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Microchip Technology AT24C256BW-SH-T
- Part No.:
- AT24C256BW-SH-T
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
AT24C256BW-SH-T.pdf
- Description:
- IC EEPROM 256KBIT I2C 1MHZ 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,120
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Product details
Overview
AT24C256BW-SH-T from Microchip Technology (formerly Atmel) is a 256K-bit (32,768 × 8) two-wire serial EEPROM with 1.8V to 5.5V operation, 64-byte page write capability, and hardware write protection via the WP pin. It supports up to 1 MHz I²C communication at 5.0V/2.7V/2.5V and 400 kHz at 1.8V, and is used in industrial control systems for parameter storage and firmware configuration retention.
For engineers reviewing the AT24C256BW-SH-T datasheet, AT24C256BW-SH-T pinout, AT24C256BW-SH-T application, or AT24C256BW-SH-T equivalent, key selection criteria include its 1.8V–5.5V supply range, 40-year data retention, 1 million write cycles, Schmitt-trigger noise-immune inputs, and support for cascaded bus configurations with up to eight devices.
Technical Context
The AT24C256BW-SH-T implements a standard two-wire (I²C-compatible) interface with open-drain SDA and active-high SCL, supporting both byte and 64-byte page writes. Its internal address counter enables sequential reads across memory boundaries, and hardware device addressing uses A0–A2 pins to allow up to eight devices on one bus.
It features an internal high-voltage pump for EEPROM programming, self-timed write cycles (max 5 ms), and dual-level data protection: hardware write inhibit via WP pin tied to VCC and software-controlled lock bits. Input filtering and Schmitt triggers ensure robust operation in electrically noisy industrial environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8), sufficient for storing calibration tables, device IDs, or boot configuration in embedded controllers. |
| Supply Voltage Range | 1.8 V to 5.5 V - enables direct interfacing with 1.8V logic, 3.3V microcontrollers, and legacy 5V systems without level shifters. |
| I²C Speed Support | 400 kHz @ 1.8V; 1 MHz @ 2.5V/5.0V - balances speed and noise immunity across voltage domains. |
| Write Endurance | 1,000,000 cycles - supports frequent logging or runtime parameter updates in telemetry and metering applications. |
| Data Retention | 40 years at +25°C - ensures long-term reliability for unattended infrastructure equipment and medical devices. |
| Page Write Size | 64 bytes per page - reduces I²C transaction overhead when updating contiguous configuration blocks. |
| Operating Temperature | −40°C to +85°C - qualified for industrial-grade deployment in factory automation and outdoor electronics. |
Pinout & Package
AT24C256BW-SH-T is packaged in an 8-lead TSSOP (8A2) with 0.65 mm pitch, 4.4 mm × 3.0 mm body, and 1.05 mm max height - optimized for space-constrained PCB layouts in portable and modular industrial designs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A2 | Hardware Device Address Inputs | Enable up to eight AT24C256BW-SH-T devices on one I²C bus; must be hardwired to GND or VCC - floating states are internally pulled down but not recommended. |
| SDA | Serial Data Line | Bidirectional, open-drain I²C data line; requires external pull-up resistor and supports wire-OR with other I²C peripherals. |
| SCL | Serial Clock Input | Positive-edge clock input for data latching; timing-critical path requiring controlled rise/fall times (≤300 ns fall, ≤300 ns rise). |
| WP | Write Protect Control | Active-high hardware lock: tied to VCC disables all writes; tied to GND enables full read/write access. |
| GND | Ground Reference | Primary return path for all internal circuitry and I/O; must be low-impedance connection to minimize noise coupling into SDA/SCL. |
| VCC | Power Supply Input | Accepts 1.8–5.5 V; decoupling capacitor (0.1 µF ceramic) required within 10 mm of pin for stable write-cycle operation. |
Key Features
| Feature | Design Value |
|---|---|
| Schmitt-trigger, filtered inputs | Suppresses EMI-induced glitches on SDA/SCL, enabling reliable I²C operation in motor-drive or switching-power-supply proximity. |
| 64-byte page write mode | Reduces I²C bus occupancy by 94% vs. 64 individual byte writes - critical for real-time systems with tight latency budgets. |
| Self-timed write cycle (5 ms max) | Eliminates need for host MCU to poll status or manage timing; simplifies firmware and avoids bus contention during writes. |
| 1.8V–5.5V wide supply range | Supports single-supply designs across battery-powered sensors (1.8V), IoT edge nodes (3.3V), and legacy industrial PLCs (5V). |
| Hardware + software write protection | WP pin provides immediate physical lockout; combined with address-range locking, prevents accidental overwrites of critical firmware parameters. |
Applications
| Industrial Sensor Calibration | Smart Meter Firmware Storage |
|---|---|
Use Scenario: Storing temperature, pressure, and offset compensation coefficients during factory calibration of analog sensor modules. IC Role / Device Role / Timing Role: Nonvolatile configuration register holding trim values accessed at power-up by ADC driver firmware. Use Value: Enables field-replaceable sensor heads with unique calibration profiles stored independently of main controller firmware. | Use Scenario: Retaining tariff schedules, billing counters, and cryptographic keys in electricity/water/gas meters operating for >10 years without maintenance. IC Role / Device Role / Timing Role: Secure, long-life data vault synchronized with metrology ICs via I²C during meter initialization and firmware updates. Use Value: Meets ANSI C12.19 and IEC 62056 requirements for 40-year data integrity and tamper-resistant parameter storage. |
| PLC Configuration Backup | Medical Device Parameter Archiving |
