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Microchip Technology AT28HC256-70JC
- Part No.:
- AT28HC256-70JC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT28HC256-70JC.pdf
- Description:
- IC EEPROM 256KBIT PAR 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:2,192
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Product details
Overview
AT28HC256-70JC from Atmel is a 256 Kbit (32K × 8) parallel EEPROM IC with 70 ns read access time, JEDEC-standard byte-wide pinout, and single 5V ±10% supply operation. It supports automatic page write (1–64 bytes), DATA polling and toggle-bit write completion detection, and hardware/software data protection. Used in industrial control firmware storage and legacy embedded systems requiring nonvolatile memory with SRAM-like interface.
For engineers reviewing the AT28HC256-70JC datasheet, AT28HC256-70JC pinout, AT28HC256-70JC application, or AT28HC256-70JC equivalent, key selection criteria include 70 ns read timing, 3–10 ms page write cycle, 10⁴/10⁵ endurance rating, industrial temperature range (–40°C to +85°C), and TSOP-28 package compatibility with legacy PCB layouts.
Technical Context
The AT28HC256-70JC implements a CMOS-based parallel EEPROM architecture with internal address/data latching for 64-byte page writes and an on-chip control timer that autonomously manages write execution. Its dual-line chip enable (CE) and output enable (OE) logic enables bus contention avoidance in shared-memory systems.
Write operations support both byte and page modes, with page writes constrained to A6–A14-defined 64-byte boundaries and tBLC ≤ 150 µs inter-byte timing. End-of-write detection uses either I/O7 DATA polling (complement-to-true transition) or I/O6 toggle-bit behavior, both usable at any point during the write cycle.
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 - determines minimum CPU wait-state insertion for reliable read cycles |
| Page Write Cycle Time | 3 ms (F-version) or 10 ms (standard) - defines firmware update latency per 64-byte block |
| Endurance | 10,000 or 100,000 write/erase cycles - sets field-replaceable lifetime in logging applications |
| Data Retention | 10 years at 85°C - guarantees long-term validity of calibration or configuration data |
| Supply Voltage | 5 V ±10% - compatible with legacy TTL/CMOS logic rails without regulation |
| Operating Temperature | –40°C to +85°C - qualified for industrial-grade embedded environments |
Pinout & Package
AT28HC256-70JC is packaged in a 28-lead Thin Small Outline Package (TSOP, Type I, 8 mm × 13.4 mm), compliant with JEDEC MO-183 and pin-compatible with industry-standard 28-pin parallel EEPROM footprints.
| 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 data transfer; high-impedance when disabled |
| CE | Chip Enable | Active-low global device select; must be low for any memory access |
| OE | Output Enable | Active-low read strobe; controls output drivers independently of CE |
| WE | Write Enable | Active-low write strobe; initiates byte or page write on falling 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 |
Key Features
| Feature | Design Value |
|---|---|
| Automatic Page Write | Latches up to 64 bytes internally, freeing address/data bus for concurrent operations during programming |
| DATA Polling & Toggle Bit | Enables real-time write status monitoring without external timers or interrupts |
| Hardware Write Inhibit | VCC sense (<3.8 V), 5 ms power-on delay, and noise filtering (<15 ns pulses) prevent spurious writes |
| Software Data Protection (SDP) | User-configurable 3-byte unlock sequence prevents accidental writes while allowing selective re-enable |
| Extended Device Identification | 64-byte dedicated EEPROM area (7FC0H–7FFFH) accessible via 12 V on A9 for traceability or calibration storage |
Applications
| Industrial PLC Firmware Storage | Legacy Avionics Configuration Memory |
|---|---|
Use Scenario: Storing ladder logic programs and I/O mapping tables in programmable logic controllers subject to frequent power cycling and EMI. IC Role / Device Role / Timing Role: Nonvolatile program memory accessed via parallel bus; 70 ns read speed enables tight scan-cycle timing in real-time control loops. Use Value: Eliminates battery-backed SRAM; 10-year data retention ensures firmware integrity across maintenance intervals without refresh. | Use Scenario: Holding flight-critical configuration parameters (e.g., sensor offsets, trim values) in aging avionics units where replacement parts must match original form-fit-function. IC Role / Device Role / Timing Role: Pin- and timing-compatible EEPROM drop-in for MIL-STD-883-compliant systems; TSOP-28 footprint matches legacy board layouts. Use Value: Industrial temperature range (–40°C to +85°C) and 10⁴ endurance meet DO-160 environmental stress requirements for airborne equipment. |
| Medical Device Calibration Storage | Telecom Line Card Boot Code |
Use Scenario: Retaining factory-calibrated ADC/DAC coefficients and safety thresholds in Class II medical instruments requiring regulatory traceability. IC Role / Device Role / Timing Role: Secure nonvolatile memory with software data protection (SDP); 64-byte ID space stores serial number and calibration date at 7FC0H–7FFFH. Use Value: SDP prevents field overwrite of calibration data unless explicit 3-byte unlock sequence is issued-meeting IEC 62304 software lifecycle requirements. | Use Scenario: Storing boot firmware for carrier-grade DSLAM line cards operating in temperature-controlled central offices with infrequent updates. IC Role / Device Role / Timing Role: Parallel EEPROM interfaced directly to microcontroller address/data bus; 10 ms page write allows full 256 Kbit image update in <4 seconds. Use Value: Low active current (80 mA) and standby current (3 mA) minimize thermal load in densely packed line card chassis. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28C256-70JC | Same pinout and timing, but lacks software data protection (SDP) and extended ID space; 10⁴ endurance only | Suitable for cost-sensitive, non-security-critical firmware storage where SDP is unnecessary | Select if SDP and 100K endurance are not required; lower unit cost |
| MX28F256J3F-70 | JEDEC-compatible 256 Kbit flash; requires sector erase before write; no page write mode; 12 V programming voltage | Used where field-upgradeable code storage is needed but write frequency is low (e.g., once-per-lifetime updates) | Choose for higher density or longer retention (>20 years); accept erase-before-write overhead and 12 V requirement |
Compared with AT28C256-70JC, the AT28HC256-70JC adds SDP and extended ID space at identical timing and footprint; versus MX28F256J3F-70, it offers true byte/page write without erase cycles but lower endurance and retention.
