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Microchip Technology AT25256W-10SI
- Part No.:
- AT25256W-10SI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
AT25256W-10SI.pdf
- Description:
- IC EEPROM 256KBIT SPI 3MHZ 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,000
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Product details
Overview
AT25256W-10SI from Atmel (now Microchip Technology) is a 256 Kbit SPI serial EEPROM organized as 32,768 × 8-bit memory array, operating over 2.7V–5.5V supply range, supporting 3 MHz clock rate and 64-byte page write, used for nonvolatile configuration storage in industrial control modules, automotive body electronics, and embedded system boot loaders.
For engineers reviewing the AT25256W-10SI datasheet, AT25256W-10SI pinout, AT25256W-10SI application, or AT25256W-10SI equivalent, key selection criteria include industrial temperature range (−40°C to +85°C), hardware/software write protection via WP/HOLD pins, block-level write protection (1/4, 1/2, or full array), self-timed 5 ms typical write cycle, and EIAJ SOIC-8 package compatibility.
Technical Context
The AT25256W-10SI implements a synchronous SPI slave interface compliant with Modes 0 (CPOL=0, CPHA=0) and 3 (CPOL=1, CPHA=1), using separate SI (input) and SO (output) lines with MSB-first data framing. Chip select (CS) enables device access, while HOLD suspends ongoing serial transfers without resetting sequence state.
It features a nonvolatile status register with BP0/BP1 bits enabling configurable block write protection, WPEN bit controlling hardware write protect pin functionality, and RDY/WEN flags indicating internal write progress and write-enable latch status - all accessible via RDSR/WRSR instructions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Density | 262,144 bits (32,768 × 8), sufficient for firmware parameter tables or calibration data in resource-constrained systems |
| Supply Voltage Range | 2.7V to 5.5V - supports mixed-voltage designs including 3.3V microcontrollers and legacy 5V peripherals |
| Max Clock Frequency | 3 MHz - enables fast configuration reads during system boot without requiring high-speed MCU peripherals |
| Write Cycle Time | 5 ms typical - defines minimum interval between successive write commands; no external erase needed |
| Endurance | 100,000 write cycles - ensures reliable operation over product lifetime in field-updatable applications |
| Data Retention | >200 years at 25°C - guarantees long-term integrity of stored calibration or security keys |
| Operating Temperature | −40°C to +85°C - qualified for industrial and automotive under-hood environments |
Pinout & Package
AT25256W-10SI is housed in an 8-pin EIAJ SOIC (Small Outline Integrated Circuit) package, 0.200" wide, with standard gull-wing lead form and JEDEC-compliant footprint. Pin 1 is marked by a notch or dot; leads are tin-lead plated per industry standards.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 CS | Chip Select Input | Active-low enable signal; must be low to accept SPI commands; high-Z SO when CS high |
| 2 SO | Serial Data Output | Tri-state output delivering read data or status bits; high-impedance when CS high or during HOLD |
| 3 WP | Write Protect Input | Hardware lock: when WP = low and WPEN = 1, blocks writes to status register and protected memory blocks |
| 4 GND | Ground Reference | Primary return path for VCC and I/O signals; requires low-impedance PCB connection to minimize noise |
| 5 VCC | Power Supply | 2.7V–5.5V input; decoupling capacitor (0.1 µF) recommended within 10 mm of pin |
| 6 HOLD | Serial Communication Suspend | Pauses ongoing SPI transfer when pulled low during SCK low; resumes on rising edge while SCK low |
| 7 SCK | Serial Clock Input | Synchronous timing reference from master; max 3 MHz; edge-triggered sampling |
| 8 SI | Serial Data Input | Receives op-codes, addresses, and write data; sampled on SCK rising edge in Mode 0 |
Key Features
| Feature | Design Value |
|---|---|
| SPI Mode 0 & 3 Support | Interoperates with diverse microcontrollers including AVR, PIC, ARM Cortex-M, and legacy 8051 derivatives without protocol translation |
| 64-byte Page Write | Reduces write latency vs. byte-by-byte programming; enables efficient bulk updates of configuration sectors |
| Block Write Protection | Configurable via status register to lock top 1/4 (6000–7FFFh), top 1/2 (4000–7FFFh), or entire array (0000–7FFFh) |
| Hardware + Software Protection | WP pin provides physical lockout; WREN/WRDI instructions allow runtime enable/disable of write capability independent of WP state |
| Industrial Temperature Grade | Validated operation from −40°C to +85°C ensures reliability in factory automation, power meters, and vehicle ECUs |
Applications
| Industrial PLC Configuration Storage | Automotive Body Control Module (BCM) |
|---|---|
Use Scenario: Storing I/O mapping, calibration offsets, and fault history logs in programmable logic controllers deployed in harsh factory environments. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed via SPI during startup and runtime diagnostics; operates at 3 MHz for sub-millisecond read response. Use Value: Enables field-reprogrammable logic without requiring flash reprogramming tools; 100K endurance supports frequent recalibration cycles. |
Use Scenario: Holding door lock settings, mirror position presets, and lighting profiles in automotive BCMs subject to extended thermal cycling. IC Role / Device Role / Timing Role: SPI EEPROM providing persistent user preferences and safety-critical configuration data; WP pin hardwired to prevent corruption during power transients. Use Value: >200-year data retention ensures settings survive vehicle lifetime; −40°C to +85°C rating matches under-dash operating conditions. |
| Medical Device Calibration Memory | Network Equipment Bootloader Parameters |
Use Scenario: Storing sensor gain/offset coefficients and regulatory compliance flags in portable diagnostic instruments requiring traceable calibration records. IC Role / Device Role / Timing Role: Secure, tamper-resistant memory accessed only during calibration mode; block protection prevents accidental overwrite of certified parameters. Use Value: Hardware write protection (WP + WPEN) meets IEC 62304 software safety requirements for Class B medical devices. |
