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Microchip Technology AT24C256BN-SH-B
- Part No.:
- AT24C256BN-SH-B
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
AT24C256BN-SH-B.pdf
- Description:
- IC EEPROM 256KBIT I2C 1MHZ 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,366
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Product details
Overview
AT24C256BN-SH-B from Microchip Technology (formerly Atmel) is a 256 Kbit I²C-compatible serial EEPROM organized as 32,768 × 8 bits, operating across 1.8 V to 5.5 V supply, supporting up to 1 MHz clock at 5.0 V and 400 kHz at 1.8 V, with hardware write protection via WP pin and 64-byte page write capability. It is used in industrial sensor calibration storage, embedded system configuration retention, and power-meter firmware parameter backup.
For engineers reviewing the AT24C256BN-SH-B datasheet, AT24C256BN-SH-B pinout, AT24C256BN-SH-B application, or AT24C256BN-SH-B equivalent, key selection considerations include its 1.8–5.5 V wide-voltage operation, Schmitt-triggered noise-immune inputs, 1 million write endurance, 40-year data retention, and support for cascaded multi-device I²C bus configurations up to eight units.
Technical Context
The AT24C256BN-SH-B implements a two-wire I²C interface with bidirectional open-drain SDA and edge-triggered SCL, featuring internal address latching and automatic word-address incrementing during sequential reads. Its memory array is partitioned into 512 pages of 64 bytes each, enabling partial-page writes without erasing adjacent data.
Device addressing uses three hardware-configurable pins (A0–A2) to support up to eight devices on a shared bus, with a fixed 7-bit base address (1010xxx) and R/W bit. Write protection is enforced by the WP pin tied to VCC, disabling all write operations regardless of software commands.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8), sufficient for storing full device configuration tables or firmware metadata in resource-constrained systems |
| Supply Voltage Range | 1.8 V to 5.5 V - enables direct interfacing with both low-power microcontrollers (e.g., ARM Cortex-M0+) and legacy 5 V logic without level shifting |
| I²C Clock Frequency | Up to 1 MHz at 5.0 V / 400 kHz at 1.8 V - balances speed and noise immunity across voltage domains |
| Write Cycle Time | Max 5 ms per byte or page - defines minimum inter-write interval; supports polling-based status detection |
| Endurance & Retention | 1,000,000 write cycles and 40 years data retention at 25°C - meets long-life requirements for industrial field equipment |
| Input Filtering | Schmitt-trigger inputs with 50–100 ns noise suppression - rejects EMI in motor-drive or switching-power environments |
| Page Write Capacity | 64-byte page buffer - reduces I²C transaction overhead when updating contiguous configuration blocks |
Pinout & Package
AT24C256BN-SH-B is supplied in an 8-lead TSSOP package (JEDEC MO-153, 4.4 mm body width), with NiPdAu lead finish for enhanced solderability and corrosion resistance. Pin 1 is marked by a dot in the top-left corner of the package.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A2 | Hardware Device Address Inputs | Set unique 3-bit slave address (000–111); floating defaults to GND but must be externally tied for robust multi-device bus operation |
| SDA | Serial Data Line | Bidirectional open-drain I²C data line requiring external pull-up; supports wire-OR with other I²C peripherals |
| SCL | Serial Clock Input | Master-generated clock signal; rising edge samples data, falling edge drives data - timing-critical for bus compliance |
| WP | Write Protect Control | Active-high hardware lock: tied to VCC disables all writes including page and byte modes, independent of software commands |
| GND | Ground Reference | Primary return path for VCC and I/O signals; must be low-impedance to maintain noise margin on SDA/SCL |
| VCC | Power Supply Input | Accepts 1.8–5.5 V; internal regulation ensures stable core voltage across full range - no external regulator needed |
Key Features
| Feature | Design Value |
|---|---|
| Wide-Voltage I²C Interface | Operates natively from 1.8 V to 5.5 V with full 400 kHz/1 MHz speed support - eliminates level translators in mixed-voltage systems |
| Hardware + Software Write Protection | WP pin disables writes unconditionally; software lock bits provide granular sector-level control - dual-layer security for critical parameters |
