My Inquiry
My Account
Microchip Technology AT28HC256-70JU
- Part No.:
- AT28HC256-70JU
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT28HC256-70JU.pdf
- Description:
- IC EEPROM 256KBIT PAR 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:3,135
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
AT28HC256-70JU from Microchip Technology is a 256-Kbit (32,768 × 8) parallel EEPROM with 70 ns read access time, single 5V ±10% supply, JEDEC-standard byte-wide pinout, and industrial temperature range (–40°C to +85°C). It supports automatic page write (up to 64 bytes), DATA polling, and hardware/software data protection for embedded control and firmware storage applications.
For engineers reviewing the AT28HC256-70JU datasheet, AT28HC256-70JU pinout, AT28HC256-70JU application, or AT28HC256-70JU equivalent, this page delivers verified technical context, real-world use cases, validated alternatives, and supply-chain support for industrial-grade nonvolatile memory selection.
Technical Context
The AT28HC256-70JU operates as a parallel-interface EEPROM with static RAM-like read/write timing and no external timing components required. Its internal 64-byte page register enables burst writes, while VCC-sense and 5 ms power-on delay prevent inadvertent writes during power transitions.
It implements dual end-of-write detection via DATA polling on I/O7 and toggle-bit monitoring on I/O6, and supports optional software data protection using a 3-byte command sequence at fixed addresses (5555H/2AAAH). The device includes 64 bytes of dedicated identification memory accessible at 7FC0H–7FFFH with A9 = 12 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8) - provides sufficient space for boot code, calibration data, or configuration tables in resource-constrained systems |
| Read Access Time | 70 ns - enables direct replacement of SRAM or faster EPROMs in legacy 8-bit microcontroller buses |
| Page Write Cycle | ≤10 ms - allows efficient bulk updates without blocking system bus for extended periods |
| 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 - certified for industrial environments including factory automation and motor control |
| Endurance | 10,000 write cycles - sufficient for infrequent parameter logging or field-upgradeable firmware metadata |
| Data Retention | 10 years - ensures long-term reliability in unpowered storage without battery backup |
Pinout & Package
AT28HC256-70JU is packaged in a 32-lead PLCC (Plastic Leaded Chip Carrier) with JEDEC-standard byte-wide pinout. Pin 1 and Pin 17 are "Don't Connect" (DC); Pins 12 and 26 are No Connect (NC).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus supporting full 32,768-word addressing; A6–A14 define page boundaries for 64-byte writes |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel interface; I/O7 used for DATA polling, I/O6 for toggle-bit status indication |
| CE | Chip Enable | Active-low chip select; must be low with OE low and WE high for read access |
| OE | Output Enable | Active-low output control; high-Z state prevents bus contention when disabled |
| WE | Write Enable | Active-low write strobe; falling edge latches address and data for byte or page write |
| VCC | Power Supply | +5 V ±10% main supply; internal VCC-sense circuit inhibits writes below ~3.8 V |
| GND | Ground Reference | Signal and power ground reference for all I/O and internal logic |
Key Features
| Feature | Design Value |
|---|---|
| Automatic Page Write | 64-byte internal latch reduces host CPU overhead and bus occupancy during firmware updates |
| DATA Polling & Toggle Bit | Dual asynchronous write-completion detection eliminates need for fixed delays or external timers |
| Hardware Write Protection | VCC-sense + 5 ms power-on delay prevents corruption during brown-out or cold-start conditions |
| Software Data Protection | User-configurable 3-byte command sequence blocks accidental writes without hardware modification |
| Device Identification Memory | 64-byte reserved area (7FC0H–7FFFH) accessible at 12 V on A9 for serialization or calibration tracking |
Applications
| Industrial PLC Configuration Storage | Medical Device Calibration Data |
|---|---|
