24AA256-I/SN - 256Kbit I2C EEPROM, 400kHz, 1.7-5.5V | Microchip
MPN: 24AA256-I/SN ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.69 | $0.69 |
| 10 | $0.62 | $6.20 |
| 100 | $0.52 | $52.00 |
| 500 | $0.45 | $225.00 |
| 1,000 | $0.39 | $390.00 |
24AA256-I/SN Overview
A serial EEPROM is a non-volatile memory device that retains data through power cycles and is written/read serially over a low-pin-count bus such as I2C, SPI, or Microwire. EEPROMs sit within the non-volatile memory hierarchy alongside Flash and FRAM, sitting beneath NAND/NOR Flash in write endurance but above Flash in random-access byte-level write granularity. The 24AA256 belongs to the broader EEPROM family -> non-volatile memory -> memory IC -> integrated circuit taxonomy, and is a drop-in member of Microchip's 24XX256 I2C EEPROM series.
Key features include hardware write-protect via the WP pin, software data protection via a special 4-bit sequence to prevent inadvertent writes, and >1 million erase/write cycles per byte with >200-year data retention. The 24AA256 operates at very low standby current (typically 1 uA) and read current (typically 1 mA), making it ideal for battery-powered designs where minimizing quiescent drain is critical.
The device uses a CMOS process with a built-in Schmitt trigger on the SCL/SDA inputs for noise-tolerant bus operation, plus a cascadable 3-bit hardware address scheme (A0, A1, A2) that lets up to eight devices share the same I2C bus without bus contention. Random and sequential read modes both supported. The architecture is optimized for low-power, low-density non-volatile storage rather than high-throughput logging.
Typical applications include storing user preferences in consumer electronics, configuration parameters in industrial control modules, calibration constants in test and measurement instruments, and black-box event logs in portable medical devices. The wide voltage range supports direct attachment to 1.8V, 3.3V, and 5V rails without level shifters.
When designing with this part, add proper I2C pull-up resistors (typically 2.2-10 kohm depending on bus capacitance and speed) on SCL and SDA. Reserve a 5 ms write-cycle time per page-write operation in firmware to avoid polling hazards, and tie WP low only if write protection is not needed; tying WP high freezes the memory map.
This page synthesizes distributor pricing, drop-in same-package alternatives (24LC256, 24FC256, AT24C256C), and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for 24AA256-I/SN — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with 24AA256-I/SN (same form factor and footprint) — differing in Package, Memory Type, Endurance, Memory Size, Interface.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
24LC256-I/SN
✅ Drop-In📋 Reference alternative (not in catalog)
24FC256-I/SN
✅ Drop-In📋 Reference alternative (not in catalog)
24AA256T-I/SN
✅ Drop-In📋 Reference alternative (not in catalog)
AT24C256C-SSHL-T
✅ Drop-In📋 Reference alternative (not in catalog)
BR24L256FJ-WE2
✅ Drop-In📋 Reference alternative (not in catalog)
M24256-BR
✅ Drop-In📋 Reference alternative (not in catalog)
24AA256-I/SN Maximum Ratings & Electrical Characteristics
| Memory Type | EEPROM (Electrically Erasable PROM) |
| Memory Size | 256 Kbit (32K x 8) |
| Memory Organization | 32K x 8 (32,768 bytes) |
| Interface | I2C (2-wire serial) |
| Bus Speed | 400 kHz (Fast-mode) |
| Supply Voltage Range | 1.7 V to 5.5 V |
| Access Time | 900 ns |
| Page Write Size | 64 bytes |
| Write Cycle Time | 5 ms (max) |
| Endurance | >1,000,000 erase/write cycles per byte |
| Data Retention | >200 years |
| Standby Current | 1 uA (typical) |
| Read Current | 1 mA (typical at 400 kHz) |
| Hardware Address Pins | 3 (A0, A1, A2) for up to 8 devices on bus |
| Write Protect Pin | Yes (WP, active-high) |
| Operating Temperature Range | -40C to +85C (Industrial) |
| Package | 8-pin SOIC (SN, 3.90 mm body) |
| Mounting Type | Surface Mount |
| MSL Level | 1 (unlimited floor life) |
| RoHS Status | Compliant |
24AA256-I/SN Pin Configuration
| Pin 1 | A0 — Hardware slave address bit 0 (tie to VCC or GND) |
| Pin 2 | A1 — Hardware slave address bit 1 (tie to VCC or GND) |
| Pin 3 | A2 — Hardware slave address bit 2 (tie to VCC or GND) |
| Pin 4 | VSS — Ground |
| Pin 5 | SDA — Serial data (I2C bidirectional, open-drain, requires pull-up) |
| Pin 6 | SCL — Serial clock (I2C input, requires pull-up) |
| Pin 7 | WP — Write protect (active high, ties to GND for normal writes) |
| Pin 8 | VCC — Supply voltage, 1.7V to 5.5V |
Typical Applications
24AA256-I/SN is suitable for 6 applications: Industrial Sensor Calibration Storage, Consumer Electronics User Preference Memory, Medical Device Event Logging, IoT Module Configuration Storage, Test and Measurement Instrument Setup Memory, Automotive Accessory Parameter Storage.
