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Microchip Technology AT28HC256-70PI
- Part No.:
- AT28HC256-70PI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-DIP (0.600", 15.24mm)
- Datasheet:
-
AT28HC256-70PI.pdf
- Description:
- IC EEPROM 256KBIT PARALLEL 28DIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,012
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Product details
Overview
AT28HC256-70PI from Atmel is a 256 Kbit (32K × 8) parallel EEPROM IC designed for nonvolatile data storage in embedded control and instrumentation systems. It delivers 70 ns read access time, supports 1–64-byte page writes with internal latching and timer control, operates on single 5V ±10% supply, and features hardware/software write protection. It is used in industrial PLCs for firmware parameter retention.
For engineers reviewing the AT28HC256-70PI datasheet, AT28HC256-70PI pinout, AT28HC256-70PI application, or AT28HC256-70PI equivalent, key selection criteria include JEDEC byte-wide pin compatibility, 70 ns read timing, industrial temperature range (−40°C to +85°C), page-write endurance (10⁴ cycles), and DATA Polling/Toggle Bit write completion detection.
Technical Context
The AT28HC256-70PI implements a CMOS-based parallel EEPROM architecture with dual-line chip enable (CE) and output enable (OE) control, enabling bus contention avoidance in shared-memory systems. Its internal 64-byte page register latches address and data during write initiation, freeing the bus for concurrent operations.
Write completion is verified via two independent methods: DATA Polling (I/O7 complement-to-data behavior) and Toggle Bit (I/O6 toggling during active programming). Hardware protection includes VCC sense (<3.8 V inhibits write), 5 ms power-on delay, noise filtering (<15 ns pulses rejected), and CE/OE/WE state locking.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8), organized as byte-addressable parallel array |
| Read Access Time | 70 ns maximum - enables direct replacement of SRAM in legacy 5 MHz bus systems |
| Page Write Cycle Time | 10 ms maximum - defines minimum interval between successive page write initiations |
| Endurance | 10,000 write/erase cycles - validated for firmware update logging in field-deployed controllers |
| Data Retention | 10 years at +85°C - ensures long-term calibration data integrity in unattended industrial sensors |
| Supply Voltage | 5 V ±10% - compatible with standard TTL/CMOS logic rails without regulation overhead |
| Operating Temperature | −40°C to +85°C - qualified for industrial-grade PCB mounting without derating |
| Standby Current | 60 mA max (TTL-level CE) - impacts low-power sleep mode budget in battery-backed systems |
Pinout & Package
AT28HC256-70PI is supplied in a 28-lead plastic dual in-line package (PDIP), 0.600" wide, 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 selecting one of 32,768 memory locations |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel interface for read/write transfers; high-impedance when disabled |
| CE | Chip Enable | Active-low device select; must be low for any memory access (read or write) |
| OE | Output Enable | Active-low control for output drivers; allows read-only bus sharing with other devices |
| WE | Write Enable | Active-low signal initiating byte or page write; latches data on rising edge |
| VCC | Power Supply | +5 V ±10% main supply; powers core logic and I/O buffers |
| GND | Ground Reference | Signal and power return path; decoupling required within 1 cm of VCC pin |
| NC | No Connect | Pins 1 and 17 in PLCC variant only - not present in PDIP (AT28HC256-70PI uses PDIP) |
Key Features
| Feature | Design Value |
|---|---|
| Automatic Page Write | Internal 64-byte latch and timer eliminate external write sequencing logic and reduce MCU firmware overhead |
| DATA Polling & Toggle Bit | Dual, hardware-verified write completion detection avoids fixed delays and improves system throughput |
| Hardware Write Inhibit | VCC sense, power-on delay, and noise filtering prevent spurious writes during brown-out or EMI events |
| Software Data Protection (SDP) | User-configurable 3-byte command sequence prevents accidental overwrites without hardware modification |
| JEDEC Byte-wide Pinout | Direct drop-in compatibility with industry-standard 28-pin parallel EEPROM footprints and PCB layouts |
| Industrial Temperature Range | −40°C to +85°C operation validated per MIL-STD-883 test conditions for extended field life |
Applications
| Industrial PLC Configuration Storage | Automotive Engine Control Module Calibration |
|---|---|
Use Scenario: Storing user-modified I/O mapping and PID tuning parameters in programmable logic controllers deployed in factory automation lines. IC Role / Device Role / Timing Role: Nonvolatile configuration register accessed via 8-bit parallel bus during boot and runtime reconfiguration. Use Value: 70 ns read speed enables real-time parameter recall without interrupting scan cycle timing; page write reduces firmware update latency by 94% vs. byte-by-byte writes. | Use Scenario: Retaining fuel trim and knock sensor compensation tables across ignition cycles in Tier-1 automotive ECUs. IC Role / Device Role / Timing Role: High-reliability calibration memory mapped into microcontroller address space with hardware write lock during engine run. Use Value: 10-year data retention at +85°C ensures calibration validity over full vehicle service life; VCC-sense protection prevents corruption during cranking voltage sag. |
| Medical Infusion Pump Safety Logs | Telecom Base Station Bootloader Image |
Use Scenario: Recording dose history, alarm events, and operator actions in Class II medical infusion pumps requiring FDA audit trails. IC Role / Device Role / Timing Role: Secure, tamper-evident event log storage with software data protection enabled during normal operation. Use Value: SDP command sequence prevents unauthorized log erasure; 10⁴ endurance supports >5 years of continuous 10-event-per-minute logging. | Use Scenario: Holding field-upgradable bootloader code in wireless base station remote radio units exposed to outdoor thermal cycling. IC Role / Device Role / Timing Role: Read-critical boot memory accessed at power-on reset before FPGA or DSP initialization. Use Value: JEDEC pinout ensures backward compatibility with legacy board designs; −40°C to +85°C rating eliminates need for local heating/cooling in enclosure. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28C256-70PI | Same pinout and timing, but lacks software data protection and page write; 10 ms write only, no 3 ms option | Suitable for cost-sensitive, low-security applications where firmware updates are infrequent and controlled | Select when SDP and fast page write are unnecessary and BOM cost reduction is primary |
| MX28F256J3F-70PC | 32-pin PLCC, 70 ns access, 3 ms page write, but requires 12 V for chip erase and lacks DATA Polling | Used in military avionics where radiation tolerance and extended temperature are critical | Choose only if PLCC footprint and 12 V support infrastructure exist; not pin-compatible with AT28HC256-70PI PDIP |
Compared with AT28HC256-70PI, AT28C256-70PI offers identical industrial PDIP packaging and timing but omits advanced write safeguards, while MX28F256J3F-70PC provides faster writes in a different package with higher voltage requirements-neither is a drop-in replacement without layout or firmware changes.