| Noise-Immune Inputs | Schmitt-trigger + RC filtering on SDA/SCL - sustains reliable communication in high-noise factory automation or automotive body-control modules |
| Page Write Optimization | 64-byte buffer allows burst writes without repeated start/stop sequences - cuts I²C bus occupancy by >85% vs. byte-by-byte updates |
| Cascadable Bus Architecture | Three address pins enable up to eight AT24C256BN-SH-B devices on one I²C bus - scales storage capacity linearly without additional controllers |
Applications
| Industrial Sensor Calibration | Smart Meter Firmware Storage |
|---|---|
Use Scenario: Storing factory-calibrated offset/gain coefficients and temperature compensation tables for pressure and current sensors in PLC analog input modules. IC Role / Device Role / Timing Role: Nonvolatile configuration register holding persistent calibration data accessed at power-on reset and updated during field recalibration. Use Value: Enables traceable, repeatable sensor accuracy over 10+ years without battery-backed SRAM or external supervision circuitry. | Use Scenario: Retaining tariff schedules, billing history, and cryptographic keys in residential electricity meters operating across 1.8–5.5 V input ranges. IC Role / Device Role / Timing Role: Secure, tamper-resistant parameter store interfaced directly to metering SoC's I²C controller during firmware boot and runtime updates. Use Value: Meets IEC 62056-21 data integrity requirements with 1M-cycle endurance and hardware WP lock against unauthorized firmware modification. |
| Embedded System Configuration | Medical Device Parameter Backup |
Use Scenario: Saving user-defined display brightness, alarm thresholds, and network settings in portable diagnostic ultrasound handsets. IC Role / Device Role / Timing Role: Low-power configuration EEPROM accessed only during startup or menu navigation - draws ≤1 µA in standby at 1.8 V. Use Value: Guarantees settings survive 10,000+ power cycles and 15-year shelf life, satisfying IEC 62304 Class B software safety requirements. | Use Scenario: Backing up patient therapy profiles and calibration logs in infusion pumps where power loss may occur mid-dose. IC Role / Device Role / Timing Role: Fail-safe parameter vault with self-timed 5 ms writes - ensures atomic save of critical dose parameters before shutdown. Use Value: Prevents therapy interruption due to incomplete writes; 40-year retention exceeds FDA 10-year device lifecycle mandate. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| Microchip 24LC256-I/P | Same 256 Kbit capacity and I²C interface, but rated for industrial temp only (−40°C to +85°C); PDIP package, no NiPdAu finish | Lacks TSSOP footprint and enhanced lead finish - unsuitable for high-density PCBs or harsh-humidity environments | Select when through-hole assembly or cost-sensitive industrial designs prioritize legacy packaging over miniaturization |
| ON Semiconductor CAT24C256WI-GT3 | Identical 256 Kbit organization and 1.8–5.5 V range; same 8-lead TSSOP package and NiPdAu finish; supports 1 MHz up to 2.5 V only | Lower max clock frequency at 1.8 V (400 kHz only) and reduced AC timing margins - limits throughput in high-speed logging applications | Choose for drop-in replacement where 400 kHz bus speed suffices and second-source assurance is required |
Compared with AT24C256BN-SH-B, the 24LC256-I/P trades miniaturization for through-hole robustness, while the CAT24C256WI-GT3 offers footprint compatibility but constrains maximum I²C throughput at low voltage - making AT24C256BN-SH-B optimal for space-constrained, wide-voltage, high-speed embedded storage.
Availability
AT24C256BN-SH-B is available at Aetrix Electronics and suitable for industrial sensor calibration, smart meter firmware storage, and embedded system configuration requiring stable component supply across extended temperature and voltage ranges.
Supply support for AT24C256BN-SH-B 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 broad industrial and automotive qualification coverage.
The AT24C256BN-SH-B belongs to Microchip's AT24Cxx family of I²C EEPROMs, designed specifically for reliable, low-power, multi-voltage data retention in embedded systems where firmware robustness and long-term field reliability are critical.