Use Scenario: Storing MAC address, firmware version, and network interface configuration in enterprise switches and routers during cold boot initialization. IC Role / Device Role / Timing Role: Fast-read SPI EEPROM supplying critical boot parameters before main processor initializes DRAM or NAND flash. Use Value: 3 MHz interface allows complete parameter load in <100 µs; 8-pin SOIC footprint minimizes board space in dense switch fabric layouts. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| M95256-WDW6TP | STMicroelectronics 256 Kbit SPI EEPROM; same 2.7–5.5V range, 20 MHz max clock, but uses different status register layout and lacks HOLD pin | Higher speed but no suspend capability; suitable where fast sequential reads dominate over multi-master arbitration | Select when system requires faster throughput and can manage timing without HOLD suspension |
| BR25V256FJ-WE2 | Rohm 256 Kbit SPI EEPROM; 1.7–5.5V range, 10 MHz max clock, built-in error correction (ECC), and enhanced ESD (6 kV HBM) | Broader voltage support and ECC improve robustness in battery-powered or noisy industrial settings | Select when operating below 2.7V or requiring higher immunity to bit errors in mission-critical logging |
Compared with M95256-WDW6TP and BR25V256FJ-WE2, AT25256W-10SI offers unique HOLD functionality for interrupt-safe SPI communication and proven industrial qualification - making it preferred for deterministic real-time systems where bus arbitration and thermal stability are prioritized over raw speed or ultra-low-voltage operation.
Availability
AT25256W-10SI is available at Aetrix Electronics and suitable for industrial control systems, automotive body electronics, and medical device calibration storage requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for AT25256W-10SI 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
Atmel Corporation, now part of Microchip Technology, is a semiconductor manufacturer specializing in microcontrollers, nonvolatile memory, and secure authentication ICs for industrial, automotive, and consumer markets.
The AT25xxx family was designed specifically for SPI-based embedded systems needing reliable, low-power, pin-efficient nonvolatile storage - emphasizing ease of integration, robust write protection, and extended temperature operation.
FAQ
What is the maximum clock frequency supported by the AT25256W-10SI?
The AT25256W-10SI supports a maximum SCK clock frequency of 3 MHz across its full 2.7V–5.5V supply range and −40°C to +85°C operating temperature. This value is specified in the AC Characteristics table under fSCK for VCC = 2.7–5.5V, and applies to both read and write operations. Exceeding this limit may cause data corruption or command rejection.
Does the AT25256W-10SI require an external erase cycle before writing?
No, the AT25256W-10SI does not require a separate erase cycle. All write operations - whether byte or page - are self-timed and automatically erase and program the target location internally. The device powers up in write-disabled state, so each write sequence must begin with a WREN instruction followed by WRITE or WRSR, then completion confirmed via RDSR polling.
How does the HOLD pin function during an active SPI transaction?
The HOLD pin on the AT25256W-10SI suspends serial communication when driven low while SCK is low, preserving the current address and instruction state. It does not reset the serial sequence. To resume, bring HOLD high while SCK remains low - the master may continue clocking from the exact bit position where it paused. Inputs on SI are ignored during HOLD, and SO enters high-impedance state.
Can the AT25256W-10SI be used in a 1.8V system?
No, the AT25256W-10SI is rated for 2.7V–5.5V operation only. For 1.8V systems, Atmel offers the AT25256W-10SI-1.8 variant (ordering code AT25256W-10SI-1.8), which is electrically and functionally identical except for its 1.8V–3.6V supply range. Using the -10SI part outside its specified voltage range risks functional failure or reduced reliability.
What memory organization does the AT25256W-10SI use?
The AT25256W-10SI organizes its 262,144 bits as 32,768 words of 8 bits each (32,768 × 8). Addressing uses 15-bit addressing (A14–A0), with A15 unused. The memory map is linear and contiguous, supporting sequential reads that auto-increment the address counter - allowing full memory dump in one continuous READ cycle with rollover from highest to lowest address.
AT25256W-10SI Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Type:
- Non-Volatile
- Memory Format:
- EEPROM
- Technology:
- EEPROM
- Memory Size:
- 256Kbit
- Memory Organization:
- 32K x 8
- Memory Interface:
- SPI
- Clock Frequency:
- 3 MHz
- Write Cycle Time - Word, Page:
- 5ms
- Access Time:
- -
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
AT25256W-10SI FAQ
1.How can I place an order for AT25256W-10SI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT25256W-10SI 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 AT25256W-10SI reliable?
The price and inventory of AT25256W-10SI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT25256W-10SI is usually 5 days.
3.What payment methods are accepted for AT25256W-10SI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT25256W-10SI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT25256W-10SI?
AT25256W-10SI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT25256W-10SI 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 AT25256W-10SI?
For technical support, including AT25256W-10SI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT25256W-10SI requirements.
6.How does Aetrix verify that AT25256W-10SI is sourced from the original manufacturer or authorized distributors?
All AT25256W-10SI 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 AT25256W-10SI meets industry standards.
7.What is the process for return or replacement of AT25256W-10SI?
All AT25256W-10SI units undergo pre-shipment inspection (PSI). If there is an issue with AT25256W-10SI, 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 AT25256W-10SI part is unused and in its original packaging.
Return procedure for AT25256W-10SI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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