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Microchip Technology AT28HC256E-90SU
- Part No.:
- AT28HC256E-90SU
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
AT28HC256E-90SU.pdf
- Description:
- IC EEPROM 256KBIT PAR 28SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,024
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Product details
Overview
AT28HC256E-90SU from Microchip Technology is a 256-Kbit (32,768 × 8) parallel EEPROM with 90 ns read access time, single 5V ±10% supply, and industrial temperature range (–40°C to +85°C). It supports 1–64-byte page writes with ≤10 ms internal write cycle time, hardware/software data protection, and DATA Polling for write completion detection - deployed in embedded control firmware storage, industrial PLC configuration memory, and legacy ISA-bus peripheral nonvolatile storage.
For engineers reviewing the AT28HC256E-90SU datasheet, AT28HC256E-90SU pinout, AT28HC256E-90SU application, or AT28HC256E-90SU equivalent, key selection considerations include JEDEC byte-wide pin compatibility, 100,000 write endurance, 10-year data retention, 3 mA standby current, and PLCC-32/SOIC-28 package options with RoHS-compliant green packaging.
Technical Context
The AT28HC256E-90SU operates as a parallel-access EEPROM with static RAM-like read/write interface logic, requiring no external timing components. Its internal 64-byte page register enables burst loading of up to 64 bytes before initiating automatic internal programming via an on-chip control timer.
Write completion is verified via dual methods: DATA Polling (complement-to-data on I/O7) and Toggle Bit (I/O6 toggling during write). Hardware protection includes VCC sense (<3.8 V inhibits write), 5 ms power-on delay, and noise filtering on WE/CE inputs; software protection uses a 3-byte command sequence to enable/disable write lock.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8) - supports full firmware image or configuration table storage without external address multiplexing |
| Read Access Time | 90 ns max - meets timing requirements for 10 MHz ISA bus and legacy microcontroller interfaces |
| Page Write Cycle | ≤10 ms - enables efficient bulk parameter updates while minimizing system blocking time |
| Endurance | 100,000 write cycles - validated for high-frequency calibration data logging in industrial sensors |
| Data Retention | 10 years at +85°C - ensures long-term reliability in unattended equipment without battery backup |
| Supply Voltage | 5V ±10% - compatible with standard TTL/CMOS logic rails and eliminates need for dedicated voltage regulators |
| Standby Current | 3 mA max - reduces power budget impact in always-on industrial controllers |
Pinout & Package
AT28HC256E-90SU is available in 32-lead PLCC and 28-lead SOIC packages. The SOIC-28 variant is indicated by the "SU" suffix per Microchip's marking convention (DS20006428B, Section 7.1).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus supporting full 32K-word addressing; A6–A14 define page boundaries for 64-byte page writes |
| I/O0–I/O7 | Bidirectional Data Bus | True 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 for read/write; high-Z output when asserted high |
| OE | Output Enable | Active-low output control; enables data output only when CE is also low - prevents bus contention |
| WE | Write Enable | Active-low write strobe; falling edge latches address/data; initiates byte or page write sequence |
| VCC / GND | Power Supply | Single 5V supply with 3 mA standby draw; ground reference for all I/O and internal logic |
Key Features
| Feature | Design Value |
|---|---|
| JEDEC Byte-Wide Pinout | Ensures drop-in compatibility with legacy SRAM and EPROM sockets in industrial backplanes and test equipment |
| 64-Byte Page Write | Reduces host CPU overhead by allowing sequential writes within one page without repeated address setup |
| DATA Polling & Toggle Bit | Eliminates need for fixed-delay wait states - enables deterministic write completion detection in real-time systems |
| Hardware + Software Protection | Prevents corruption during brown-out, reset, or EMI events - critical for safety-critical configuration storage |
| Industrial Temp Range | Validated operation from –40°C to +85°C - suitable for deployment in motor drives, HVAC controllers, and outdoor telecom units |
Applications
| Industrial PLC Configuration Storage | Legacy ISA-Bus Peripheral Firmware |
|---|---|
Use Scenario: Storing user-defined ladder logic parameters, I/O mapping tables, and calibration coefficients in programmable logic controllers. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed via parallel bus during boot and runtime reconfiguration. Use Value: 100,000-cycle endurance supports frequent field updates; 90 ns access enables real-time parameter recall without interrupt latency penalty. | Use Scenario: Holding BIOS extension code, device initialization routines, and hardware-specific drivers in ISA-based measurement cards and data acquisition modules. IC Role / Device Role / Timing Role: Parallel boot ROM replacement with in-system programmability for field upgrades. Use Value: JEDEC pinout allows direct socket replacement of obsolete 27C256 EPROMs; software protection prevents accidental overwrite during hot-plug operations. |
| Embedded Controller Bootloader Storage | Medical Device Calibration Memory |
Use Scenario: Storing secure bootloader images and public key certificates in medical imaging subsystems and diagnostic analyzers. IC Role / Device Role / Timing Role: Secure, tamper-resistant firmware storage with hardware VCC-sense write inhibit during power transitions. Use Value: 10-year data retention guarantees certificate validity across device lifecycle; 5V-only interface simplifies power domain design. | Use Scenario: Recording sensor offset/gain coefficients, patient-specific calibration profiles, and regulatory audit logs in portable ultrasound and infusion pumps. IC Role / Device Role / Timing Role: High-reliability parameter memory with deterministic write verification via DATA Polling. Use Value: ≤10 ms page write time enables fast recalibration during service mode; 3 mA standby current extends battery life in portable units. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28HC256-90PU | Same electrical specs and timing; PLCC-32 package instead of SOIC-28 | Requires different PCB footprint and reflow profile; suited for through-hole or socketed legacy designs | Select when mechanical compatibility with existing PLCC sockets or thermal mass requirements dictate leaded package |
| MX28F256J3F | 512 Kbit capacity, 120 ns access, 3.3V/5V dual-supply support, no software protection | Higher density but slower access; lacks SDP and VCC-sense - requires external write-protection logic | Choose only if capacity expansion is primary need and system-level write control can be implemented externally |
Compared with AT28HC256E-90SU, the AT28HC256-90PU offers identical functionality in PLCC-32 for socket-based systems, while MX28F256J3F trades write protection and speed for higher density and dual-voltage flexibility - making AT28HC256E-90SU optimal for safety-critical, space-constrained industrial firmware storage where reliability and ease of integration are prioritized.
