT28C256-15SU includes 64 bytes of dedicated identification memory (addresses 7FC0H–7FFFH) accessible by raising A9 to 12V ±0.5V. This area is intended for permanent device-specific data such as serial numbers, calibration constants, or manufacturing trace codes. Unlike main array writes, these bytes are programmed separately and remain protected from standard write cycles, enhancing security and traceability in production and field service workflows.
AT28C256-15SU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-SOIC (0.295", 7.50mm Width)
- 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:
- 150 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-SOIC
AT28C256-15SU FAQ
1.How can I place an order for AT28C256-15SU through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28C256-15SU 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 AT28C256-15SU reliable?
The price and inventory of AT28C256-15SU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28C256-15SU is usually 5 days.
3.What payment methods are accepted for AT28C256-15SU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28C256-15SU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28C256-15SU?
AT28C256-15SU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28C256-15SU 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 AT28C256-15SU?
For technical support, including AT28C256-15SU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28C256-15SU requirements.
6.How does Aetrix verify that AT28C256-15SU is sourced from the original manufacturer or authorized distributors?
All AT28C256-15SU 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 AT28C256-15SU meets industry standards.
7.What is the process for return or replacement of AT28C256-15SU?
All AT28C256-15SU units undergo pre-shipment inspection (PSI). If there is an issue with AT28C256-15SU, 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 AT28C256-15SU part is unused and in its original packaging.
Return procedure for AT28C256-15SU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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