Industrial Sensor Calibration Storage
The 24AA256-I/SN is well suited to store factory calibration constants in industrial sensors and transducers where each unit is individually trimmed at production and the data must persist for the life of the equipment. The 1.7V-5.5V VCC range lets the EEPROM ride on the same 3.3V rail that powers the sensor MCU and the 8-SOIC footprint sits compactly behind a sensor housing. With >1M write cycles per byte and >200-year retention per the Microchip datasheet, calibration drift correction coefficients and unit serial numbers remain intact through decades of field operation, even if the host MCU is replaced or firmware is reflashed.
Recommended
Consumer Electronics User Preference Memory
In consumer appliances, smart-home devices, and wearable electronics, the 24AA256-I/SN provides 32 Kbytes of non-volatile storage for user preferences, last-mode memory, and learned behavior that must survive power cycles. The 1 uA typical standby current from the Microchip datasheet makes it ideal for battery-powered wearables where quiescent drain matters, and the 400 kHz I2C bus allows fast access at boot time. Designers wire the WP pin low by default and use the 64-byte page write to commit preference changes efficiently, with the 5 ms write cycle time easily absorbed in non-critical background tasks.
Recommended
Medical Device Event Logging
Portable medical devices such as glucose meters, blood pressure monitors, and infusion pumps use the 24AA256-I/SN as an event log buffer that records dosing events, alarms, and operator actions for later review. The Microchip 24AA256 datasheet confirms >200-year data retention, satisfying medical device lifetime requirements, and the 1.7V-5.5V range lets the EEPROM run directly off a single Li-ion cell. The 8-SOIC package simplifies FDA submission documentation since it is a standard JEDEC outline, and the I2C interface allows the host MCU to log events asynchronously without consuming GPIO.
Recommended
IoT Module Configuration Storage
Wi-Fi, BLE, and LoRa IoT modules frequently store network credentials, encryption keys, and provisioning data in a companion EEPROM like the 24AA256-I/SN, offloading flash wear from the host MCU. The 400 kHz I2C interface from the Microchip 24AA256 datasheet is fast enough to keep up with TLS handshake key retrievals, and the 8-SOIC package is easy to place alongside a small module footprint. With 32 Kbytes of storage, the EEPROM can hold multiple SSID/password pairs, certificate fragments, and OTA rollback markers without burning the host flash endurance budget.
Recommended
Test and Measurement Instrument Setup Memory
Bench-top test instruments, data loggers, and laboratory meters use the 24AA256-I/SN to retain user-defined test profiles, channel configurations, and last-known instrument state across power cycles. The wide 1.7V-5.5V VCC range per the Microchip datasheet tolerates noisy lab supplies and 5V/3.3V mixed-voltage designs. The 8-SOIC footprint places the EEPROM near the MCU's I2C pins with minimal board real estate, and the 64-byte page write enables fast batch updates of multi-channel calibration tables.