Availability
AT28HC256-70PI is available at Aetrix Electronics and suitable for industrial control systems, automotive ECU calibration storage, and medical device safety logging requiring stable component supply across extended product lifecycles.
Supply support for AT28HC256-70PI 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
Atmel Corporation (now part of Microchip Technology) is a semiconductor manufacturer specializing in microcontrollers, nonvolatile memory, and secure authentication ICs.
The AT28HC256 product line was engineered for high-reliability, byte-erasable parallel EEPROM applications in industrial, automotive, and medical systems where firmware flexibility and data integrity are critical.
FAQ
What is the maximum page write cycle time for AT28HC256-70PI?
The AT28HC256-70PI has a maximum page write cycle time of 10 ms, as specified in its AC characteristics table. This value applies to the standard version (no "F" suffix); the "F" variant reduces this to 3 ms. The 10 ms timing governs the internal programming duration after the final byte is latched, and must be observed before initiating subsequent memory accesses. AT28HC256-70PI does not support sub-10 ms page writes.
Does AT28HC256-70PI support both DATA Polling and Toggle Bit for write completion detection?
Yes, AT28HC256-70PI supports both DATA Polling (via I/O7 complement behavior) and Toggle Bit (via I/O6 toggling) for real-time write status monitoring. These mechanisms operate independently and can be used interchangeably in firmware. Both are fully functional across the full −40°C to +85°C industrial temperature range and require no additional hardware. AT28HC256-70PI's dual-method support increases system robustness compared to EEPROMs offering only one detection method.
What package type is used for AT28HC256-70PI?
AT28HC256-70PI uses a 28-lead plastic dual in-line package (PDIP), 0.600" wide, designated as "28P6" in Atmel's ordering nomenclature. This through-hole package conforms to JEDEC MS-011 AB and is compatible with standard wave-solder and hand-solder processes. It is distinct from TSOP, PLCC, or PGA variants offered in the same family - AT28HC256-70PI specifically ships only in PDIP.
Can AT28HC256-70PI be used as a direct replacement for older AT28C256-70PI devices?
AT28HC256-70PI is pin- and function-compatible with AT28C256-70PI in read operations and basic byte writes, but adds page write capability, software data protection (SDP), and enhanced hardware write inhibit features. No PCB changes are needed for substitution, though firmware may require minor updates to leverage SDP or page write. AT28HC256-70PI maintains identical DC/AC timing and industrial temperature rating, making it a seamless upgrade path for legacy AT28C256-70PI designs.
What is the endurance rating of AT28HC256-70PI, and how is it validated?
AT28HC256-70PI is rated for 10,000 write/erase cycles per memory location, validated per JEDEC JESD22-A117 stress testing methodology. This endurance applies to both byte and page write operations under industrial temperature conditions (−40°C to +85°C) and 5 V ±10% supply. Endurance is not extended by the "E" variant (AT28HC256E), which is not applicable to the -70PI suffix. AT28HC256-70PI's endurance specification is guaranteed across its full operational lifetime without derating.
AT28HC256-70PI Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-DIP (0.600", 15.24mm)
- 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:
- 10ms
- Access Time:
- 70 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 28-PDIP
AT28HC256-70PI FAQ
1.How can I place an order for AT28HC256-70PI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28HC256-70PI 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 AT28HC256-70PI reliable?
The price and inventory of AT28HC256-70PI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28HC256-70PI is usually 5 days.
3.What payment methods are accepted for AT28HC256-70PI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28HC256-70PI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28HC256-70PI?
AT28HC256-70PI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28HC256-70PI 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 AT28HC256-70PI?
For technical support, including AT28HC256-70PI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28HC256-70PI requirements.
6.How does Aetrix verify that AT28HC256-70PI is sourced from the original manufacturer or authorized distributors?
All AT28HC256-70PI 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 AT28HC256-70PI meets industry standards.
7.What is the process for return or replacement of AT28HC256-70PI?
All AT28HC256-70PI units undergo pre-shipment inspection (PSI). If there is an issue with AT28HC256-70PI, 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 AT28HC256-70PI part is unused and in its original packaging.
Return procedure for AT28HC256-70PI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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