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Microchip Technology AT28HC256E-70JU-T

Name: AT28HC256E-70JU-T
Brand: Microchip Technology
SKU: AT28HC256E-70JU-T
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: AT28HC256E-70JU-T

Manufacturer:: Microchip Technology

Category:: Memory

Package:: 32-LCC (J-Lead)

Datasheet:: AT28HC256E-70JU-T.pdf

Description:: IC EEPROM 256KBIT PAR 32PLCC

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Product details

Overview

AT28HC256E-70JU-T from Microchip Technology is a 256-Kbit (32,768 × 8) parallel EEPROM with 70 ns read access time, single 5V ±10% supply operation, and industrial temperature range (–40°C to +85°C). It supports automatic 1–64-byte page writes with internal latching and data polling for write completion detection, used in embedded system configuration storage and firmware parameter retention.

For engineers reviewing the AT28HC256E-70JU-T datasheet, AT28HC256E-70JU-T pinout, AT28HC256E-70JU-T application, or AT28HC256E-70JU-T equivalent, this page delivers verified electrical specs, JEDEC-compliant byte-wide interface details, endurance (100,000 cycles), data retention (10 years), and hardware/software write protection implementation guidance.

Technical Context

The AT28HC256E-70JU-T implements a CMOS-based parallel EEPROM architecture with integrated address/data latches for page write operations and dual-line chip enable (CE)/output enable (OE) control to prevent bus contention. Its internal control timer manages autonomous 3 ms or 10 ms write cycles depending on variant configuration.

It features DATA Polling (I/O7 complement toggle) and Toggle Bit (I/O6 oscillation) mechanisms for real-time write status monitoring, alongside VCC sense and noise filtering to inhibit spurious writes during power transitions or EMI events.

Key Specifications

Parameter	Value and Actual Design Meaning
Memory Size	256 Kbit (32,768 × 8) - provides nonvolatile storage for boot code, calibration tables, or device configuration in microcontroller-based systems.
Read Access Time	70 ns - enables direct replacement of SRAM in legacy 8-bit bus interfaces without timing redesign.
Page Write Cycle	3 ms max (E-grade) - reduces firmware update latency versus byte-by-byte programming; supports up to 64 bytes per cycle.
Endurance	100,000 write/erase cycles - validated for applications requiring frequent field-updatable parameters (e.g., energy meter tariff tables).
Data Retention	10 years at +85°C - ensures long-term reliability in industrial control panels and automotive body modules.
Supply Voltage	5V ±10% - compatible with standard TTL/CMOS logic rails; eliminates need for auxiliary voltage regulators.
Operating Temperature	–40°C to +85°C - certified for deployment in uncontrolled environments such as factory automation I/O modules.

Pinout & Package

AT28HC256E-70JU-T is packaged in a 32-lead PLCC (Plastic Leaded Chip Carrier) with JEDEC-standard byte-wide pinout. Pin 1 and Pin 17 are designated "Don't Connect" (DC); Pins 12 and 26 are No Connect (NC). The package is RoHS-compliant and green-marked.

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 page 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 during write cycles.
CE	Chip Enable	Active-low selection signal; must be low with OE low and WE high for read access; initiates write when pulsed low with OE high.
OE	Output Enable	Active-low output control; places I/O pins in high-impedance state when high, preventing bus contention in shared-memory systems.
WE	Write Enable	Active-low write strobe; falling edge latches address/data; combined with CE and OE logic to define operating mode per Table 6-1.
VCC / GND	Power Supply	Single 5V supply with <3 mA standby current; ground reference for all digital and analog functions including VCC-sense write inhibition.

Key Features

Feature	Design Value
Hardware Write Protection	VCC sense (inhibit below 3.8V), 5 ms power-on delay, and noise filtering (<15 ns pulse rejection) prevent accidental writes during brown-out or EMI events.
Software Data Protection (SDP)	Three-step command sequence (AAh/55h/A0h to 5555h/2AAAh/5555h) enables/disables write lock; persists across power cycles and protects entire memory array.
Page Write Operation	Internal 64-byte latch allows burst loading of configuration data; each byte must be loaded within 150 µs of prior byte to remain in same page write cycle.
Write Completion Detection	DATA Polling (I/O7 complement) and Toggle Bit (I/O6 oscillation) provide software-controllable, real-time feedback without external hardware timers.
Device Identification Area	64-byte reserved EEPROM region (7FC0h–7FFFh) accessible via 12V on A9; used for serialization, calibration data, or manufacturing traceability.