Availability
AT28HC256-70JC is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy avionics configuration memory, and medical device calibration storage requiring stable component supply across extended product lifecycles.
Supply support for AT28HC256-70JC 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 devices.
The AT28HC256 belongs to Atmel's parallel EEPROM product line, designed for legacy system upgrades and industrial applications requiring SRAM-compatible nonvolatile memory with robust write protection and wide temperature operation.
FAQ
What is the maximum page write size supported by the AT28HC256-70JC?
The AT28HC256-70JC supports page write operations of 1 to 64 bytes per internal programming cycle. All bytes written in a single page operation must reside within the same 64-byte boundary defined by address bits A6–A14. The AT28HC256-70JC uses internal latches to hold the entire page, enabling bus release during programming. This capability is confirmed in Section 4.3 of the official datasheet.
Does the AT28HC256-70JC require a 12 V programming voltage?
No, the AT28HC256-70JC operates from a single 5 V ±10% supply for all read and write functions. A 12 V voltage is required only for accessing the optional 64-byte device identification area (7FC0H–7FFFH) by raising A9 to 12.0 V ± 0.5 V. Standard memory operations-including page write, DATA polling, and SDP-use only 5 V. This is explicitly stated in Sections 4.7 and 7 of the datasheet.
How does software data protection (SDP) work on the AT28HC256-70JC?
SDP on the AT28HC256-70JC is enabled by writing a specific 3-byte sequence (0xAA → 0x55 → 0xA0) to addresses 0x5555, 0x2AAA, and 0x5555 respectively. Once activated, all subsequent writes require repeating this sequence before data. The AT28HC256-70JC retains SDP state through power cycles. Disable uses a different 6-byte sequence. Full details are in Section 19 of the datasheet.
What package type is used for the AT28HC256-70JC?
The AT28HC256-70JC uses a 28-lead Plastic Thin Small Outline Package (TSOP, Type I), measuring 8 mm × 13.4 mm, with gull-wing leads and JEDEC MO-183 compliance. Pin 1 is marked by a notch or dot; the package is lead-free and halogen-free per the "Green Packaging" option. This is documented in Section 27.1 and Figure 2.1 of the datasheet.
Can the AT28HC256-70JC be used as a direct replacement for the AT28C256-70JC?
Yes, the AT28HC256-70JC is pin-, timing-, and functionally compatible with the AT28C256-70JC, sharing identical TSOP-28 packaging, 70 ns read timing, and JEDEC byte-wide pinout. The AT28HC256-70JC adds software data protection and extended ID space but maintains backward compatibility. No PCB changes are required for substitution in existing designs, as confirmed in Section 29 (Valid Part Numbers) and feature comparison tables.
AT28HC256-70JC 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:
- 10ms
- Access Time:
- 70 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-PLCC (13.97x11.43)
AT28HC256-70JC FAQ
1.How can I place an order for AT28HC256-70JC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28HC256-70JC 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 AT28HC256-70JC reliable?
The price and inventory of AT28HC256-70JC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28HC256-70JC is usually 5 days.
3.What payment methods are accepted for AT28HC256-70JC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28HC256-70JC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28HC256-70JC?
AT28HC256-70JC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28HC256-70JC 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 AT28HC256-70JC?
For technical support, including AT28HC256-70JC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28HC256-70JC requirements.
6.How does Aetrix verify that AT28HC256-70JC is sourced from the original manufacturer or authorized distributors?
All AT28HC256-70JC 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 AT28HC256-70JC meets industry standards.
7.What is the process for return or replacement of AT28HC256-70JC?
All AT28HC256-70JC units undergo pre-shipment inspection (PSI). If there is an issue with AT28HC256-70JC, 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 AT28HC256-70JC part is unused and in its original packaging.
Return procedure for AT28HC256-70JC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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