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Microchip Technology AT28HC256F-12TI
- Part No.:
- AT28HC256F-12TI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-TSSOP (0.465", 11.80mm Width)
- Datasheet:
-
AT28HC256F-12TI.pdf
- Description:
- IC EEPROM 256KBIT PAR 28TSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,788
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Product details
Overview
AT28HC256F-12TI from Microchip Technology (formerly Atmel) is a 256 Kbit (32K × 8) parallel EEPROM IC used for nonvolatile program/data storage in embedded control and instrumentation systems. It features 70 ns read access time, 3 ms page write cycle, 5V ±10% single-supply operation, JEDEC-standard byte-wide pinout, and industrial temperature range (–40°C to +85°C).
For engineers reviewing the AT28HC256F-12TI datasheet, AT28HC256F-12TI pinout, AT28HC256F-12TI application, or AT28HC256F-12TI equivalent, this page delivers verified electrical specs, validated pin functions, confirmed industrial-grade reliability data, and real-world use cases for legacy system upgrades, firmware storage, and configuration retention.
Technical Context
The AT28HC256F-12TI implements a CMOS-based parallel EEPROM architecture with internal 64-byte page latching and autonomous write timing. Its dual-line chip enable (CE) and output enable (OE) control enables bus contention avoidance in shared-memory systems.
It supports both byte and page write modes, with DATA Polling (I/O7 complement) and Toggle Bit (I/O6 toggling) for end-of-write detection. Hardware write protection includes VCC sense, 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), sufficient for boot code or calibration tables in microcontroller-based systems |
| Read Access Time | 120 ns max - compatible with 8 MHz Z80, 68K, or early ARM bus timing |
| Page Write Cycle Time | 3 ms max - enables rapid field updates of up to 64 bytes without external timing logic |
| Endurance | 10,000 write/erase cycles - validated for infrequent configuration changes over 10+ years |
| Data Retention | 10 years at +85°C - meets industrial equipment shelf-life and long-term deployment requirements |
| Supply Voltage | 5V ±10% - interoperable with legacy TTL/CMOS logic families without level shifting |
| Operating Temperature | –40°C to +85°C - qualified for industrial control panels, motor drives, and test equipment |
Pinout & Package
AT28HC256F-12TI is housed in a 28-lead Plastic Thin Small Outline Package (TSOP), Type I (8 mm × 13.4 mm), compliant with JEDEC MO-183. Pin 1 identifier is marked by a beveled corner.
| 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 writes |
| I/O0–I/O7 | Bidirectional Data Bus | CMOS/TTL-compatible 8-bit parallel interface; supports true read/write without external transceivers |
| CE | Chip Enable | Active-low device select; must be low with OE low and WE high for read access |
| OE | Output Enable | Active-low output control; enables high-impedance state when high to prevent bus contention |
| WE | Write Enable | Active-low write strobe; falling edge latches address and data for byte or page programming |
| VCC | Power Supply | +5V ±10% supply; internal VCC sense disables writes below ~3.8V for power-fail safety |
| GND | Ground Reference | Signal and power return; decoupling capacitor required within 10 mm of VCC/GND pins |
Key Features
| Feature | Design Value |
|---|---|
| Automatic Page Write | Internal 64-byte latch and timer eliminate external write-cycle management logic |
| DATA Polling & Toggle Bit | Real-time write completion detection via I/O7 complement or I/O6 toggling - no polling overhead on host CPU |
| Hardware + Software Data Protection | VCC-sense, noise filtering, and 3-byte SDP command sequence prevent accidental writes during power transitions |
| JEDEC Byte-Wide Pinout | Drop-in replacement for industry-standard 27C256/28C256 sockets - no PCB redesign needed |
| Industrial Temperature Range | –40°C to +85°C operation with guaranteed 120 ns access and 3 ms write - suitable for uncooled enclosures |
Applications
| Industrial PLC Configuration Storage | Legacy Instrumentation Firmware Retention |
|---|---|
Use Scenario: Storing user-defined I/O mapping, scaling coefficients, and alarm thresholds in programmable logic controllers deployed in factory automation. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed during power-up and runtime reconfiguration; reads occur at system initialization, writes only during parameter update. Use Value: Eliminates battery-backed SRAM; retains settings across 10+ years and 10,000 field updates without maintenance. | Use Scenario: Holding calibrated sensor offset/gain values and firmware patches in benchtop multimeters and oscilloscopes. IC Role / Device Role / Timing Role: Parallel EEPROM interfaced directly to 8-bit microcontrollers (e.g., 8051 derivatives); supports in-field firmware patching via RS-232. Use Value: Enables field-upgradable calibration data without requiring full board replacement or specialized programmers. |
| Embedded System Boot Code Storage | Telecom Line Card Parameter Memory |
Use Scenario: Storing bootloader code and hardware initialization routines for microcontrollers in HVAC controllers and energy meters. IC Role / Device Role / Timing Role: Memory-mapped boot ROM accessed at reset vector; read-only during normal operation, write-protected except during firmware upgrade. Use Value: Provides deterministic boot behavior and secure firmware integrity using hardware write inhibit and SDP. | Use Scenario: Retaining line impedance profiles, gain settings, and diagnostic logs in DSLAM and PON line cards operating in telecom central offices. IC Role / Device Role / Timing Role: Configuration EEPROM connected to local MCU; accessed during card insertion and periodic health checks. Use Value: Ensures consistent line performance across hot-swap events and maintains service continuity during power cycling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28HC256-12TI | 10 ms page write cycle vs. 3 ms; same pinout, package, voltage, and temperature rating | Slower write speed limits use in time-critical field updates; otherwise identical functionality | Select when write frequency is low and cost sensitivity outweighs speed requirement |
| MX28F256J3F | JEDEC-standard 28-pin PLCC package; 120 ns access; 5V-only; 10K endurance; no software data protection | Lacks SDP and toggle-bit detection; requires external write timing control | Choose for legacy PLCC socket compatibility where simplified firmware control is acceptable |
Compared with AT28HC256-12TI, the AT28HC256F-12TI reduces page write time by 70%, enabling faster field updates; versus MX28F256J3F, it adds robust write protection and autonomous end-of-write signaling - critical for unattended industrial deployments.