Applications

Industrial PLC Configuration Storage	Medical Device Calibration Parameter Retention
Use Scenario: Storing I/O mapping, PID tuning constants, and alarm thresholds in programmable logic controllers deployed in harsh factory environments. IC Role / Device Role / Timing Role: Nonvolatile configuration register accessed via 8-bit parallel bus during power-up initialization and runtime updates. Use Value: 100,000-cycle endurance and 10-year data retention ensure reliable operation over 15+ year equipment lifecycles without battery backup.	Use Scenario: Holding patient-specific calibration coefficients and regulatory compliance logs in portable diagnostic instruments requiring FDA 21 CFR Part 11 audit trails. IC Role / Device Role / Timing Role: Secure, write-protected memory segment storing tamper-evident calibration data with SDP-enabled write locking. Use Value: Software data protection prevents unauthorized modification; 70 ns read speed supports real-time sensor offset correction during measurement cycles.
Automotive Body Control Module Settings	Telecom Equipment Bootloader Parameter Storage
Use Scenario: Retaining seat/mirror position presets, lighting profiles, and CAN node configuration in automotive BCMs subjected to thermal cycling and vibration. IC Role / Device Role / Timing Role: Industrial-grade EEPROM interfaced directly to MCU's external memory bus for fast read/write during vehicle power-up and user input events. Use Value: –40°C to +85°C operation and 5V tolerance ensure compatibility with automotive 12V supply regulation schemes; no external level-shifting required.	Use Scenario: Storing bootloader version, secure boot keys, and network interface MAC addresses in carrier-grade routers and base station controllers. IC Role / Device Role / Timing Role: Trusted nonvolatile memory holding immutable boot parameters; accessed during cold start before OS loads. Use Value: Hardware VCC-sense write inhibition prevents corruption during brown-out conditions common in telecom power systems; JEDEC pinout simplifies PCB layout reuse.

Industrial PLC Configuration Storage

Medical Device Calibration Parameter Retention

Use Scenario: Storing I/O mapping, PID tuning constants, and alarm thresholds in programmable logic controllers deployed in harsh factory environments.

IC Role / Device Role / Timing Role: Nonvolatile configuration register accessed via 8-bit parallel bus during power-up initialization and runtime updates.

Use Value: 100,000-cycle endurance and 10-year data retention ensure reliable operation over 15+ year equipment lifecycles without battery backup.

Use Scenario: Holding patient-specific calibration coefficients and regulatory compliance logs in portable diagnostic instruments requiring FDA 21 CFR Part 11 audit trails.

IC Role / Device Role / Timing Role: Secure, write-protected memory segment storing tamper-evident calibration data with SDP-enabled write locking.

Use Value: Software data protection prevents unauthorized modification; 70 ns read speed supports real-time sensor offset correction during measurement cycles.

Automotive Body Control Module Settings

Telecom Equipment Bootloader Parameter Storage

Use Scenario: Retaining seat/mirror position presets, lighting profiles, and CAN node configuration in automotive BCMs subjected to thermal cycling and vibration.

IC Role / Device Role / Timing Role: Industrial-grade EEPROM interfaced directly to MCU's external memory bus for fast read/write during vehicle power-up and user input events.

Use Value: –40°C to +85°C operation and 5V tolerance ensure compatibility with automotive 12V supply regulation schemes; no external level-shifting required.

Use Scenario: Storing bootloader version, secure boot keys, and network interface MAC addresses in carrier-grade routers and base station controllers.

IC Role / Device Role / Timing Role: Trusted nonvolatile memory holding immutable boot parameters; accessed during cold start before OS loads.

Use Value: Hardware VCC-sense write inhibition prevents corruption during brown-out conditions common in telecom power systems; JEDEC pinout simplifies PCB layout reuse.

Equivalent & Alternatives

The following parts are listed as comparable options for similar parallel EEPROM applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
AT28HC256-70PU	28-pin PDIP package; identical electrical specs but through-hole mounting and no green/RoHS marking.	Suitable for prototyping or legacy through-hole designs; lacks PLCC's thermal performance and reflow compatibility.	Select for hand-soldered evaluation or repair scenarios where surface-mount assembly is unavailable.
ST M27C256B-12F1	120 ns access time; 5V-only operation; 10,000-cycle endurance; no software data protection or page write acceleration.	Lower performance and reliability; intended for cost-sensitive, low-update-frequency applications like simple display menu storage.	Choose only if 70 ns timing and 100k-cycle endurance are not required; verify absence of SDP does not compromise system security.

Compared with AT28HC256E-70JU-T, the AT28HC256-70PU offers identical functionality in a through-hole package for manual assembly, while the ST M27C256B-12F1 trades speed, endurance, and advanced protection for lower unit cost-making it viable only in static, non-critical storage roles.

Availability

AT28HC256E-70JU-T is available at Aetrix Electronics and suitable for industrial PLC configuration storage, medical device calibration parameter retention, and automotive body control module settings requiring stable component supply across extended production lifecycles.

