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Microchip Technology AT28HC256F-70JI
- Part No.:
- AT28HC256F-70JI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT28HC256F-70JI.pdf
- Description:
- IC EEPROM 256KBIT PAR 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:4,814
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Product details
Overview
AT28HC256F-70JI from Microchip Technology (formerly Atmel) is a 256 Kbit (32K × 8) parallel EEPROM with JEDEC-standard byte-wide pinout, 70 ns read access time, 3 ms page write cycle, and industrial temperature range (–40°C to +85°C). 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-70JI datasheet, AT28HC256F-70JI pinout, AT28HC256F-70JI application, or AT28HC256F-70JI equivalent, key selection criteria include fast 70 ns read timing, 3 ms page write capability, industrial-grade reliability (10⁴ write cycles, 10-year data retention), and compatibility with legacy SRAM-based memory interfaces.
Technical Context
The AT28HC256F-70JI implements a CMOS-based parallel EEPROM architecture with internal 64-byte page latches and an 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.
It supports three end-of-write detection methods: DATA Polling (I/O7 complement), Toggle Bit (I/O6 toggling), and software-controlled timeout. Hardware write inhibition activates below 3.8 VCC, during power-up delay (~5 ms), or when OE high/CE high/WE high - ensuring robust immunity to spurious writes during power transitions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8), organized as byte-addressable nonvolatile storage |
| Read Access Time | 70 ns maximum - enables direct replacement of 70 ns SRAM in legacy designs without timing redesign |
| Page Write Cycle | 3 ms typical - reduces firmware update latency vs. standard 10 ms variants |
| Supply Voltage | 5 V ±10% - compatible with standard TTL/CMOS logic rails and eliminates need for auxiliary voltage regulators |
| Operating Temperature | –40°C to +85°C - qualified for industrial control, automotive body electronics, and factory automation |
| Endurance & Retention | 10,000 write/erase cycles minimum; 10 years data retention at 85°C - validated for long-life field deployments |
| Power Dissipation | 80 mA active current; 3 mA standby current - supports low-power sleep modes in battery-backed systems |
Pinout & Package
AT28HC256F-70JI is supplied in a 28-lead plastic dual-inline package (PDIP), 0.600" wide (28P6), with JEDEC-standard byte-wide pinout and through-hole mounting compatibility.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus supporting full 32K-word addressing; A0–A5 select bytes within 64-byte page |
| I/O0–I/O7 | Bi-directional Data Bus | True 8-bit parallel interface; electrically compatible with TTL/CMOS logic levels |
| CE | Chip Enable | Active-low device select; must be low for read/write; high forces outputs to high-impedance state |
| OE | Output Enable | Active-low read control; used with CE to prevent bus contention during multi-device sharing |
| WE | Write Enable | Active-low write strobe; falling edge latches address/data; initiates byte or page programming |
| VCC | Power Supply | +5 V ±10% supply input; includes internal VCC sense circuitry for write inhibition below 3.8 V |
| GND | Ground Reference | Signal and power return path; decoupling capacitor required near VCC pin per layout guidelines |
Key Features
| Feature | Design Value |
|---|---|
| Automatic Page Write | Internal 64-byte latch and timer eliminate external timing logic - simplifies host MCU firmware for bulk writes |
| DATA Polling & Toggle Bit | Dual asynchronous write-completion detection (I/O7 complement / I/O6 toggle) enables deterministic polling without fixed delays |
| Hardware Write Protection | VCC sense, 5 ms power-on delay, and noise filtering (<15 ns pulses rejected) prevent accidental writes during brown-out or EMI events |
| Software Data Protection (SDP) | User-configurable 3-byte unlock sequence (AAh/55h/A0h) enables selective write-enable - critical for bootloader-safe firmware updates |
| Extended Identification Area | 64-byte dedicated EEPROM region (7FC0h–7FFFh) accessible via 12 V on A9 - supports unique device serialization and calibration storage |
Applications
| Industrial PLC Firmware Storage | Automotive Body Control Module (BCM) |
|---|---|
Use Scenario: Storing configuration parameters and calibration data in programmable logic controllers operating in harsh factory environments. IC Role / Device Role / Timing Role: Nonvolatile memory for persistent storage of user-defined ladder logic settings and sensor offset tables. Use Value: 10,000-cycle endurance and –40°C to +85°C operation ensure reliable reprogramming over 10+ years of continuous industrial use. | Use Scenario: Holding door lock actuator profiles and lighting dimming curves in vehicle BCMs requiring field-upgradable behavior. IC Role / Device Role / Timing Role: Parallel EEPROM interfaced directly to 8-bit microcontrollers for fast read access during boot and runtime parameter recall. Use Value: 70 ns read timing matches legacy MCU bus speeds; 3 ms page write enables sub-100 ms OTA firmware patching without system interruption. |
| Medical Device Calibration Memory | Telecom Line Card Configuration |
Use Scenario: Storing sensor gain/offset coefficients and regulatory compliance logs in Class II medical instruments with traceability requirements. IC Role / Device Role / Timing Role: Secure, tamper-resistant nonvolatile storage with hardware/software write locks to prevent unauthorized calibration changes. Use Value: SDP-enabled write protection ensures only authenticated service tools can modify calibration data - meeting IEC 62304 traceability mandates. | Use Scenario: Maintaining port mapping, protocol stack versions, and vendor-specific feature flags across hot-swappable telecom line cards. IC Role / Device Role / Timing Role: Byte-addressable parallel memory accessed by FPGA or ARM-based management processors during card initialization. Use Value: JEDEC-standard pinout guarantees drop-in compatibility with existing board designs; 32K × 8 capacity accommodates multi-layer configuration hierarchies. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28HC256-70JI | Standard 10 ms page write cycle; same pinout, voltage, and temperature rating | Lower write speed suitable for infrequent configuration updates where latency is non-critical | Select when cost sensitivity outweighs write performance needs; no PCB change required |
| AT28HC256F-90JI | 90 ns read access; identical 3 ms page write; same industrial temp grade and package | Relaxed read timing allows use with slower clock domains or longer trace lengths | Choose for designs with marginal setup/hold margins or legacy 90 ns timing budgets |
Compared with AT28HC256-70JI, the AT28HC256F-70JI delivers 3× faster page writes while maintaining identical read timing and industrial qualification - making it optimal for field-upgradable systems. Versus AT28HC256F-90JI, it provides tighter 70 ns read timing for high-speed bus integration without sacrificing write performance.
