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Microchip Technology 24AA256T/SM
- Part No.:
- 24AA256T/SM
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 8-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
24AA256T/SM.pdf
- Description:
- IC EEPROM 256KBIT I2C 8SOIJ
- Quantity:
- Payment:
- Shipping:
Inventory:4,432
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Product details
Overview
24AA256T/SM from Microchip Technology is a 256-Kbit I²C-compatible serial EEPROM with 32K × 8 organization, 1.7V–5.5V single-supply operation, hardware write-protection via WP pin, and 64-byte page write buffer. It supports up to eight devices on one bus using A0–A2 address inputs and delivers 400 kHz maximum clock frequency at VCC ≥ 2.5V for industrial temperature range (–40°C to +85°C). Used in embedded system configuration storage, sensor calibration data retention, and power-fail-safe parameter logging.
For engineers reviewing the 24AA256T/SM datasheet, 24AA256T/SM pinout, 24AA256T/SM application, or 24AA256T/SM equivalent, key selection considerations include its 1 µA standby current, Schmitt-trigger SDA/SCL inputs for noise immunity, self-timed 5 ms max write cycle, 1 million erase/write endurance, and compatibility with standard I²C protocol including ACK polling and sequential/random read modes.
Technical Context
The 24AA256T/SM implements a two-wire I²C interface with open-drain SDA/SCL pins requiring external pull-ups, internal address pointer for sequential reads, and cascaded addressing via three hardware-configurable chip-select inputs (A0–A2). Its memory array is organized as 32,768 bytes with automatic page boundary wrap detection during writes.
It uses low-power CMOS technology with integrated HV generator for EEPROM programming, Schmitt-trigger input thresholds (0.05 VCC hysteresis), and slope-controlled outputs to suppress ground bounce. Write protection is enforced by sampling the WP pin state at the Stop bit of each write command.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32K × 8) - provides sufficient nonvolatile storage for firmware parameters, device IDs, and calibration coefficients in space-constrained designs. |
| Supply Voltage | 1.7V–5.5V - enables direct interfacing with 1.8V, 3.3V, and 5V microcontrollers without level-shifting. |
| I²C Clock Frequency | Up to 400 kHz (VCC ≥ 2.5V) - supports high-speed configuration updates while maintaining compatibility with legacy I²C peripherals. |
| Page Write Buffer | 64 bytes - reduces total write time for block data by minimizing inter-byte delays and host overhead. |
| Write Endurance | 1,000,000 cycles - ensures long-term reliability in applications requiring frequent parameter updates, such as energy metering or industrial control logs. |
| Data Retention | 200 years - guarantees persistent storage integrity across product lifetime without refresh mechanisms. |
| Standby Current | 1 µA (I-temp.) - minimizes quiescent power draw in battery-backed or always-on systems. |
Pinout & Package
24AA256T/SM is supplied in an 8-lead SOIJ (Small Outline J-Lead) package with 5.28 mm body width, JEDEC MS-012AC compliant footprint, and matte tin (Sn) lead finish. Pin 1 is marked by a notch or beveled corner.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0 | Chip Address Input | Hardwired logic level (VSS/VCC) sets LSB of 3-bit device address; enables up to eight devices on same I²C bus. |
| A1 | Chip Address Input | Second bit of device address; must be fixed before communication begins; no dynamic control during operation. |
| A2 | Chip Address Input | MSB of device address; combined with A0/A1, defines unique I²C client address (1010 A2 A1 A0 R/W). |
| VSS | Ground Reference | Primary return path for all internal circuitry; requires low-impedance connection to system ground plane. |
| SDA | Serial Data I/O | Open-drain bidirectional line; requires external pull-up resistor (2 kΩ typical for 400 kHz); changes only during SCL low. |
| SCL | Serial Clock Input | Input-only clock line driven by master; synchronizes all address/data transfers; edge-sensitive timing critical for ACK generation. |
| WP | Write-Protect Control | Active-high enable: tied to VCC disables all write operations (including byte/page) while preserving read functionality. |