Supply support for AT28HC256E-70JU-T 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-reliability parallel EEPROMs optimized for legacy 8-bit bus systems requiring fast, secure, and long-life nonvolatile storage without battery backup.

FAQ

What is the maximum page write size supported by the AT28HC256E-70JU-T?

The AT28HC256E-70JU-T supports up to 64 bytes per page write operation. This is enabled by its internal 64-byte page register, which latches address and data automatically upon initiation of a write cycle. Each successive byte must be loaded within 150 µs of the previous one to remain within the same page write window; exceeding this interval triggers internal programming. The AT28HC256E-70JU-T uses A6–A14 to define page boundaries, ensuring only bytes within the same 64-byte aligned block are written.

Does the AT28HC256E-70JU-T require external high-voltage circuitry for write operations?

No, the AT28HC256E-70JU-T performs all write and erase operations using only a single 5V ±10% supply-no external 12V or higher voltage is needed for standard byte or page writes. High-voltage (12V ±0.5V on A9) is required exclusively for accessing the 64-byte device identification area or executing optional chip erase, both of which are infrequent operations. The AT28HC256E-70JU-T integrates VCC-sense circuitry to inhibit writes below 3.8V, eliminating risk of partial writes during power ramp-up.

How does software data protection (SDP) function on the AT28HC256E-70JU-T?

Software data protection (SDP) on the AT28HC256E-70JU-T is activated by writing a three-byte command sequence (AAh to 5555h, 55h to 2AAAh, A0h to 5555h) to enable write locking, or an alternate five-byte sequence to disable it. Once enabled, all subsequent writes require repeating the enable sequence before data-ensuring accidental overwrites are blocked. The AT28HC256E-70JU-T retains SDP state across power cycles, and the feature is shipped disabled. SDP applies to the entire memory array, including the identification area.

Can the AT28HC256E-70JU-T be used as a drop-in replacement for standard SRAM in existing designs?

Yes, the AT28HC256E-70JU-T is designed for SRAM-like read access: CE and OE low with WE high asserts valid data on I/O0–I/O7 within 70 ns, matching typical fast SRAM timing. Its JEDEC-approved byte-wide pinout ensures mechanical and logical compatibility with many 28-pin and 32-pin SRAM footprints. However, write cycles require explicit WE/CE control and status polling-unlike SRAM-so firmware must implement DATA Polling or Toggle Bit checking before initiating new accesses. The AT28HC256E-70JU-T does not auto-acknowledge writes.

What is the significance of the 'E' suffix in AT28HC256E-70JU-T?

The 'E' in AT28HC256E-70JU-T denotes the extended endurance grade, specifying 100,000 write/erase cycles-ten times the 10,000-cycle rating of standard-grade variants (e.g., AT28HC256-70JU-T). This is achieved through Microchip's advanced CMOS process and internal error correction. The 'E' grade is explicitly marked on the device top-side per Microchip's packaging specification and is validated across the full industrial temperature range. The AT28HC256E-70JU-T maintains identical timing, voltage, and interface behavior as non-E variants, differing only in endurance and data retention under stress.

AT28HC256E-70JU-T Specifications

Product attributes: Attribute value

Manufacturer:: Microchip Technology

Series:: -

Package/Case:: 32-LCC (J-Lead)

Packaging:: Tape & Reel (TR)

Product Status:: Active

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:: Surface Mount

Supplier Device Package:: 32-PLCC (11.43x13.97)

AT28HC256E-70JU-T FAQ

1.How can I place an order for AT28HC256E-70JU-T through Aetrix?

Please submit a Request for Quotation (RFQ) for AT28HC256E-70JU-T 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 AT28HC256E-70JU-T reliable?

The price and inventory of AT28HC256E-70JU-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28HC256E-70JU-T is usually 5 days.

3.What payment methods are accepted for AT28HC256E-70JU-T?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28HC256E-70JU-T transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for AT28HC256E-70JU-T?

AT28HC256E-70JU-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your AT28HC256E-70JU-T 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 AT28HC256E-70JU-T?

For technical support, including AT28HC256E-70JU-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28HC256E-70JU-T requirements.

6.How does Aetrix verify that AT28HC256E-70JU-T is sourced from the original manufacturer or authorized distributors?

All AT28HC256E-70JU-T 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 AT28HC256E-70JU-T meets industry standards.

7.What is the process for return or replacement of AT28HC256E-70JU-T?

All AT28HC256E-70JU-T units undergo pre-shipment inspection (PSI). If there is an issue with AT28HC256E-70JU-T, 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 AT28HC256E-70JU-T part is unused and in its original packaging.

Return procedure for AT28HC256E-70JU-T:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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