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Microchip Technology AT28HC256F-90SU-T
- Part No.:
- AT28HC256F-90SU-T
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
AT28HC256F-90SU-T.pdf
- Description:
- IC EEPROM 256KBIT PAR 28SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,000
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Product details
Overview
AT28HC256F-90SU-T from Microchip Technology is a 256-Kbit (32,768 × 8) parallel EEPROM with 90 ns read access time, 3 ms fast page write cycle, single 5V ±10% supply, and industrial temperature range (–40°C to +85°C). It features hardware/software data protection, DATA polling, and JEDEC-standard byte-wide pinout for embedded system configuration storage.
For engineers reviewing the AT28HC256F-90SU-T datasheet, AT28HC256F-90SU-T pinout, AT28HC256F-90SU-T application, or AT28HC256F-90SU-T equivalent, this device serves as a drop-in replacement for legacy parallel EEPROMs in firmware boot loaders, calibration data retention, and industrial control parameter storage where reliable nonvolatile memory with deterministic timing is required.
Technical Context
The AT28HC256F-90SU-T implements a CMOS-based EEPROM architecture with internal 64-byte page latches and an autonomous control timer for self-timed write operations. Its dual-line chip enable (CE) and output enable (OE) logic enables bus contention avoidance in shared-memory systems.
It supports three distinct write modes: byte write, page write (1–64 bytes within same A6–A14 page), and optional software chip erase. End-of-write detection is implemented via DATA Polling on I/O7 and Toggle Bit on I/O6 - both usable at any point during the write cycle without external timing constraints.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory size | 256 Kbit (32,768 × 8) - provides sufficient space for firmware headers, sensor calibration tables, or configuration registers in resource-constrained controllers. |
| Read access time | 90 ns - ensures compatibility with 10 MHz+ microcontroller buses without wait states in standard read cycles. |
| Page write time | 3 ms maximum - reduces firmware update latency compared to standard 10 ms variants, critical for field-upgradable industrial modules. |
| Supply voltage | 5 V ±10% - operates directly from legacy 5 V rails without LDO regulation, simplifying power design. |
| Endurance | 10,000 write/erase cycles - validated for applications requiring infrequent but mission-critical parameter updates (e.g., energy meter tariff settings). |
| Data retention | 10 years at +85°C - guarantees long-term integrity of stored calibration coefficients or security keys in unattended equipment. |
| Operating temperature | –40°C to +85°C - certified for deployment in industrial PLCs, motor drives, and outdoor telemetry units. |
| Package | 28-Lead SOIC (SOIC-28) - surface-mount compatible with standard reflow profiles and automated assembly lines. |
Pinout & Package
AT28HC256F-90SU-T is supplied in a 28-Lead Small Outline Integrated Circuit (SOIC-28) package with JEDEC-standard byte-wide pinout. Pin 1 is located at the top-left corner with a beveled edge marker; pins are numbered counter-clockwise.
| 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 end-of-write detection. |
| CE | Chip Enable | Active-low global enable; must be low for read/write access; high-Z state when deasserted prevents bus contention. |
| OE | Output Enable | Active-low output gate; allows independent control of data bus drivers during reads, enabling multiplexed memory sharing. |
| WE | Write Enable | Active-low write strobe; falling edge latches address/data; rising edge initiates internal programming sequence. |
| VCC | Power supply | +5 V ±10% main supply; powers core logic and memory array; includes internal VCC sense for write inhibition below 3.8 V. |
| GND | Ground reference | Signal and power return path; decoupling capacitor placement near Pin 14 is required for stable 90 ns read timing. |
Key Features
| Feature | Design Value |
|---|---|
| Fast 3 ms page write | Reduces firmware update time by 70% vs. 10 ms variants, enabling faster factory programming and field calibration cycles. |
| DATA Polling on I/O7 | Allows real-time, asynchronous detection of write completion without fixed delays or external timers - eliminates polling overhead in host firmware. |
| Hardware write protection | VCC sense + 5 ms power-on delay + noise filtering (<15 ns pulses rejected) prevent spurious writes during brown-out or EMI events. |
| Software data protection (SDP) | Three-step command sequence (AAh/55h/A0h) enables/disables write lock per device; retains state across power cycles. |
| 64-byte identification area | Accessible via A9 = 12 V, addresses 7FC0h–7FFFh - stores unique serial numbers, manufacturing trace codes, or calibration checksums. |
Applications
| Industrial PLC Configuration Storage | Firmware Boot Loader Memory |
|---|---|
|
Use Scenario: Storing I/O mapping tables, PID tuning parameters, and alarm thresholds in programmable logic controllers deployed in factory automation. IC Role / Device Role / Timing Role: Nonvolatile configuration register bank accessed during cold start and runtime parameter updates; 90 ns read speed supports deterministic scan-cycle timing. Use Value: Ensures parameter persistence after power loss and enables field recalibration without firmware reflashing - reducing maintenance downtime. |
Use Scenario: Holding bootloader code and secure boot signatures in microcontroller-based edge gateways requiring verified firmware startup. IC Role / Device Role / Timing Role: Parallel-mapped boot ROM accessed at reset; 3 ms page write allows rapid signature verification and secure key loading during boot sequence. Use Value: Eliminates dependency on internal flash endurance limits; separates trusted boot code from application flash for improved security isolation. |
| Energy Meter Calibration Data | Medical Device Setup Profiles |
|
Use Scenario: Retaining meter-specific gain/offset coefficients and tariff schedules in ANSI C12.20-compliant electricity meters operating at –25°C to +70°C ambient. IC Role / Device Role / Timing Role: Calibration coefficient repository with 10-year data retention guarantee; accessed only during metrology initialization phase. Use Value: Meets IEC 62053 accuracy requirements over product lifetime without periodic recalibration - lowering total cost of ownership. |
Use Scenario: Storing patient-specific therapy parameters (e.g., infusion rates, pressure limits) in Class IIa infusion pumps requiring FDA 21 CFR Part 11 compliance. IC Role / Device Role / Timing Role: Secure, write-protected parameter vault; SDP-enabled to prevent accidental overwrite during clinical use. Use Value: Supports audit trail generation via 64-byte ID area; satisfies traceability requirements for device configuration history. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28HC256-90SU | Same 90 ns access, 10 ms page write, no 'F' suffix - lacks 3 ms fast write capability. | Suitable for non-time-critical configuration storage where update latency is not constrained. | Select when firmware update speed is secondary to cost optimization and legacy design continuity. |
| ST M28W256FCT | 256 Kbit, 100 ns read, 5 ms page write, 3.3 V/5 V dual supply - different voltage flexibility and timing envelope. | Used in mixed-voltage systems where 3.3 V logic coexists with 5 V peripherals. | Choose when board-level voltage scaling requires dual-supply compatibility and 3.3 V I/O tolerance. |
Compared with AT28HC256-90SU, the AT28HC256F-90SU-T delivers 70% faster page writes for time-sensitive field updates; versus ST M28W256FCT, it offers tighter 90 ns read timing and simpler 5 V-only power design but lacks 3.3 V interface support.