| VCC | Power Supply | Single 1.7–5.5V supply powers EEPROM core, interface logic, and internal charge pump; decoupling capacitor required. |
Key Features
| Feature | Design Value |
|---|---|
| Low-Voltage Operation | Functions down to 1.7V - supports direct integration into ultra-low-power 1.8V systems without voltage translation. |
| Schmitt Trigger Inputs | Hysteresis ≥ 0.05 VCC on SDA/SCL - rejects noise spikes up to 50 ns, eliminating need for external filtering in electrically noisy environments. |
| Page Write Capability | 64-byte buffer with automatic address increment - enables efficient bulk writes with single Stop condition, reducing bus arbitration overhead. |
| Hardware Write Protection | WP pin sampled at Stop bit - prevents accidental overwrites during power transitions or firmware glitches without software intervention. |
| ACK Polling Support | No ACK returned during internal write cycle - allows host to poll completion without fixed delay, optimizing I²C bus utilization. |
Applications
| Industrial Sensor Node | Medical Device Calibration |
|---|---|
Use Scenario: Storing factory-calibrated offset/gain coefficients and real-time sensor drift compensation values in portable blood glucose meters. IC Role / Device Role / Timing Role: Nonvolatile configuration register holding 256-byte calibration profile accessed at power-up and updated after field recalibration. Use Value: Ensures measurement accuracy remains traceable across device lifetime; 200-year data retention eliminates recalibration schedules. |
Use Scenario: Recording patient-specific therapy parameters and usage history in implantable cardiac rhythm management devices. IC Role / Device Role / Timing Role: Secure, tamper-resistant parameter store with WP pin permanently tied to VCC to prevent runtime corruption. Use Value: Meets IEC 62304 safety requirements for persistent data integrity; 1 µA standby current extends battery life beyond 5 years. |
| Smart Energy Meter | Automotive Body Control Module |
Use Scenario: Logging cumulative kWh consumption, tariff switching events, and tamper-detection timestamps during mains power loss. IC Role / Device Role / Timing Role: Power-fail-safe data logger triggered by brown-out detector; writes critical state before shutdown. Use Value: 5 ms max write time ensures full 64-byte page commit within capacitor hold-up time; 1M endurance supports daily logging for >27 years. |
Use Scenario: Storing seat position memory, mirror angle presets, and lighting configuration profiles in automotive door modules. IC Role / Device Role / Timing Role: I²C slave device interfaced to 3.3V MCU; A0–A2 pins hardwired to define unique address on shared vehicle bus. Use Value: AEC-Q100 qualified version available; SOIJ package withstands thermal cycling in under-hood environments; 400 kHz speed enables fast user-setting recall. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar serial EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 24LC256T/SM | Requires minimum 2.5V VCC; 400 kHz max clock; no 1.7V support. | Not suitable for 1.8V systems; otherwise identical pinout, memory map, and I²C protocol. | Select when operating exclusively above 2.5V and cost sensitivity outweighs low-voltage flexibility. |
| AT24C256-10PU-2.7 | 100 kHz max clock at 2.7V; different A0–A2 pin mapping; no WP pin on PDIP variant. | Limited bus speed reduces throughput; lacks hardware write-protect in some packages. | Choose only if legacy AT24Cxx ecosystem mandates compatibility and 400 kHz is unnecessary. |
Compared with 24LC256T/SM and AT24C256-10PU-2.7, the 24AA256T/SM uniquely supports 1.7V operation and guarantees 400 kHz performance across full voltage range, making it optimal for mixed-voltage I²C buses where robustness and speed coexist.
Availability
24AA256T/SM is available at Aetrix Electronics and suitable for industrial sensor nodes, medical device calibration storage, smart energy metering, and automotive body control modules requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for 24AA256T/SM 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 Inc. is a leading provider of microcontroller, analog, FPGA, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.