Availability
AT28HC256F-12TI is available at Aetrix Electronics and suitable for industrial control, legacy instrumentation, and telecom infrastructure applications requiring stable component supply, long-term lifecycle support, and guaranteed industrial-temperature performance.
Supply support for AT28HC256F-12TI 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, errata, and long-term manufacturing commitments.
The AT28HC256 product line was designed for reliable, pin-compatible replacement of UV-erasable EPROMs and early serial EEPROMs in space-constrained industrial and military systems requiring parallel interface simplicity and proven nonvolatile storage.
FAQ
What is the maximum page write time for AT28HC256F-12TI?
The AT28HC256F-12TI has a maximum page write cycle time of 3 ms, as specified in the "Page Mode Write Characteristics" table. This is the Fast Write Option (suffix 'F') variant, distinct from the standard 10 ms version. The 3 ms timing applies across the full industrial temperature range (–40°C to +85°C) and is internally controlled - no external timing components are required. AT28HC256F-12TI achieves this via optimized charge-pump circuitry and reduced programming voltage thresholds.
Does AT28HC256F-12TI support software data protection?
Yes, AT28HC256F-12TI supports Software Data Protection (SDP) via a documented 3-byte command sequence written to specific addresses (0x5555, 0x2AAA, 0x5555). Once enabled, all subsequent writes require reissuing the sequence. SDP remains active through power cycles and protects against inadvertent writes during brown-out conditions. AT28HC256F-12TI ships with SDP disabled by default, and the feature is fully functional per the "Software Data Protection" section of the datasheet.
What package type is used for AT28HC256F-12TI?
AT28HC256F-12TI uses a 28-lead Plastic Thin Small Outline Package (TSOP), Type I, with dimensions 8 mm × 13.4 mm and 0.55 mm lead pitch. This package is JEDEC MO-183 compliant and features gull-wing leads. Pin 1 is identified by a beveled corner on the top surface. The TSOP package provides superior thermal performance and board-space efficiency compared to PDIP or SOIC variants, making it ideal for compact industrial modules.
Can AT28HC256F-12TI be used as a direct replacement for AT28HC256-12TI?
Yes, AT28HC256F-12TI is a pin- and function-compatible drop-in replacement for AT28HC256-12TI, sharing identical package (28T TSOP), pinout, voltage, temperature range, and read timing. The only functional difference is the reduced 3 ms page write time (vs. 10 ms), which does not affect read operation or interface compatibility. All control signals (CE, OE, WE), address/data bus behavior, and protection features operate identically. AT28HC256F-12TI requires no PCB or firmware changes.
How is end-of-write detection implemented in AT28HC256F-12TI?
AT28HC256F-12TI provides two independent end-of-write detection methods: DATA Polling (monitoring I/O7 for complement-to-data transition) and Toggle Bit (observing I/O6 toggling until stabilization). Both methods are active during any write cycle (byte or page) and can be polled at any time - no fixed delay is required. These mechanisms eliminate the need for external timers or status registers, simplifying host firmware. AT28HC256F-12TI guarantees valid data on all outputs immediately after either signal indicates completion.
AT28HC256F-12TI Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-TSSOP (0.465", 11.80mm Width)
- Packaging:
- Tray
- 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-TSOP
AT28HC256F-12TI FAQ
1.How can I place an order for AT28HC256F-12TI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28HC256F-12TI 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-12TI reliable?
The price and inventory of AT28HC256F-12TI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28HC256F-12TI is usually 5 days.
3.What payment methods are accepted for AT28HC256F-12TI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28HC256F-12TI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28HC256F-12TI?
AT28HC256F-12TI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28HC256F-12TI 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-12TI?
For technical support, including AT28HC256F-12TI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28HC256F-12TI requirements.
6.How does Aetrix verify that AT28HC256F-12TI is sourced from the original manufacturer or authorized distributors?
All AT28HC256F-12TI 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-12TI meets industry standards.
7.What is the process for return or replacement of AT28HC256F-12TI?
All AT28HC256F-12TI units undergo pre-shipment inspection (PSI). If there is an issue with AT28HC256F-12TI, 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-12TI part is unused and in its original packaging.
Return procedure for AT28HC256F-12TI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT28HC256F-12TI Tags
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M24C02-WMN6TP
STMicroelectronics
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AT24C02C-XHM-T
Microchip Technology
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AT21CS01-STUM10-T
Microchip Technology
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AT24C02C-SSHM-T
Microchip Technology
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24LC01BT-I/OT
Microchip Technology
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M24C02-FMC6TG
STMicroelectronics
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AT24CS02-SSHM-T
Microchip Technology
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93LC46BT-I/OT
Microchip Technology
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AT24C04C-SSHM-T
Microchip Technology
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24LC01BT-I/SN
Microchip Technology
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24AA02UIDT-I/OT
Microchip Technology
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AT24C08C-STUM-T
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