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Microchip Technology AT24C256B-PU
- Part No.:
- AT24C256B-PU
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
AT24C256B-PU.pdf
- Description:
- IC EEPROM 256KBIT I2C 1MHZ 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,326
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Product details
Overview
AT24C256B-PU from Microchip Technology (formerly Atmel) is a 256 Kbit (32,768 × 8) two-wire serial EEPROM with 1.8 V to 5.5 V operation, 64-byte page write capability, hardware write protection via WP pin, and 1 MHz I²C compatibility at 5.0 V/2.7 V/2.5 V. It serves as nonvolatile configuration storage in microcontroller-based industrial control modules.
For engineers reviewing the AT24C256B-PU datasheet, AT24C256B-PU pinout, AT24C256B-PU application, or AT24C256B-PU equivalent, key selection criteria include its PDIP-8 package, 5 ms max self-timed write cycle, 1 million write endurance, 40-year data retention, and Schmitt-triggered noise-immune I²C interface.
Technical Context
The AT24C256B-PU implements a standard two-wire (I²C-compatible) serial interface with open-drain SDA and positive-edge-triggered SCL. Its internal address counter supports current-address, random-address, and sequential reads, while cascading up to eight devices on one bus is enabled by hardwired A0–A2 inputs.
Write operations support both byte and 64-byte page modes, with automatic address roll-over within pages and acknowledge polling for write-cycle completion detection. The device uses an internal high-voltage pump and timing circuit for EEPROM programming, eliminating external high-voltage requirements.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8), enabling storage of firmware parameters or calibration data for embedded systems |
| Supply Voltage Range | 1.8 V to 5.5 V - supports direct interfacing with 1.8 V, 2.5 V, 3.3 V, and 5 V microcontrollers without level shifting |
| I²C Clock Frequency | Up to 1 MHz at 5.0 V/2.7 V/2.5 V; 400 kHz at 1.8 V - balances speed and noise immunity across voltage grades |
| Page Write Capacity | 64 bytes per page - reduces write transaction overhead versus byte writes, improving system-level update efficiency |
| Write Endurance | 1,000,000 cycles - suitable for applications requiring frequent parameter logging or field-updatable settings |
| Data Retention | 40 years at +25°C - ensures long-term reliability in unattended or maintenance-free deployments |
| Write Protect | Hardware-enabled via WP pin tied to VCC - prevents accidental overwrites during power-up/down or firmware glitches |
Pinout & Package
AT24C256B-PU is supplied in an 8-lead JEDEC-standard Plastic Dual Inline Package (PDIP), 0.300" wide body (package code 8P3), with through-hole mounting and industry-standard pin spacing.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A2 | Device Address Inputs | Hardwired to GND/VCC to configure one of eight possible I²C slave addresses; floating pins default to GND but must be externally biased for robustness |
| SDA | Serial Data Line | Bidirectional, open-drain I²C data line requiring external pull-up; supports wire-OR with other open-drain devices on same bus |
| SCL | Serial Clock Input | Positive-edge clock input for synchronous data transfer; Schmitt-triggered for noise immunity in electrically noisy environments |
| WP | Write Protect Control | Active-high hardware lock: tied to VCC disables all writes; tied to GND enables normal read/write operation |
| GND | Ground Reference | Primary signal and power return path; must be low-impedance to ensure stable I²C signaling and EEPROM reliability |
| VCC | Power Supply | Single-supply input supporting 1.8–5.5 V; powers internal logic, HV pump, and memory array |
Key Features
| Feature | Design Value |
|---|---|
| Schmitt-triggered inputs | Suppresses digital noise on SCL/SDA lines, enabling reliable operation in industrial EMI environments |
| Self-timed write cycle | Eliminates need for external timing control - host MCU can poll ACK or wait fixed 5 ms before next access |
| 64-byte page write mode | Reduces I²C transaction count by up to 64× versus byte writes, lowering bus occupancy and host CPU load |
| Internal address counter | Automatically increments after each read/write, enabling efficient sequential access without repeated address commands |
| Cascadable architecture | Supports up to eight AT24C256B-PU devices on one I²C bus using A0–A2 address bits - simplifies multi-peripheral designs |
Applications
| Industrial PLC Configuration Storage | Medical Device Calibration Data |
|---|---|
Use Scenario: Storing I/O mapping tables, PID tuning parameters, and alarm thresholds in programmable logic controllers operating in factory-floor environments. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed via I²C during boot and runtime reconfiguration. Use Value: Ensures deterministic startup behavior and retains critical settings across power cycles and firmware updates. | Use Scenario: Holding sensor offset/gain coefficients and patient-specific therapy profiles in portable infusion pumps and diagnostic monitors. IC Role / Device Role / Timing Role: Secure, long-life data repository for FDA-regulated calibration records and usage logs. Use Value: Meets 40-year data retention requirement for medical device traceability and regulatory compliance. |
| Smart Energy Meter Firmware Settings | Automotive Body Control Module NVM |
Use Scenario: Saving tariff schedules, demand-response flags, and metering calibration constants in ANSI C12.22-compliant smart meters deployed in utility grids. IC Role / Device Role / Timing Role: Low-power, tamper-resistant EEPROM interfaced to 3.3 V MCU over I²C with WP pin grounded for secure writes. Use Value: Enables field-upgradable billing logic while preventing unauthorized modification of revenue-critical parameters. | Use Scenario: Storing door lock actuation history, mirror position presets, and lighting configuration in automotive BCMs operating across −40°C to +85°C. IC Role / Device Role / Timing Role: Industrial-temperature-grade serial EEPROM providing robust NVM for comfort and convenience features. Use Value: Delivers 1M write cycles and 40-year retention under thermal cycling and vibration stress typical of vehicle cabins. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 24LC256-I/P | Microchip PIC-compatible 256 Kbit EEPROM; identical 8P3 PDIP package, 1.8–5.5 V range, and 64-byte page write - but rated only to 100 k write cycles and 200-year retention at +25°C (vs. 1 M/40 yr) | Lower endurance makes it less suitable for high-write-frequency logging; preferred where cost sensitivity outweighs longevity | Select 24LC256-I/P when BOM cost is primary constraint and write frequency is ≤100×/day |
| CAT24C256WI-GT3 | ON Semiconductor 256 Kbit EEPROM in 8-lead SOIC; supports same voltage range and I²C speeds, but lacks hardware WP pin - relies on software write protection only | No dedicated WP pin increases risk of accidental overwrite during brown-out or reset; requires tighter firmware control | Choose CAT24C256WI-GT3 only if board layout already uses SOIC and WP functionality is implemented in software |
Compared with 24LC256-I/P and CAT24C256WI-GT3, the AT24C256B-PU provides superior write endurance (1 M vs. 100 k cycles) and guaranteed hardware write protection - making it optimal for industrial and medical applications demanding long-term data integrity and fault resilience.