The 24AA256T/SM belongs to Microchip's 24XX256 family of I²C serial EEPROMs, designed specifically for reliable, low-power nonvolatile data storage in space- and power-constrained embedded systems.
FAQ
What is the minimum supply voltage required for reliable operation of the 24AA256T/SM?
The 24AA256T/SM operates reliably down to 1.7V across the industrial temperature range (–40°C to +85°C). Below 2.5V, its maximum I²C clock frequency is limited to 100 kHz per datasheet DS20001203Y, ensuring stable communication in ultra-low-power 1.8V systems where the 24AA256T/SM maintains full functionality unlike higher-threshold alternatives.
How does the WP pin function on the 24AA256T/SM, and when is it sampled?
The WP (Write-Protect) pin on the 24AA256T/SM is sampled at the Stop bit of each write command. When tied to VCC, it disables all write operations (byte and page) while permitting unrestricted reads. This hardware-level protection prevents accidental overwrites during power transients or firmware errors, and is independent of I²C command sequence - a key reliability feature of the 24AA256T/SM.
Can the 24AA256T/SM perform sequential reads across the entire 32K memory space?
Yes, the 24AA256T/SM supports continuous sequential reads across its full 32,768-byte address space (0000h–7FFFh). After reaching address 7FFFh, the internal address pointer automatically rolls over to 0000h. This behavior is inherent to the 24AA256T/SM's architecture and requires no special addressing - enabling efficient firmware update verification or bulk data dump without host-side address management.
What is the maximum number of 24AA256T/SM devices that can be connected to a single I²C bus?
Up to eight 24AA256T/SM devices can be connected to one I²C bus using unique combinations of A0, A1, and A2 pin states (each tied to VSS or VCC). The 24AA256T/SM's SOIJ package fully supports all three address inputs, enabling full 3-bit addressing - unlike MSOP or SOT-23 variants which omit A0/A1 or all address pins, respectively.
Does the 24AA256T/SM support ACK polling to determine write completion?
Yes, the 24AA256T/SM supports ACK polling: during an internal write cycle, it does not acknowledge any I²C address transmission. A host can repeatedly send a Start condition followed by the write control byte (R/W = 0); when the 24AA256T/SM resumes acknowledging, the write cycle is complete. This eliminates fixed timeout delays and maximizes I²C bus efficiency - a confirmed feature of the 24AA256T/SM per Section 7.0 of its datasheet.
24AA256T/SM Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Programmable:
- Verified
- Memory Type:
- Non-Volatile
- Memory Format:
- EEPROM
- Technology:
- EEPROM
- Memory Size:
- 256Kbit
- Memory Organization:
- 32K x 8
- Memory Interface:
- I2C
- Clock Frequency:
- 400 kHz
- Write Cycle Time - Word, Page:
- 5ms
- Access Time:
- 900 ns
- Voltage - Supply:
- 1.7V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIJ
24AA256T/SM FAQ
1.How can I place an order for 24AA256T/SM through Aetrix?
Please submit a Request for Quotation (RFQ) for 24AA256T/SM 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 24AA256T/SM reliable?
The price and inventory of 24AA256T/SM are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 24AA256T/SM is usually 5 days.
3.What payment methods are accepted for 24AA256T/SM?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 24AA256T/SM transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 24AA256T/SM?
24AA256T/SM orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 24AA256T/SM 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 24AA256T/SM?
For technical support, including 24AA256T/SM datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 24AA256T/SM requirements.
6.How does Aetrix verify that 24AA256T/SM is sourced from the original manufacturer or authorized distributors?
All 24AA256T/SM 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 24AA256T/SM meets industry standards.
7.What is the process for return or replacement of 24AA256T/SM?
All 24AA256T/SM units undergo pre-shipment inspection (PSI). If there is an issue with 24AA256T/SM, 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 24AA256T/SM part is unused and in its original packaging.
Return procedure for 24AA256T/SM:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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