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Microchip Technology AT28HC256F-12SC
- Part No.:
- AT28HC256F-12SC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
AT28HC256F-12SC.pdf
- Description:
- IC EEPROM 256KBIT PAR 28SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,424
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Product details
Overview
AT28HC256F-12SC from Microchip Technology (formerly Atmel) is a 256 Kbit (32K × 8) parallel EEPROM with JEDEC-standard byte-wide pinout, 120 ns access time, 3 ms fast page write cycle, and industrial temperature range (–40°C to +85°C) in 28-pin SOIC package. It operates from a single 5V ±10% supply and supports hardware/software data protection for embedded control and firmware storage applications.
For engineers reviewing the AT28HC256F-12SC datasheet, AT28HC256F-12SC pinout, AT28HC256F-12SC application, or AT28HC256F-12SC equivalent, key selection criteria include verified 3 ms page write performance, CMOS/TTL compatibility, DATA polling and toggle-bit write completion detection, and industrial-grade reliability with 10⁴ write cycles and 10-year data retention.
Technical Context
The AT28HC256F-12SC implements a parallel interface with full static RAM-like read/write operation-no external timing components required. Its internal 64-byte page register enables burst writes without bus hold, while automatic internal control timer manages write execution after address/data latching.
Write completion is confirmed via dual methods: DATA polling on I/O7 (complement-to-data during write, true data upon completion) and toggle-bit behavior on I/O6. Hardware protection includes VCC sense (<3.8 V inhibits write), 5 ms power-on delay, and noise filtering on WE/CE inputs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8 bits) - supports firmware image storage or configuration tables in microcontroller-based systems |
| Access Time | 120 ns - compatible with 8 MHz Z80, 68K, and legacy 8/16-bit bus timing budgets |
| Page Write Time | 3 ms maximum - reduces system latency vs. standard 10 ms variant, critical for real-time parameter updates |
| Endurance | 10,000 write/erase cycles - sufficient for field-updatable calibration data or logging in industrial controllers |
| Data Retention | 10 years at +85°C - validated for long-life deployments in unattended equipment |
| Supply Voltage | 5 V ±10% - interoperable with legacy 5 V logic families without level-shifting |
| Operating Temp | –40°C to +85°C - qualified for industrial automation, motor drives, and outdoor metering |
Pinout & Package
AT28HC256F-12SC is housed in a 28-lead, 0.300" wide plastic gull-wing small outline (SOIC) package (package code "S"), compliant with JEDEC MS-013 and RoHS/Green (Pb/halide-free) requirements.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus selects one of 32,768 bytes; A6–A14 define page boundaries for 64-byte page writes |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel interface; supports true read/write without direction control pins |
| CE | Chip Enable | Active-low chip select; must be low with OE low and WE high for read access |
| OE | Output Enable | Active-low output gate; controls data bus tristate to prevent contention during shared-bus operation |
| WE | Write Enable | Active-low write strobe; falling edge latches address/data; initiates byte or page write sequence |
| VCC | Power Supply | +5 V ±10% supply; internal VCC sense disables writes below ~3.8 V for power-fail safety |
| GND | Ground Reference | Signal and power return; decoupling capacitor placement near this pin minimizes noise during write operations |
Key Features
| Feature | Design Value |
|---|---|
| Fast Page Write (3 ms) | Reduces firmware update time by 70% vs. 10 ms variants-enables faster field reprogramming in PLCs and HMI modules |
| DATA Polling & Toggle Bit | Dual, software-transparent write completion detection eliminates need for fixed delays or external timers in host firmware |
| Hardware + Software Data Protection | VCC sensing, noise filtering, and 3-byte SDP command sequence prevent accidental writes during power transitions or ESD events |
| JEDEC Byte-Wide Pinout | Drop-in replacement for industry-standard 27C256, 27C512, and other parallel EPROM/EEPROM sockets without PCB redesign |
| Industrial Temperature Range | Validated operation from –40°C to +85°C ensures reliability in motor control cabinets, solar inverters, and railway signaling systems |
Applications
| Industrial Firmware Storage | Embedded Configuration Memory |
|---|---|
Use Scenario: Storing bootloader code and factory calibration constants in programmable logic controllers (PLCs) operating in factory-floor environments with wide ambient temperature swings. IC Role / Device Role / Timing Role: Nonvolatile program memory accessed via parallel bus during MCU reset and initialization sequences; 120 ns access supports tight boot-time constraints. Use Value: Enables field-upgradable firmware without requiring external programming hardware; 10-year retention ensures calibration integrity across maintenance cycles. | Use Scenario: Holding user-defined parameters (e.g., PID coefficients, alarm thresholds) in HVAC controllers where settings must survive AC power loss. IC Role / Device Role / Timing Role: Configuration EEPROM interfaced directly to 8-bit microcontroller GPIO or dedicated memory bus; software-controlled page writes minimize update latency. Use Value: 3 ms page write allows rapid parameter save during runtime; hardware write inhibit prevents corruption during brownout conditions. |
| Legacy System Replacement | Secure Device Identification |
Use Scenario: Replacing obsolete 27C256 EPROMs in avionics test equipment where UV-erasable parts are no longer supportable. IC Role / Device Role / Timing Role: Pin-compatible parallel memory drop-in; JEDEC-compliant pinout and 5 V TTL/CMOS I/O eliminate adapter boards or layout changes. Use Value: Eliminates UV eraser dependency and enables in-system reprogramming; 10⁴ endurance supports repeated test script updates over equipment lifetime. | Use Scenario: Storing unique serial numbers and manufacturing traceability data in medical diagnostic devices requiring regulatory audit trails. IC Role / Device Role / Timing Role: Dedicated 64-byte identification EEPROM region (7FC0H–7FFFH) accessible via 12 V on A9; isolated from main array to prevent accidental overwrite. Use Value: Provides tamper-resistant device fingerprinting without consuming main memory space; supports ISO 13485 compliance for production lot tracking. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28HC256F-12SI | Same 3 ms page write and 120 ns access, but in 28-pin PDIP (package code "P") instead of SOIC | Preferred for through-hole prototyping or legacy board repair where SOIC footprint is unavailable | Select when mechanical mounting or hand-soldering is required; identical electrical behavior and timing |
| AT28HC256-12SC | Same SOIC package and industrial temp range, but standard 10 ms page write (no "F" fast-write option) | Suitable for non-time-critical configuration storage where write latency is not constrained | Choose for cost-sensitive designs where 3 ms speed is unnecessary; lower unit cost than F-version |
Compared with AT28HC256F-12SI and AT28HC256-12SC, the AT28HC256F-12SC uniquely delivers fast 3 ms page writes in a surface-mount SOIC package qualified for industrial temperatures-making it optimal for space-constrained, high-reliability embedded systems requiring rapid field updates.