Availability
AT28HC256F-90SU-T is available at Aetrix Electronics and suitable for industrial PLC configuration storage, firmware boot loader memory, and energy meter calibration data retention requiring stable component supply across multi-year production cycles.
Supply support for AT28HC256F-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 is a global semiconductor company specializing in microcontrollers, analog devices, and nonvolatile memory solutions, with a focus on industrial, automotive, and aerospace reliability standards.
The AT28HC256 product line delivers high-speed parallel EEPROMs optimized for deterministic timing, robust data retention, and hardware/software write protection in mission-critical embedded systems.
FAQ
What is the guaranteed write endurance of the AT28HC256F-90SU-T?
The AT28HC256F-90SU-T is rated for 10,000 write/erase cycles under industrial conditions. This endurance level is validated per Microchip's DS20006428B specification and applies to both byte and page write operations across the full temperature range (–40°C to +85°C). The device does not support extended 100,000-cycle variants - that rating applies only to the 'E' suffix version (e.g., AT28HC256E-90SU-T).
Does the AT28HC256F-90SU-T support 3.3 V operation?
No, the AT28HC256F-90SU-T requires a single 5 V ±10% supply (4.5 V to 5.5 V) and is not 3.3 V tolerant. Its input thresholds (VIL ≤ 0.8 V, VIH ≥ 2.0 V) and output drive levels (VOL ≤ 0.45 V, VOH ≥ 2.4 V) are specified for 5 V CMOS/TTL compatibility. Interfacing with 3.3 V microcontrollers requires level-shifting circuitry or voltage translation buffers.
How is the 3 ms page write time achieved in the AT28HC256F-90SU-T?
The AT28HC256F-90SU-T achieves 3 ms maximum page write time through an enhanced internal control timer and optimized charge-pump circuitry, as confirmed in Table 6-4 of DS20006428B. This 'F' suffix variant uses the same 64-byte page latch architecture as standard AT28HC256 parts but with accelerated programming voltage generation - distinct from the 10 ms timing of non-F versions.
Can the AT28HC256F-90SU-T be used as a direct replacement for AT28HC256-90SU?
Yes, the AT28HC256F-90SU-T is pin-compatible and functionally identical to AT28HC256-90SU in all modes except page write timing. Both share identical pinout, DC/AC characteristics, software protection commands, and JEDEC-compliant packaging. The only functional difference is the reduced 3 ms (vs. 10 ms) page write time - which improves performance without requiring PCB or firmware changes.
What is the purpose of the 64-byte identification area in the AT28HC256F-90SU-T?
The 64-byte identification area (addresses 7FC0h–7FFFh) in the AT28HC256F-90SU-T is a dedicated EEPROM segment accessible only when A9 is raised to 12 V ±0.5 V. It is intended for storing unique device identifiers, manufacturing lot codes, calibration checksums, or security keys - physically isolated from main memory to prevent accidental overwrite during normal operation.
AT28HC256F-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:
- 3ms
- 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
AT28HC256F-90SU-T FAQ
1.How can I place an order for AT28HC256F-90SU-T through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28HC256F-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 AT28HC256F-90SU-T reliable?
The price and inventory of AT28HC256F-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 AT28HC256F-90SU-T is usually 5 days.
3.What payment methods are accepted for AT28HC256F-90SU-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28HC256F-90SU-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28HC256F-90SU-T?
AT28HC256F-90SU-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28HC256F-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 AT28HC256F-90SU-T?
For technical support, including AT28HC256F-90SU-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28HC256F-90SU-T requirements.
6.How does Aetrix verify that AT28HC256F-90SU-T is sourced from the original manufacturer or authorized distributors?
All AT28HC256F-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 AT28HC256F-90SU-T meets industry standards.
7.What is the process for return or replacement of AT28HC256F-90SU-T?
All AT28HC256F-90SU-T units undergo pre-shipment inspection (PSI). If there is an issue with AT28HC256F-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 AT28HC256F-90SU-T part is unused and in its original packaging.
Return procedure for AT28HC256F-90SU-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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