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Microchip Technology AT28HC256E-90SU-T
- Part No.:
- AT28HC256E-90SU-T
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
AT28HC256E-90SU-T.pdf
- Description:
- IC EEPROM 256KBIT PAR 28SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,546
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Product details
Overview
AT28HC256E-90SU-T from Microchip Technology is a 256-Kbit (32,768 × 8) parallel EEPROM with 90 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 ≤10 ms cycle time, hardware/software data protection, and DATA Polling for write completion detection. Used in embedded control systems requiring nonvolatile parameter storage with SRAM-like interface simplicity.
For engineers reviewing the AT28HC256E-90SU-T datasheet, AT28HC256E-90SU-T pinout, AT28HC256E-90SU-T application, or AT28HC256E-90SU-T equivalent, this page delivers verified electrical specs, JEDEC-compliant byte-wide pin mapping, endurance (100,000 cycles), data retention (10 years), and real-world use context for industrial firmware, calibration, and configuration memory design.
Technical Context
The AT28HC256E-90SU-T implements a CMOS-based parallel EEPROM architecture with internal 64-byte page latches and autonomous write timing. Its dual-line chip enable (CE) and output enable (OE) logic enables bus contention avoidance in shared-memory systems, while VCC sense and noise filtering prevent inadvertent writes during power transitions.
It features two end-of-write detection methods: DATA Polling on I/O7 (complement-to-data during write, true data after completion) and Toggle Bit on I/O6 (toggling until write finishes). The device includes 64 bytes of dedicated identification memory accessible via A9 = 12V and supports optional software chip erase using a 6-byte command sequence.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8), enabling full system configuration storage without external address multiplexing |
| Read Access Time | 90 ns max - meets timing requirements for 11 MHz CPU bus interfaces with no wait states |
| Page Write Cycle Time | ≤10 ms - allows burst programming of up to 64 bytes with minimal host CPU overhead |
| Endurance | 100,000 write/erase cycles - supports field-updatable calibration tables in industrial controllers |
| Data Retention | 10 years at 85°C - ensures long-term reliability in unattended equipment without battery backup |
| Supply Voltage | 5V ±10% - compatible with legacy 5V TTL/CMOS logic families and eliminates need for level shifters |
| Operating Temperature | −40°C to +85°C - qualified for deployment in industrial PLCs, motor drives, and outdoor instrumentation |
Pinout & Package
AT28HC256E-90SU-T is packaged in a 28-lead Small Outline Integrated Circuit (SOIC) with JEDEC-standard byte-wide pinout. Pin 1 is index-marked; pins are arranged for direct replacement into existing 28-pin parallel memory footprints.
| 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 | True 8-bit parallel interface; I/O7 used for DATA Polling, I/O6 for Toggle Bit status reporting |
| CE | Chip Enable | Active-low selection signal; must be low for read/write; high-Z output when CE high regardless of OE state |
| OE | Output Enable | Active-low output gate; controls data bus drive only when CE is also low - enables bus sharing |
| WE | Write Enable | Active-low write strobe; falling edge latches address/data; initiates byte or page write upon CE/WE coordination |
| VCC / GND | Power Supply | Single 5V supply with <3 mA standby current - reduces system power budget in always-on monitoring nodes |
Key Features
| Feature | Design Value |
|---|---|
| Automatic Page Write | Internal 64-byte latch and timer eliminate host-side write-loop timing management - simplifies firmware |
| DATA Polling & Toggle Bit | Dual asynchronous write-completion signaling (I/O7 complement, I/O6 toggle) enables interrupt-driven or polling-based host synchronization |
| Hardware Write Protection | VCC sense (<3.8V inhibit), 5 ms power-on delay, and noise filtering (<15 ns pulse rejection) prevent spurious writes during brown-out or EMI events |
| Software Data Protection (SDP) | User-enabled 3-byte command sequence (AA/55/A0) blocks all writes until re-enabled - secures factory calibration or security keys |
| Device Identification Memory | Dedicated 64-byte EEPROM region (7FC0H–7FFFH) accessible via A9 = 12V - stores serial numbers, revision codes, or calibration offsets |
Applications
| Industrial PLC Configuration Storage | Medical Device Calibration Memory |
|---|---|
Use Scenario: Storing I/O mapping, PID tuning parameters, and alarm thresholds in programmable logic controllers deployed in factory automation environments. IC Role / Device Role / Timing Role: Nonvolatile configuration register bank accessed via parallel bus during boot and runtime updates; 90 ns read latency aligns with 11 MHz controller bus timing. Use Value: Eliminates need for battery-backed SRAM; 100,000-cycle endurance supports frequent field recalibration; 10-year data retention ensures compliance with industrial maintenance schedules. |
Use Scenario: Holding sensor offset/gain coefficients and safety-critical operational limits in portable diagnostic equipment requiring traceable calibration history. IC Role / Device Role / Timing Role: Secure parameter vault with SDP enabled; identification memory stores unique device ID and calibration date stamped at manufacturing. Use Value: Prevents unauthorized parameter modification; 5V-only interface simplifies power design; RoHS-compliant green packaging meets medical regulatory requirements. |
| Automotive Body Control Module (BCM) | Test Equipment Setup Memory |
Use Scenario: Retaining user preferences (window position, mirror angle), fault logs, and adaptive learning values in automotive BCMs operating across extended temperature ranges. IC Role / Device Role / Timing Role: Industrial-grade EEPROM interfaced directly to microcontroller's external memory bus; −40°C to +85°C rating matches under-hood thermal profiles. Use Value: No external voltage translators needed; hardware write protection prevents corruption during ignition cycling; page write minimizes update time during vehicle reprogramming. |
