AT24C256D-SSHL-T

The AT24C256D-SSHL-T from Microchip Technology is a 256Kbit (32,768 x 8) I2C-compatible serial EEPROM with enhanced data retention of 100 years in the D revision. The device supports Standard (100kHz), Fast (400kHz), and High-Speed (1MHz) I2C modes. A 64-byte page write buffer allows efficient writing of up to 64 bytes in a single write cycle, with 5ms self-timed write completion. Schmitt-trigger inputs on SCL and SDA suppress electrical noise for reliable communication in industrial environments. Three address pins (A0, A1, A2) enable up to eight AT24C256D devices on the same I2C bus, providing up to 2Mbit of addressable memory. The hardware Write Protect (WP) pin protects the entire memory array from accidental writes. The SSHL-T suffix denotes the TSSOP-8 package with tape-and-reel packaging.

The AT24C256D-SSHL-T communicates via the I2C protocol using just two signal lines: SCL (serial clock) and SDA (serial data). The master initiates communication by sending a START condition (SDA transitions from high to low while SCL is high), followed by the device address byte. The upper 4 bits are the fixed device identifier (1010), the next 3 bits match the hardware address pins (A2, A1, A0), and the LSB is the Read/Write bit. For a write operation, the master sends two address bytes (A15-A8, A7-A0) to specify the memory location, then up to 64 data bytes. The internal address counter auto-increments within the 64-byte page boundary; if the counter reaches the page end, it wraps to the beginning of the same page (not the next page). The master sends a STOP condition to initiate the internal write cycle. During the 5ms write cycle, the device does not acknowledge any I2C communication, which can be used for polling (ACK polling) to detect write completion. For a read operation, the master first writes the address (dummy write), then sends a repeated START with the R/W bit set to read. The device outputs data bytes and the internal address counter increments across page boundaries for sequential reads. The WP pin, when tied to VCC, prevents any write operation to the entire array. Schmitt-trigger inputs on SCL and SDA provide hysteresis that rejects noise spikes below the Schmitt threshold.

• Embedded Config: 256Kbit stores multiple configuration profiles, calibration tables, and firmware parameters with 100-year retention across power cycles
• Industrial Data Log: 1MHz High-Speed mode reads logged data quickly; Schmitt-trigger inputs tolerate noisy factory environments
• السيارات: 1.7V min supply compatible with battery-cranking dips; WP pin prevents ECU parameter corruption
• IoT Devices: 8 devices on one I2C bus provides 2Mbit for firmware, keys, and device state without additional chip-select lines
• الإلكترونيات الاستهلاكية: 5V and 3.3V compatible with no external level shifters; small TSSOP-8 fits in compact consumer designs

AT24C256D-SSHL-T is a 256Kbit (32768×8) I2C EEPROM from Microchip in TSSOP-8. The AT24C512D doubles density to 512Kbit in the same package. The AT24CM01 provides 1Mbit for maximum storage. The CAT24C256WI-GT3 from onsemi offers 256Kbit with hardware write protect. The M24256 from ST provides similar 256Kbit with WC pin. The 24AA256 from Microchip offers 1.7V minimum supply for low-voltage designs. For higher endurance, FM24CL16B from Cypress provides 256Kbit FRAM with 100 trillion write cycles.