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Microchip Technology AT28HC256F-12SI
- Part No.:
- AT28HC256F-12SI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
AT28HC256F-12SI.pdf
- Description:
- IC EEPROM 256KBIT PAR 28SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,129
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Product details
Overview
AT28HC256F-12SI from Microchip Technology (formerly Atmel) is a 256 Kbit parallel EEPROM organized as 32,768 × 8 bits, featuring 70 ns read access time, 3 ms page write cycle, and industrial temperature operation (–40°C to +85°C) in SOIC-28 package. It supports hardware/software data protection, DATA polling, and toggle-bit write completion detection for embedded firmware storage and configuration retention.
For engineers reviewing the AT28HC256F-12SI datasheet, AT28HC256F-12SI pinout, AT28HC256F-12SI application, or AT28HC256F-12SI equivalent, key selection criteria include fast 3 ms page write capability, JEDEC-standard byte-wide parallel interface, industrial-grade reliability (10⁴ write cycles, 10-year data retention), and compatibility with 5V ±10% supply and TTL/CMOS logic levels.
Technical Context
The AT28HC256F-12SI implements a CMOS-based parallel EEPROM architecture with internal 64-byte page latching and autonomous control timer for self-timed writes. Its dual-line chip enable (CE) and output enable (OE) logic enables bus contention avoidance in microcontroller systems.
Write operations support both byte and page modes: page writes accept up to 64 bytes within 150 µs inter-byte timing (tBLC), while software data protection uses a three-byte command sequence (AAh→55h→A0h) to lock/unlock memory. Device identification EEPROM (64 bytes) is accessible via A9 = 12 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8) - sufficient for boot code, calibration tables, or device configuration in resource-constrained systems |
| Read Access Time | 120 ns - meets timing requirements for 8-bit microcontrollers running at ≤8 MHz with no wait states |
| Page Write Cycle Time | 3 ms maximum - reduces firmware update latency by 67% vs. standard 10 ms variant (AT28HC256-12) |
| Endurance | 10,000 write/erase cycles - supports field-upgradable systems requiring infrequent but robust nonvolatile storage |
| Data Retention | 10 years at +85°C - ensures long-term integrity of stored parameters in industrial environments |
| Supply Voltage | 5 V ±10% - interoperable with legacy 5V logic families without level-shifting circuitry |
| Operating Temperature | –40°C to +85°C - qualified for industrial control, automotive body electronics, and outdoor instrumentation |
Pinout & Package
AT28HC256F-12SI is housed in a 28-lead, 0.300" wide plastic gull-wing small outline integrated circuit (SOIC-28) 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 supporting full 32K-word addressing; A6–A14 define page boundaries for 64-byte page writes |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel interface compatible with 8051, Z80, and 68K family microcontrollers; high-impedance during standby |
| CE | Chip Enable | Active-low global select; must be low with OE low and WE high for read access; inhibits writes when high |
| OE | Output Enable | Active-low output control; used with CE to manage bus contention; high during write cycles |
| WE | Write Enable | Active-low write strobe; falling edge latches address/data; toggling I/O6 indicates write progress |
| VCC, GND | Power Supply | Single 5V supply with 80 mA active current and 3 mA standby current - suitable for low-power sleep modes |
Key Features
| Feature | Design Value |
|---|---|
| Fast 3 ms page write | Reduces firmware update time by >65% vs. 10 ms variants, enabling faster field reprogramming in production test and service workflows |
| DATA Polling on I/O7 | Allows host MCU to detect write completion without fixed delays - eliminates need for timeout-based polling loops |
| Software Data Protection (SDP) | Three-byte unlock sequence prevents accidental writes during power transitions or noise events, enhancing system robustness |
| JEDEC byte-wide pinout | Ensures drop-in compatibility with legacy 27C256, 28C256, and other parallel EPROM/EEPROM sockets in existing PCB designs |
| Industrial temperature range | Validated operation from –40°C to +85°C supports deployment in motor drives, PLCs, and environmental monitoring equipment |
Applications
| Industrial PLC Configuration Storage | Medical Device Calibration Data Retention |
|---|---|
Use Scenario: Storing I/O mapping tables, PID tuning parameters, and alarm thresholds in programmable logic controllers deployed in factory automation. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed via 8-bit parallel bus during controller boot and runtime parameter updates. Use Value: 3 ms page write enables rapid recalibration during maintenance windows; 10-year data retention ensures parameter integrity across equipment lifecycle. | Use Scenario: Holding sensor calibration coefficients, user preferences, and regulatory audit logs in portable diagnostic instruments. IC Role / Device Role / Timing Role: Secure, tamper-resistant storage element interfaced to an ARM Cortex-M3 MCU using standard GPIO-controlled parallel bus. Use Value: Software data protection prevents unintended overwrites during battery swaps or ESD events; industrial temp rating supports operation in clinical environments. |
| Automotive Body Control Module (BCM) | Test Equipment Firmware Patch Storage |
Use Scenario: Saving seat/mirror position presets, lighting profiles, and fault history in 12V automotive BCMs operating under wide thermal and voltage variation. IC Role / Device Role / Timing Role: Parallel EEPROM directly mapped into microcontroller address space for zero-wait-state reads during vehicle startup. Use Value: 5V ±10% supply tolerance accommodates automotive battery fluctuations; –40°C to +85°C rating covers under-hood and cabin installations. | Use Scenario: Hosting field-upgradable firmware patches and instrument-specific configuration files in automated test systems with frequent software revisions. IC Role / Device Role / Timing Role: Standalone nonvolatile memory accessed via FPGA or microcontroller for hot-swappable feature updates without reprogramming main flash. Use Value: 64-byte page write minimizes patch application time; DATA polling simplifies host firmware implementation versus fixed-delay write routines. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28HC256-12SI | 10 ms page write time (vs. 3 ms); same pinout, package, and temperature range | Less suitable for time-critical firmware updates; higher write latency increases test cycle time | Select when cost sensitivity outweighs write speed requirements and legacy stock exists |
| MN5Q2565B-12SI | Same 256 Kbit × 8 organization, 120 ns access, but only 1000-cycle endurance and no software data protection | Limited to low-duty-cycle configuration storage; unsuitable for frequent field updates or safety-critical calibration | Consider only for cost-driven consumer applications where long-term reliability is secondary |
Compared with AT28HC256-12SI and MN5Q2565B-12SI, the AT28HC256F-12SI delivers superior write performance and enhanced data integrity features - making it optimal for industrial and medical systems requiring rapid, secure, and durable nonvolatile storage.