Use Scenario: Storing I/O mapping, PID tuning parameters, and safety thresholds in programmable logic controllers that operate continuously in harsh factory environments. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed via 8-bit parallel bus during boot and runtime reconfiguration; 70 ns read speed ensures minimal scan-time impact. Use Value: 10-year data retention and 10,000-cycle endurance guarantee parameter integrity across equipment lifecycles without battery backup. | Use Scenario: Holding calibrated sensor offsets, gain coefficients, and regulatory audit logs in portable diagnostic instruments requiring traceable, tamper-resistant storage. IC Role / Device Role / Timing Role: Secure parameter vault with software data protection enabled; 12 V A9 programming enables unique device ID injection during final test. Use Value: Hardware+software write protection prevents unintended overwrites during field servicing or firmware updates. |
| Legacy Embedded System Boot Code | Automotive Body Control Module Settings |
Use Scenario: Hosting bootloader code and hardware initialization routines in 8051- or Z80-based industrial controllers where flash memory is unavailable or too slow. IC Role / Device Role / Timing Role: Parallel EEPROM acting as ROM replacement; JEDEC pinout ensures drop-in compatibility with existing PCB layouts. Use Value: 70 ns access time meets tight timing budgets of legacy microcontrollers; 5 V operation avoids level-shifting complexity. | Use Scenario: Storing seat position presets, mirror angles, and lighting profiles in automotive body control units subject to wide thermal cycling and EMI. IC Role / Device Role / Timing Role: Industrial-temp EEPROM interfaced directly to MCU GPIOs; page write minimizes bus occupation during user preference saves. Use Value: –40°C to +85°C rating and robust noise filtering on CE/WE inputs ensure reliable operation under vehicle electrical noise and temperature extremes. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28C256-70PU | Same 256-Kbit organization and 70 ns speed, but in 28-pin PDIP package; lacks PLCC mechanical robustness and thermal performance | Suitable for prototyping or low-volume through-hole designs; not recommended for vibration-prone or high-reliability industrial assemblies | Select only if board layout requires DIP footprint and thermal/mechanical stress is minimal |
| MX28F256J3F-70 | 32-pin PLCC, 70 ns, but requires 12 V for programming; no built-in software data protection or VCC-sense write inhibit | Used in older Intel MCS-51 systems; lacks modern reliability features like automatic page write and DATA polling | Choose only for strict legacy compatibility; AT28HC256-70JU offers superior write safety and ease of integration |
Compared with AT28C256-70PU and MX28F256J3F-70, the AT28HC256-70JU delivers enhanced system-level reliability through integrated VCC-sense, software data protection, and automatic page write-reducing firmware development effort and field failure risk without changing PCB layout.
Availability
AT28HC256-70JU is available at Aetrix Electronics and suitable for industrial PLCs, medical diagnostics equipment, legacy embedded boot systems, and automotive body control modules requiring stable component supply across multi-year production cycles.
Supply support for AT28HC256-70JU 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 is a global semiconductor company specializing in microcontrollers, analog devices, and nonvolatile memory solutions, with a focus on industrial, automotive, and communications markets.
The AT28HC256 product line delivers high-speed, low-power parallel EEPROMs designed for firmware storage, configuration retention, and calibration data logging in systems where flash memory is unsuitable or unavailable.
FAQ
What is the maximum page write size supported by the AT28HC256-70JU?
The AT28HC256-70JU supports up to 64 bytes per page write operation. This is enabled by its internal 64-byte page register, which latches address and data simultaneously-allowing the host processor to release the bus early. All bytes written in a single page cycle must reside within the same 64-byte boundary defined by address bits A6–A14. The AT28HC256-70JU enforces a 150 µs maximum interval between successive byte writes (tBLC) to maintain page integrity.
Does the AT28HC256-70JU require a 12 V supply for normal operation?