Availability
AT28HC256F-12SC is available at Aetrix Electronics and suitable for industrial automation, embedded control, and legacy system modernization requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for AT28HC256F-12SC 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 acquired Atmel in 2016 and maintains full support for the AT28HC256 family, including datasheets, application notes, and long-term product availability commitments.
The AT28HC256 series was designed as a direct, pin-compatible EEPROM replacement for UV-erasable EPROMs in 8/16-bit embedded systems-emphasizing ease of migration, robust write protection, and industrial-grade reliability without external circuitry.
FAQ
What is the guaranteed page write time for AT28HC256F-12SC?
The AT28HC256F-12SC guarantees a maximum page write time of 3 ms, as specified in the "Page Mode Write Characteristics" table (Section 16). This is enabled by the "F" option in the part number and distinguishes it from the standard 10 ms version. The 3 ms performance is validated across the full industrial temperature range (–40°C to +85°C) and applies to all 1–64 byte writes within a single page boundary defined by A6–A14.
Does AT28HC256F-12SC require a 12 V supply for any operation?
No, AT28HC256F-12SC operates exclusively from a single 5 V ±10% supply under normal read/write conditions. The 12 V requirement applies only to the optional device identification memory region (7FC0H–7FFFH), which is separate from main array operation. Standard firmware storage, configuration, and page writes use only 5 V; no 12 V circuitry is needed unless utilizing the dedicated ID EEPROM section.
How does software data protection (SDP) work on AT28HC256F-12SC?
AT28HC256F-12SC implements SDP via a three-byte unlock sequence written to specific addresses (5555H, 2AAAH, then 5555H with A0 data). Once enabled, all subsequent writes require repeating this sequence before data. SDP remains active across power cycles and protects against accidental writes during brownouts. The AT28HC256F-12SC ships with SDP disabled; users enable it only if required for their system's security model.
Can AT28HC256F-12SC be used as a direct replacement for AT27C256B EPROMs?
Yes, AT28HC256F-12SC is a functional and pin-compatible replacement for AT27C256B EPROMs in most designs. It shares identical JEDEC byte-wide pinout, 5 V operation, and 28-pin SOIC package. Unlike EPROMs, it requires no UV erasure and supports in-system reprogramming-but note that CE/OE/WE timing and write-enable behavior differ, so existing firmware must implement DATA polling or toggle-bit detection instead of fixed delays.
What is the meaning of "SC" in AT28HC256F-12SC?
In AT28HC256F-12SC, "SC" denotes the package type and temperature grade: "S" = 28-pin SOIC (0.300" wide), and "C" = commercial temperature range (0°C to +70°C). However, per Section 27.1 of the datasheet, the "SC" suffix is also used for industrial-grade parts in SOIC packages-confirmed by ordering code AT28HC256F-12SI (industrial) and AT28HC256F-12SC (commercial). For this specific part, "SC" indicates SOIC package with commercial temperature rating.
AT28HC256F-12SC Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-SOIC (0.295", 7.50mm Width)
- 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:
- 3ms
- 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:
- 28-SOIC
AT28HC256F-12SC FAQ
1.How can I place an order for AT28HC256F-12SC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28HC256F-12SC 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 AT28HC256F-12SC reliable?
The price and inventory of AT28HC256F-12SC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28HC256F-12SC is usually 5 days.
3.What payment methods are accepted for AT28HC256F-12SC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28HC256F-12SC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28HC256F-12SC?
AT28HC256F-12SC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28HC256F-12SC 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 AT28HC256F-12SC?
For technical support, including AT28HC256F-12SC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28HC256F-12SC requirements.
6.How does Aetrix verify that AT28HC256F-12SC is sourced from the original manufacturer or authorized distributors?
All AT28HC256F-12SC 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 AT28HC256F-12SC meets industry standards.
7.What is the process for return or replacement of AT28HC256F-12SC?
All AT28HC256F-12SC units undergo pre-shipment inspection (PSI). If there is an issue with AT28HC256F-12SC, 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 AT28HC256F-12SC part is unused and in its original packaging.
Return procedure for AT28HC256F-12SC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT28HC256F-12SC Tags
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AT24C02C-XHM-T
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