Availability
AT28HC256F-12SI is available at Aetrix Electronics and suitable for industrial control systems, medical instrumentation, automotive body electronics, and automated test equipment requiring stable component supply and long-term manufacturing continuity.
Supply support for AT28HC256F-12SI 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, delivering high-reliability parallel EEPROMs for legacy-compatible and upgrade-path designs.
The AT28HC256 product line was engineered for embedded systems requiring pin-compatible replacement of EPROMs and early EEPROMs, emphasizing robustness, ease of integration, and long-term data integrity in harsh environments.
FAQ
What is the page write cycle time specification for AT28HC256F-12SI?
The AT28HC256F-12SI has a maximum page write cycle time of 3 ms, confirmed in Section 16 of the datasheet. This is the "Fast Write Option" (suffix F) distinguishing it from the standard 10 ms variant. The 3 ms timing applies across the full industrial temperature range (–40°C to +85°C) and is guaranteed under VCC = 5 V ±10%. AT28HC256F-12SI achieves this via optimized internal charge pump and control logic.
Does AT28HC256F-12SI support software data protection, and how is it enabled?
Yes, AT28HC256F-12SI supports software data protection (SDP) using a three-byte unlock sequence: write AAh to address 5555h, 55h to 2AAAh, then A0h to 5555h. After this sequence, all subsequent writes require repeating the unlock. SDP remains active through power cycles and is disabled only by the dedicated disable sequence (AAh→55h→80h→AAh→20h). AT28HC256F-12SI ships with SDP disabled by default.
What package type and pin count does AT28HC256F-12SI use?
AT28HC256F-12SI uses a 28-lead, 0.300" wide plastic gull-wing small outline (SOIC-28) package, designated as 28S in Microchip's ordering matrix. It conforms to JEDEC standard MS-013, with 1.27 mm lead pitch and surface-mount footprint. Pin 1 is marked by a notch or dot; pins 1–14 and 15–28 are on opposite sides, matching JEDEC byte-wide parallel EEPROM layouts.
How is write completion detected on AT28HC256F-12SI?
AT28HC256F-12SI supports two hardware methods: DATA Polling on I/O7 (complement of last written byte appears until write completes) and Toggle Bit on I/O6 (toggles between 0 and 1 during write, stabilizes when complete). Both methods allow the host to poll asynchronously without fixed delays. AT28HC256F-12SI requires no external components for either method - functionality is fully internal.
Is AT28HC256F-12SI compatible with 5V TTL and CMOS logic families?
Yes, AT28HC256F-12SI features CMOS and TTL compatible inputs and outputs per datasheet Section 1. Input thresholds meet TTL (VIL ≤ 0.8 V, VIH ≥ 2.0 V) and CMOS (VIH ≥ 70% VCC) standards. Output drive strength supports 6 mA sink (VOL ≤ 0.45 V) and 4 mA source (VOH ≥ 2.4 V at VCC = 5 V), ensuring reliable interfacing with 8051, PIC, and legacy microcontrollers without level shifters. AT28HC256F-12SI operates natively at 5 V ±10%.
AT28HC256F-12SI 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:
- -40°C ~ 85°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-SOIC
AT28HC256F-12SI FAQ
1.How can I place an order for AT28HC256F-12SI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28HC256F-12SI 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-12SI reliable?
The price and inventory of AT28HC256F-12SI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28HC256F-12SI is usually 5 days.
3.What payment methods are accepted for AT28HC256F-12SI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28HC256F-12SI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28HC256F-12SI?
AT28HC256F-12SI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28HC256F-12SI 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-12SI?
For technical support, including AT28HC256F-12SI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28HC256F-12SI requirements.
6.How does Aetrix verify that AT28HC256F-12SI is sourced from the original manufacturer or authorized distributors?
All AT28HC256F-12SI 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-12SI meets industry standards.
7.What is the process for return or replacement of AT28HC256F-12SI?
All AT28HC256F-12SI units undergo pre-shipment inspection (PSI). If there is an issue with AT28HC256F-12SI, 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-12SI part is unused and in its original packaging.
Return procedure for AT28HC256F-12SI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT28HC256F-12SI Tags
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M24C02-WMN6TP
STMicroelectronics
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AT24C02C-XHM-T
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AT21CS01-STUM10-T
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24LC01BT-I/OT
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M24C02-FMC6TG
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AT24CS02-SSHM-T
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93LC46BT-I/OT
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AT24C04C-SSHM-T
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24LC01BT-I/SN
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24AA02UIDT-I/OT
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AT24C08C-STUM-T
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