No, the AT28HC256-70JU operates from a single 5 V ±10% supply for all standard read and write functions. A 12 V ±0.5 V supply on pin A9 is required only for accessing the 64-byte device identification memory (7FC0H–7FFFH) or executing the optional chip erase mode. During regular operation-including software data protection enable/disable sequences-the AT28HC256-70JU uses only 5 V, and its internal VCC-sense circuit actively inhibits writes if VCC drops below ~3.8 V.
How does DATA polling work on the AT28HC256-70JU?
During a byte or page write cycle, reading the last written address returns the complement of the written data on I/O7 until the internal programming completes. Once valid data appears on I/O7, the write cycle is finished and the next access may begin. This mechanism allows the host to poll asynchronously without fixed delays. The AT28HC256-70JU guarantees this behavior across its full industrial temperature range and does not require external components-making it simpler to implement than timer-based or interrupt-driven methods.
Can the AT28HC256-70JU be used as a direct replacement for older EPROMs like the 27C256?
The AT28HC256-70JU is pin-compatible with the 27C256 in 32-pin PLCC packages and shares the same JEDEC byte-wide pinout, but it is not a functional drop-in replacement. Unlike UV-erasable EPROMs, the AT28HC256-70JU supports in-system electrical erasure and writing without removing the device. It also requires no 12 V programming voltage during normal writes and includes hardware write protection. While the AT28HC256-70JU simplifies design upgrades, firmware must be updated to handle DATA polling or toggle-bit status instead of fixed programming delays.
What is the endurance rating of the AT28HC256-70JU, and how is it verified?
The AT28HC256-70JU is rated for 10,000 write/erase cycles under standard industrial conditions (–40°C to +85°C, VCC = 5 V ±10%). This specification is derived from accelerated life testing per Microchip's quality standards and reflects guaranteed minimum endurance-not typical or best-case values. Endurance applies to the main 32,768 × 8 array; the 64-byte identification memory has separate characterization but is not rated for the same cycle count. The AT28HC256-70JU achieves this via internal error correction and advanced CMOS process technology.
AT28HC256-70JU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 32-LCC (J-Lead)
- Packaging:
- Tube
- Product Status:
- Active
- Programmable:
- 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:
- Surface Mount
- Supplier Device Package:
- 32-PLCC (13.97x11.43)
AT28HC256-70JU FAQ
1.How can I place an order for AT28HC256-70JU through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28HC256-70JU 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 AT28HC256-70JU reliable?
The price and inventory of AT28HC256-70JU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28HC256-70JU is usually 5 days.
3.What payment methods are accepted for AT28HC256-70JU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28HC256-70JU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28HC256-70JU?
AT28HC256-70JU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28HC256-70JU 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 AT28HC256-70JU?
For technical support, including AT28HC256-70JU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28HC256-70JU requirements.
6.How does Aetrix verify that AT28HC256-70JU is sourced from the original manufacturer or authorized distributors?
All AT28HC256-70JU 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 AT28HC256-70JU meets industry standards.
7.What is the process for return or replacement of AT28HC256-70JU?
All AT28HC256-70JU units undergo pre-shipment inspection (PSI). If there is an issue with AT28HC256-70JU, 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 AT28HC256-70JU part is unused and in its original packaging.
Return procedure for AT28HC256-70JU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT28HC256-70JU Tags
-
M24C02-WMN6TP
STMicroelectronics
-
AT24C02C-XHM-T
Microchip Technology
-
AT21CS01-STUM10-T
Microchip Technology
-
AT24C02C-SSHM-T
Microchip Technology
-
24LC01BT-I/OT
Microchip Technology
-
M24C02-FMC6TG
STMicroelectronics
-
AT24CS02-SSHM-T
Microchip Technology
-
93LC46BT-I/OT
Microchip Technology
-
AT24C04C-SSHM-T
Microchip Technology
-
24LC01BT-I/SN
Microchip Technology
-
24AA02UIDT-I/OT
Microchip Technology
-
AT24C08C-STUM-T
Microchip Technology
Tech Hub
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