Recommended
Automotive Accessory Parameter Storage
Aftermarket automotive accessories and non-safety in-cabin modules such as HUD projectors, dash cameras, and infotainment add-ons use the 24AA256-I/SN for storing user preferences, GPS waypoints, and dashcam clip bookmarks. While the part is industrial-grade -40C to +85C per the Microchip 24AA256 datasheet (not AEC-Q100 qualified), it tolerates cabin temperature swings without an external heater. The 400 kHz I2C bus integrates cleanly with automotive-grade MCUs, and the 8-SOIC footprint simplifies thermal management in enclosed modules.
Recommended
Recommended Products Summary
Engineering reference data for 24AA256-I/SN — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | 24LC256-I/SN | 24FC256-I/SN | AT24C256C-SSHL-T | BR24L256FJ-WE2 | M24256-BR |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology (Atmel) | ROHM Semiconductor | STMicroelectronics |
| Package | 8-SOIC (SN) | 8-SOIC (SN) - same | 8-SOIC (SN) - same | 8-SOIC (SN) - same | 8-SOIC (SN) - same | 8-SOIC (SN) - same |
| Memory Size | 256 Kbit (32K x 8) | 256 Kbit (32K x 8) | 256 Kbit (32K x 8) | 256 Kbit (32K x 8) | 256 Kbit (32K x 8) | 256 Kbit (32K x 8) |
| Supply Voltage Range | 1.7 V to 5.5 V | 2.5 V to 5.5 V | 1.7 V to 5.5 V | 1.7 V to 5.5 V | 2.5 V to 5.5 V | 2.5 V to 5.5 V |
| Max I2C Clock | 400 kHz | 400 kHz | 1 MHz | 400 kHz | 400 kHz | 400 kHz |
| Page Write Size | 64 bytes | 64 bytes | 64 bytes | 64 bytes | 64 bytes | 64 bytes |
| Endurance | >1M cycles/byte | >1M cycles/byte | >1M cycles/byte | >1M cycles/byte | >1M cycles/byte | >1M cycles/byte |
| Operating Temperature | -40C to +85C (Industrial) | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C |
Key Differentiators
- Widest VCC range in Microchip 24XX256 family (vs 24LC256-I/SN)
- 1 MHz I2C upgrade path via same-package variant (vs 24FC256-I/SN)
- Atmel-compatible write-protect for firmware portability (vs AT24C256C-SSHL-T)
- Multi-sourced 8-SOIC footprint reduces supply risk (vs BR24L256FJ-WE2)
Design Notes
Estimated: at 400 kHz I2C with bus capacitance of 100 pF (typical for 1 EEPROM plus traces), pull-up resistors in the 2.2-4.7 kohm range on SCL and SDA provide Fast-mode compatible rise times per the Microchip 24AA256 datasheet. Place the pull-ups as close to the MCU's SCL/SDA pins as possible rather than at the EEPROM end, and verify rise time at production test by probing SCL with an oscilloscope on the first prototype.
Firmware must insert at least 5 ms delay between consecutive write operations on the 24AA256-I/SN, otherwise the internal write cycle is aborted and the previous byte may be corrupted per the Microchip 24AA256/24LC256/24FC256 datasheet. Alternatively, use ACK polling by issuing a START followed by the slave address and checking for ACK - the EEPROM returns NAK while the write cycle is in progress and ACK when ready. Do not skip this delay to 'save time' - EEPROM corruption is the most common field failure.
The 24AA256-I/SN draws 1 uA typical standby current per the Microchip datasheet, which is negligible in battery-powered designs. During read the current rises to ~1 mA peak at 400 kHz; during page write it draws ~3 mA peak for the 5 ms write duration. Ensure the host power supply can source this brief inrush without sagging, especially if multiple EEPROMs share the same VCC rail during a simultaneous multi-device write.
The SDA pin is open-drain and requires an external pull-up; do not push-pull it from the MCU. The Microchip 24AA256 datasheet specifies the SCL pin is also driven open-drain in I2C mode. Adding a 100 ohm series resistor on SDA/SCL traces longer than 50 mm helps dampen ringing on Fast-mode edges; keep EEPROM traces short and away from switching power converters to avoid coupling noise into the I2C bus.
Compliance Information
RoHS and REACH compliant per Microchip product page. Not AEC-Q100 qualified; for AEC-Q100 automotive designs use Microchip AT24CS04-MAHL-T or similar qualified parts.