Use Scenario: Saving ladder logic scan settings, I/O mapping, and alarm thresholds in programmable logic controllers deployed in manufacturing lines. IC Role / Device Role / Timing Role: Persistent configuration store updated only during commissioning or reprogramming; accessed during cold start. Use Value: Ensures deterministic boot behavior and eliminates manual setup after power loss or firmware reload. | Use Scenario: Recording device-specific operational limits, user preferences, and regulatory compliance logs in portable diagnostic equipment (e.g., ultrasound, infusion pumps). IC Role / Device Role / Timing Role: FDA 21 CFR Part 11-compliant audit trail buffer with write-cycle wear leveling managed by host MCU. Use Value: Supports traceability and recall readiness while meeting IEC 62304 safety lifecycle requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| M24256-BWMN6TP | Same 256K-bit capacity, 1.7–5.5V supply, but uses different die revision and offers 100 kHz/400 kHz/1 MHz speeds across voltage bands; no internal pull-down on A0–A2. | Preferred in automotive-qualified designs due to AEC-Q100 Grade 2 rating; lacks NiPdAu lead finish option. | Select M24256-BWMN6TP when AEC-Q100 qualification or alternate lead finish is required; verify A0–A2 termination in layout. |
| BR24G256FJ-3GE2 | 256K-bit, 1.6–5.5V, supports 1 MHz up to 1.7V; includes built-in write-cycle suspend/resume and enhanced ESD protection (±8 kV HBM). | Targeted at high-noise environments like motor drives and inverters where dynamic write interruption is common. | Choose BR24G256FJ-3GE2 when system-level ESD robustness or interruptible writes are mandatory; confirm I²C timing compatibility with host controller. |
Compared with M24256-BWMN6TP and BR24G256FJ-3GE2, the AT24C256BW-SH-T delivers proven industrial reliability with NiPdAu lead finish for solderability assurance, tighter 40-year retention spec, and explicit support for cascaded multi-device bus topologies - making it optimal for cost-sensitive, high-volume industrial control designs.
Availability
AT24C256BW-SH-T is available at Aetrix Electronics and suitable for industrial automation, smart metering, and medical device manufacturing requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.
Supply support for AT24C256BW-SH-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 acquired Atmel in 2016 and maintains full product continuity, technical documentation, and manufacturing for the AT24Cxx EEPROM family.
The AT24C256BW-SH-T belongs to Microchip's serial EEPROM product line, designed specifically for robust, low-power nonvolatile data storage in industrial, automotive, and consumer systems requiring guaranteed 40-year data retention and 1-million-cycle endurance.
FAQ
What is the maximum I²C clock frequency supported by the AT24C256BW-SH-T?
The AT24C256BW-SH-T supports 1 MHz I²C operation at VCC = 5.0V, 2.7V, or 2.5V, and 400 kHz at VCC = 1.8V. These speed grades are voltage-dependent and validated per AC Characteristics Table 3-3 in the datasheet. Exceeding these frequencies may cause ACK failures or data corruption, especially under capacitive bus loads exceeding 400 pF.
Does the AT24C256BW-SH-T require external pull-up resistors on SDA and SCL lines?
Yes, the AT24C256BW-SH-T requires external pull-up resistors on both SDA and SCL lines because its I/O pins are open-drain. Recommended values are 1.3 kΩ for 2.5V/5.5V operation and 10 kΩ for 1.8V operation, per AC measurement conditions in the datasheet. Incorrect pull-up strength causes timing violations or bus lockup.
How does the write protect (WP) pin function on the AT24C256BW-SH-T?
When WP is tied to VCC, all write operations to the AT24C256BW-SH-T memory array are inhibited - including byte, page, and sequential writes. When WP is grounded, full read/write access is enabled. The pin has an internal pull-down, but Atmel recommends hardwiring it to avoid noise-induced false writes in industrial environments.
Can multiple AT24C256BW-SH-T devices share the same I²C bus?
Yes, up to eight AT24C256BW-SH-T devices can share one I²C bus using hardware address pins A0, A1, and A2. Each device must have a unique combination of these pins tied to GND or VCC to generate distinct 3-bit device addresses (000–111), enabling individual addressing within the standard 7-bit I²C protocol.
What is the endurance specification for the AT24C256BW-SH-T, and how is it tested?
The AT24C256BW-SH-T guarantees 1,000,000 write cycles per memory location, tested at 25°C and 3.3V using page-mode writes. This endurance applies to each individual byte address and is characterized - not 100% tested - per datasheet Note 1 in Table 3-3. Wear leveling must be implemented in firmware for applications exceeding this limit.
AT24C256BW-SH-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- 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:
- I2C
- Clock Frequency:
- 1 MHz
- Write Cycle Time - Word, Page:
- 5ms
- Access Time:
- 550 ns
- Voltage - Supply:
- 1.8V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
AT24C256BW-SH-T FAQ
1.How can I place an order for AT24C256BW-SH-T through Aetrix?
Please submit a Request for Quotation (RFQ) for AT24C256BW-SH-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 AT24C256BW-SH-T reliable?
The price and inventory of AT24C256BW-SH-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT24C256BW-SH-T is usually 5 days.
3.What payment methods are accepted for AT24C256BW-SH-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT24C256BW-SH-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT24C256BW-SH-T?
AT24C256BW-SH-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT24C256BW-SH-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 AT24C256BW-SH-T?
For technical support, including AT24C256BW-SH-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT24C256BW-SH-T requirements.
6.How does Aetrix verify that AT24C256BW-SH-T is sourced from the original manufacturer or authorized distributors?
All AT24C256BW-SH-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 AT24C256BW-SH-T meets industry standards.
7.What is the process for return or replacement of AT24C256BW-SH-T?
All AT24C256BW-SH-T units undergo pre-shipment inspection (PSI). If there is an issue with AT24C256BW-SH-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 AT24C256BW-SH-T part is unused and in its original packaging.
Return procedure for AT24C256BW-SH-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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