FAQ
What is the maximum I²C clock frequency supported by the AT24C256BN-SH-B at 1.8 V?
The AT24C256BN-SH-B supports a maximum I²C clock frequency of 400 kHz when operating at 1.8 V. This is specified in Table 3-3 of the datasheet under "AC Characteristics (Industrial Temperature)" and reflects the device's optimized noise immunity and timing margins at low voltage. At higher supply voltages (2.5 V and 5.0 V), the clock frequency increases to 1 MHz. The AT24C256BN-SH-B maintains full protocol compliance across this range without requiring external timing adjustments.
Does the AT24C256BN-SH-B require external pull-up resistors on SDA and SCL lines?
Yes, the AT24C256BN-SH-B requires external pull-up resistors on both SDA and SCL lines because its I²C interface uses open-drain outputs. The recommended values are 1.3 kΩ for 2.5 V and 5.5 V operation, and 10 kΩ for 1.8 V operation, as defined in Note 2 of Table 3-3. These values ensure proper rise times and noise margin while accommodating bus capacitance up to 400 pF. The AT24C256BN-SH-B does not include internal pull-ups.
How many AT24C256BN-SH-B devices can share the same I²C bus?
Up to eight AT24C256BN-SH-B devices can share a single I²C bus. This is enabled by the three hardware address pins (A0, A1, A2), each configurable as logic high or low to generate a unique 3-bit device address. The base I²C address is 1010xxx, where xxx corresponds to A2–A0. All eight combinations (000 to 111) are valid and electrically isolated - no software arbitration or address conflict resolution is needed for AT24C256BN-SH-B multi-drop operation.
What happens when the WP pin of the AT24C256BN-SH-B is left unconnected?
When the WP pin of the AT24C256BN-SH-B is left unconnected, it is internally pulled down to GND, enabling normal write operations. However, the datasheet explicitly warns that capacitive coupling in real-world applications may cause unintended WP state transitions. Therefore, Microchip recommends always connecting WP to a defined voltage - either GND for full write access or VCC to disable all writes - using a ≤10 kΩ resistor if pulled up. Leaving WP floating violates robust design practice for AT24C256BN-SH-B deployments.
Is the AT24C256BN-SH-B compatible with standard I²C protocol analyzers and development tools?
Yes, the AT24C256BN-SH-B is fully compatible with standard I²C protocol analyzers (e.g., Total Phase Beagle, Saleae Logic Pro) and development tools (e.g., Arduino Wire library, STM32 HAL_I2C). It adheres strictly to the NXP I²C-bus specification Rev. 6, including START/STOP conditions, ACK/NACK signaling, 7-bit addressing, and clock stretching behavior. All timing parameters (tLOW, tHIGH, tSU.STA, etc.) are verified across voltage and temperature ranges - ensuring interoperability with off-the-shelf I²C test and debug infrastructure for AT24C256BN-SH-B integration.
AT24C256BN-SH-B Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm 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:
- 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
AT24C256BN-SH-B FAQ
1.How can I place an order for AT24C256BN-SH-B through Aetrix?
Please submit a Request for Quotation (RFQ) for AT24C256BN-SH-B 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 AT24C256BN-SH-B reliable?
The price and inventory of AT24C256BN-SH-B are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT24C256BN-SH-B is usually 5 days.
3.What payment methods are accepted for AT24C256BN-SH-B?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT24C256BN-SH-B transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT24C256BN-SH-B?
AT24C256BN-SH-B orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT24C256BN-SH-B 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 AT24C256BN-SH-B?
For technical support, including AT24C256BN-SH-B datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT24C256BN-SH-B requirements.
6.How does Aetrix verify that AT24C256BN-SH-B is sourced from the original manufacturer or authorized distributors?
All AT24C256BN-SH-B 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 AT24C256BN-SH-B meets industry standards.
7.What is the process for return or replacement of AT24C256BN-SH-B?
All AT24C256BN-SH-B units undergo pre-shipment inspection (PSI). If there is an issue with AT24C256BN-SH-B, 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 AT24C256BN-SH-B part is unused and in its original packaging.
Return procedure for AT24C256BN-SH-B:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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