Microchip Technology AT24C256B-TH-B

Overview

AT24C256B-TH-B 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 2.5 V/5.0 V. It is used in industrial control systems for parameter storage, calibration data retention, and firmware configuration backup.

For engineers reviewing the AT24C256B-TH-B datasheet, AT24C256B-TH-B pinout, AT24C256B-TH-B application, or AT24C256B-TH-B equivalent, key selection criteria include voltage range (1.8–5.5 V), page write timing (≤5 ms), endurance (1 million cycles), data retention (40 years), and TSSOP-8 package compatibility with space-constrained PCB layouts.

Technical Context

The AT24C256B-TH-B implements a standard I²C-compatible two-wire interface with Schmitt-triggered, noise-filtered SDA and SCL inputs. Its internal address counter supports current-address, random-address, and sequential read modes, while the A0–A2 pins enable up to eight devices on a shared bus.

Write operations use either byte-write or 64-byte page-write protocols with self-timed internal erase/write cycles. Hardware write protection is enforced when WP is tied to V_CC, and acknowledge polling allows host synchronization without fixed delay timing.

Key Specifications

Pinout & Package

AT24C256B-TH-B is supplied in an 8-lead Thin Shrink Small Outline Package (TSSOP) with 0.65 mm lead pitch, 3.0 mm × 4.4 mm body, and NiPdAu lead finish - optimized for automated assembly and thermal reliability in compact industrial modules.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar serial EEPROM applications.

Compared with M24256-BWMN6TP and CAT24C256WI-GT3, the AT24C256B-TH-B offers identical functional behavior and pinout in TSSOP-8, but differs in qualification scope (industrial vs. automotive) and packaging format (bulk vs. tape-and-reel), making it optimal for cost-sensitive industrial OEMs prioritizing flexible procurement.

Availability

AT24C256B-TH-B is available at Aetrix Electronics and suitable for industrial control systems, medical instrumentation, smart energy meters, and automated test equipment requiring stable component supply and long-term lifecycle support.

Supply support for AT24C256B-TH-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 for industrial, automotive, and communications markets.

The AT24C256B-TH-B belongs to Microchip's AT24Cxx family of I²C-compatible serial EEPROMs, designed specifically for reliable, low-power, multi-voltage data storage in space-constrained embedded systems.

FAQ

What is the operating voltage range of the AT24C256B-TH-B?

The AT24C256B-TH-B operates from 1.8 V to 5.5 V, enabling direct integration with 1.8 V logic families, 3.3 V microcontrollers, and legacy 5 V systems without level translation. This wide range supports mixed-voltage board designs and simplifies power architecture in multi-rail embedded platforms. The AT24C256B-TH-B maintains full I²C functionality-including 1 MHz clock support at 2.5 V/5.0 V and 400 kHz at 1.8 V-across the entire voltage window.

Does the AT24C256B-TH-B support page write operations?

Yes, the AT24C256B-TH-B supports 64-byte page write mode, allowing up to 64 bytes to be written in a single I²C transaction with ≤5 ms internal write cycle time. This significantly improves throughput versus byte-write mode and reduces host processor overhead. Partial page writes are permitted, and the internal address counter wraps within the current 64-byte page boundary. The AT24C256B-TH-B does not auto-increment beyond the page boundary unless explicitly commanded via sequential addressing.

How is hardware write protection implemented on the AT24C256B-TH-B?

Hardware write protection on the AT24C256B-TH-B is controlled by the WP (Write Protect) pin: when WP is tied to V_CC, all write operations-including byte, page, and write-enable commands-are inhibited; when WP is grounded, full read/write access is granted. The AT24C256B-TH-B includes internal weak pull-downs on WP, but Microchip recommends hardwiring WP to a defined logic state using ≤10 kΩ resistors to prevent noise-induced failures in electrically noisy environments.

What package type is used for the AT24C256B-TH-B?

The AT24C256B-TH-B uses an 8-lead Thin Shrink Small Outline Package (TSSOP) with 3.0 mm × 4.4 mm body, 0.65 mm lead pitch, and NiPdAu lead finish. This package meets JEDEC MO-153 standards, supports fine-pitch SMT assembly, and provides superior thermal performance and moisture resistance compared to SOIC variants. The AT24C256B-TH-B's TSSOP footprint is pin-compatible with other 8-lead I²C EEPROMs in the same outline, easing layout reuse.

What is the endurance and data retention specification for the AT24C256B-TH-B?

The AT24C256B-TH-B guarantees 1,000,000 write/erase cycles and 40 years of data retention at +85°C ambient temperature. These specifications are validated per JEDEC standards and apply across the full 1.8–5.5 V supply range and −40°C to +85°C industrial temperature grade. The AT24C256B-TH-B achieves this reliability through optimized oxide thickness and charge-trapping design in its floating-gate EEPROM cell structure.