Availability
AT28HC256F-70JI is available at Aetrix Electronics and suitable for industrial control, automotive body electronics, and medical device calibration storage requiring stable component supply and long-term manufacturing continuity.
Supply support for AT28HC256F-70JI 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 legacy Atmel parallel EEPROMs including the AT28HC256 family.
The AT28HC256 product line was designed for pin-compatible replacement of EPROM and SRAM in legacy embedded systems - emphasizing JEDEC compliance, industrial temperature resilience, and simplified firmware update workflows.
FAQ
What is the maximum page write time for AT28HC256F-70JI?
The AT28HC256F-70JI has a maximum page write cycle time of 3 ms, confirmed in the AC Write Characteristics table (Section 16). This is the "Fast Write Option" (suffix F) distinguishing it from the standard 10 ms variant. The 3 ms specification applies across the full industrial temperature range (–40°C to +85°C) and is guaranteed under all valid VCC and timing conditions specified in the datasheet.
Does AT28HC256F-70JI support both hardware and software write protection?
Yes, AT28HC256F-70JI implements dual-layer write protection. Hardware protection includes VCC sensing (<3.8 V inhibits writes), 5 ms power-on delay, and noise filtering on WE/CE inputs. Software Data Protection (SDP) is enabled via a 3-byte unlock sequence (AAh/55h/A0h); once activated, all writes require repetition of this sequence. Both mechanisms operate independently and concurrently in AT28HC256F-70JI.
What package type is used for AT28HC256F-70JI?
AT28HC256F-70JI uses a 28-lead plastic dual-inline package (PDIP), 0.600" wide (ordering code suffix "PI" indicates PDIP; "JI" denotes industrial temperature grade). This is explicitly listed in Section 27.1 of the datasheet under "AT28HC256(E,F)-70PI" and conforms to JEDEC MS-011 AB. Pin 1 is marked by a notch or dot; lead finish is matte tin.
Can AT28HC256F-70JI be used as a direct replacement for standard SRAM in existing designs?
Yes, AT28HC256F-70JI is designed for SRAM-like read access: CE and OE low with WE high asserts data on I/O0–I/O7 within 70 ns. Its JEDEC-standard byte-wide pinout and TTL/CMOS-compatible signaling allow drop-in replacement in many SRAM-based systems - provided write cycles are managed per EEPROM timing (e.g., DATA Polling or Toggle Bit detection) rather than simple bus turnaround.
What is the purpose of the extra 64 bytes of EEPROM in AT28HC256F-70JI?
The AT28HC256F-70JI includes 64 bytes of dedicated identification EEPROM (addresses 7FC0h–7FFFh), accessible by raising A9 to 12 V ±0.5 V. This area is intended for device-specific data such as serial numbers, calibration coefficients, or manufacturing lot codes - separate from main array writes and immune to standard erase commands, enhancing traceability and field-serviceability.
AT28HC256F-70JI 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:
- 3ms
- Access Time:
- 70 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-PLCC (13.97x11.43)
AT28HC256F-70JI FAQ
1.How can I place an order for AT28HC256F-70JI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28HC256F-70JI 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-70JI reliable?
The price and inventory of AT28HC256F-70JI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28HC256F-70JI is usually 5 days.
3.What payment methods are accepted for AT28HC256F-70JI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28HC256F-70JI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28HC256F-70JI?
AT28HC256F-70JI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28HC256F-70JI 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-70JI?
For technical support, including AT28HC256F-70JI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28HC256F-70JI requirements.
6.How does Aetrix verify that AT28HC256F-70JI is sourced from the original manufacturer or authorized distributors?
All AT28HC256F-70JI 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-70JI meets industry standards.
7.What is the process for return or replacement of AT28HC256F-70JI?
All AT28HC256F-70JI units undergo pre-shipment inspection (PSI). If there is an issue with AT28HC256F-70JI, 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-70JI part is unused and in its original packaging.
Return procedure for AT28HC256F-70JI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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