Availability
AT28HC256E-90SU is available at Aetrix Electronics and suitable for industrial PLC configuration storage, legacy ISA-bus peripheral firmware, and embedded controller bootloader storage requiring stable component supply, long-term lifecycle support, and RoHS-compliant green packaging.
Supply support for AT28HC256E-90SU 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 Inc. is a leading provider of microcontrollers, analog devices, and memory solutions, serving industrial, automotive, and consumer markets with high-reliability silicon and development tools.
The AT28HC256 product line delivers industrial-grade parallel EEPROMs optimized for legacy system upgrades, firmware storage in resource-constrained environments, and applications demanding proven 5V compatibility and robust data integrity mechanisms.
FAQ
What is the maximum write endurance specification for the AT28HC256E-90SU?
The AT28HC256E-90SU is rated for 100,000 write/erase cycles per memory location, as confirmed in the Microchip DS20006428B datasheet Section 1 (Features) and Section 4.3 (DC Characteristics). This extended endurance variant (denoted by the "E" suffix) is validated under industrial temperature conditions and supports frequent field calibration updates without premature wear-out.
Does the AT28HC256E-90SU support both byte and page write operations?
Yes, the AT28HC256E-90SU supports both byte and page write modes. A single byte write initiates an internal programming cycle, while page write allows up to 64 bytes to be loaded into the internal latch before automatic programming begins. The page write cycle time is ≤10 ms, and successive bytes must be loaded within 150 µs (tBLC) to remain in the same page, as specified in Section 6.8 of the DS20006428B datasheet.
How is write completion detected on the AT28HC256E-90SU?
Write completion on the AT28HC256E-90SU is detected using two hardware-supported methods: DATA Polling (reading I/O7 returns complement of last written data until complete, then true data) and Toggle Bit (I/O6 toggles between 0 and 1 during write, then stabilizes). Both methods are fully documented in Sections 6.14 and 6.16 of the DS20006428B datasheet and require no external components.
What package type does the "SU" suffix indicate for the AT28HC256E-90SU?
The "SU" suffix in AT28HC256E-90SU denotes the 28-lead Small Outline Integrated Circuit (SOIC) package, per Microchip's official marking convention in Section 7.1 of DS20006428B. This surface-mount package measures 17.9 mm × 7.5 mm and is RoHS-compliant, distinguishing it from the "PU" (PLCC-32) and "TU" (TSOP) variants.
Is software data protection enabled by default on the AT28HC256E-90SU?
No, software data protection (SDP) is disabled by default on the AT28HC256E-90SU. The device ships with SDP inactive and requires execution of a specific three-byte command sequence (AAh → 55h → A0h to addresses 5555h, 2AAAh, and 5555h respectively) to enable protection, as detailed in Section 6.11 of DS20006428B. Once enabled, SDP remains active across power cycles until explicitly disabled.
AT28HC256E-90SU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- 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:
- 90 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-SOIC
AT28HC256E-90SU FAQ
1.How can I place an order for AT28HC256E-90SU through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28HC256E-90SU 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-90SU reliable?
The price and inventory of AT28HC256E-90SU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28HC256E-90SU is usually 5 days.
3.What payment methods are accepted for AT28HC256E-90SU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28HC256E-90SU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28HC256E-90SU?
AT28HC256E-90SU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28HC256E-90SU 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-90SU?
For technical support, including AT28HC256E-90SU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28HC256E-90SU requirements.
6.How does Aetrix verify that AT28HC256E-90SU is sourced from the original manufacturer or authorized distributors?
All AT28HC256E-90SU 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-90SU meets industry standards.
7.What is the process for return or replacement of AT28HC256E-90SU?
All AT28HC256E-90SU units undergo pre-shipment inspection (PSI). If there is an issue with AT28HC256E-90SU, 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-90SU part is unused and in its original packaging.
Return procedure for AT28HC256E-90SU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT28HC256E-90SU Tags
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M24C02-WMN6TP
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AT24C02C-XHM-T
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AT21CS01-STUM10-T
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24LC01BT-I/OT
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M24C02-FMC6TG
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AT24CS02-SSHM-T
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93LC46BT-I/OT
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AT24C04C-SSHM-T
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24LC01BT-I/SN
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24AA02UIDT-I/OT
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AT24C08C-STUM-T
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