Availability
AT24C256B-PU is available at Aetrix Electronics and suitable for industrial PLCs, medical instrumentation, smart energy meters, and automotive body control modules requiring stable component supply and long-lifecycle support.
Supply support for AT24C256B-PU 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, FPGA, and memory solutions, with broad industrial and automotive qualification coverage.
The AT24C256B-PU belongs to Microchip's legacy AT24Cxx serial EEPROM product line, designed specifically for reliable, low-power, I²C-based nonvolatile storage in space-constrained and thermally demanding embedded systems.
FAQ
What is the maximum I²C clock frequency supported by the AT24C256B-PU?
The AT24C256B-PU supports up to 1 MHz I²C clock frequency at VCC = 5.0 V, 2.7 V, or 2.5 V, and 400 kHz at VCC = 1.8 V. These values are specified in the AC Characteristics table (Table 3-3) and reflect guaranteed timing margins across the full industrial temperature range (−40°C to +85°C). The device uses Schmitt-triggered inputs to maintain signal integrity at these speeds.
Does the AT24C256B-PU require an external high-voltage supply for write operations?
No, the AT24C256B-PU does not require an external high-voltage supply. It integrates an internal high-voltage charge pump and timing circuit that generates the necessary programming voltage from the standard VCC supply (1.8 V to 5.5 V). This eliminates external components and simplifies system design - all write operations are fully self-contained within the AT24C256B-PU.
How many AT24C256B-PU devices can share the same I²C bus?
Up to eight AT24C256B-PU devices can share a single I²C bus. This is achieved using the three hardware address inputs A0, A1, and A2, which combine to form a 3-bit device address. Each device must have a unique combination of A0–A2 tied to VCC or GND. The AT24C256B-PU's device address prefix is "1010", allowing full 8-device addressing without conflict.
What is the purpose of the WP pin on the AT24C256B-PU, and how should it be connected?
The WP (Write Protect) pin on the AT24C256B-PU provides hardware-level write inhibition. When WP is connected to VCC, all write operations (byte and page) are blocked; when tied to GND, writes are enabled. Although internally pulled down, Atmel recommends hardwiring WP to a known state (GND or VCC) using ≤10 kΩ resistors to prevent capacitive coupling-induced glitches - a critical design practice for field-reliable AT24C256B-PU implementations.
Is the AT24C256B-PU compatible with standard I²C protocol and controllers?
Yes, the AT24C256B-PU is fully compliant with the standard two-wire I²C protocol. It supports START/STOP conditions, 7-bit slave addressing (with R/W bit), ACK/NACK handshaking, and standard read/write sequences including current-address, random-address, and sequential reads. It interoperates seamlessly with any I²C master - including Microchip PIC, STMicro STM32, NXP LPC, and TI MSP430 microcontrollers - without protocol translation.
AT24C256B-PU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- 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:
- Through Hole
- Supplier Device Package:
- 8-PDIP
AT24C256B-PU FAQ
1.How can I place an order for AT24C256B-PU through Aetrix?
Please submit a Request for Quotation (RFQ) for AT24C256B-PU 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 AT24C256B-PU reliable?
The price and inventory of AT24C256B-PU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT24C256B-PU is usually 5 days.
3.What payment methods are accepted for AT24C256B-PU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT24C256B-PU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT24C256B-PU?
AT24C256B-PU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT24C256B-PU 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 AT24C256B-PU?
For technical support, including AT24C256B-PU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT24C256B-PU requirements.
6.How does Aetrix verify that AT24C256B-PU is sourced from the original manufacturer or authorized distributors?
All AT24C256B-PU 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 AT24C256B-PU meets industry standards.
7.What is the process for return or replacement of AT24C256B-PU?
All AT24C256B-PU units undergo pre-shipment inspection (PSI). If there is an issue with AT24C256B-PU, 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 AT24C256B-PU part is unused and in its original packaging.
Return procedure for AT24C256B-PU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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