Use Scenario: Preserving instrument-specific test sequences, limit thresholds, and fixture compensation data across power cycles in automated test systems. IC Role / Device Role / Timing Role: High-reliability configuration store accessed during system initialization; 90 ns access enables fast setup loading without CPU wait states. Use Value: Reduces test station boot time; 10 ms max page write supports rapid firmware patching; JEDEC pinout ensures drop-in compatibility with legacy test hardware designs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28HC256-90JU | Same die, 32-lead PLCC package; 70 ns variant available but not 90 ns in PLCC | Requires PCB footprint change; higher profile may impact board stacking height | Select when PLCC socketing or legacy board reuse is required; verify mechanical clearance |
| BR24G256FJ-3GE2 | I²C interface, 1 MHz clock, 5 ms write time; no parallel bus or page write capability | Suitable only for low-pin-count MCU designs with I²C peripherals; incompatible with SRAM-style bus protocols | Choose for space-constrained designs where serial interface suffices and bus arbitration is not needed |
Compared with AT28HC256E-90SU-T, the AT28HC256-90JU offers identical electrical behavior but demands PLCC layout changes, while BR24G256FJ-3GE2 trades parallel speed and page write flexibility for pin count reduction and simplified routing - making it viable only where bus bandwidth and host CPU overhead are secondary to footprint size.
Availability
AT28HC256E-90SU-T is available at Aetrix Electronics and suitable for industrial control systems, medical instrumentation, automotive body electronics, and automated test equipment requiring stable component supply, long-lifecycle support, and RoHS-compliant green packaging.
Supply support for AT28HC256E-90SU-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 Inc. is a leading provider of microcontrollers, analog components, and memory solutions, serving industrial, automotive, and consumer markets with vertically integrated silicon and development tools.
The AT28HC256E-90SU-T belongs to Microchip's high-speed parallel EEPROM product line, engineered for systems needing SRAM-compatible nonvolatile storage with robust write protection, extended endurance, and industrial-grade reliability.
FAQ
What is the maximum page write size supported by the AT28HC256E-90SU-T?
The AT28HC256E-90SU-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 on the first write strobe and accepts subsequent bytes within 150 µs (tBLC) of the prior byte. All bytes must reside on the same page defined by A6–A14; A0–A5 select individual byte positions within that page.
Does the AT28HC256E-90SU-T require a 12V supply for any operation?
The AT28HC256E-90SU-T operates solely from a 5V ±10% supply during normal read/write operations. A 12V ±0.5V supply is required only for accessing the 64-byte device identification memory (addresses 7FC0H–7FFFH) by raising A9 to 12V - this is an optional feature and not needed for standard memory functions.
How does hardware write protection function in the AT28HC256E-90SU-T?
Hardware write protection in the AT28HC256E-90SU-T activates automatically when VCC drops below ~3.8V, inhibiting writes during power ramp-up/down. It also incorporates a 5 ms internal power-on delay after VCC stabilization and rejects noise pulses shorter than 15 ns on WE or CE inputs - collectively preventing spurious writes in electrically noisy or unstable power environments.
Can the AT28HC256E-90SU-T be used as a direct replacement for older AT28C256 variants?
The AT28HC256E-90SU-T is pin-compatible and functionally equivalent to AT28C256 in read mode but offers faster write performance (10 ms page write vs. 20+ ms), enhanced endurance (100,000 vs. 10,000 cycles), and added features like DATA Polling and software data protection. Electrical compatibility is maintained, but firmware should verify write timing and protection enable sequences.
What is the purpose of the "E" suffix in AT28HC256E-90SU-T?
The "E" in AT28HC256E-90SU-T denotes extended endurance: 100,000 write/erase cycles versus the base AT28HC256's 10,000 cycles. This is achieved through Microchip's advanced CMOS process and internal error correction, making AT28HC256E-90SU-T suitable for applications requiring frequent field updates such as calibration or configuration logging.
AT28HC256E-90SU-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-SOIC (0.295", 7.50mm Width)
- 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:
- 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-T FAQ
1.How can I place an order for AT28HC256E-90SU-T through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28HC256E-90SU-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-90SU-T reliable?
The price and inventory of AT28HC256E-90SU-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-90SU-T is usually 5 days.
3.What payment methods are accepted for AT28HC256E-90SU-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28HC256E-90SU-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28HC256E-90SU-T?
AT28HC256E-90SU-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28HC256E-90SU-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-90SU-T?
For technical support, including AT28HC256E-90SU-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28HC256E-90SU-T requirements.
6.How does Aetrix verify that AT28HC256E-90SU-T is sourced from the original manufacturer or authorized distributors?
All AT28HC256E-90SU-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-90SU-T meets industry standards.
7.What is the process for return or replacement of AT28HC256E-90SU-T?
All AT28HC256E-90SU-T units undergo pre-shipment inspection (PSI). If there is an issue with AT28HC256E-90SU-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-90SU-T part is unused and in its original packaging.
Return procedure for AT28HC256E-90SU-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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