Microchip Technology AT24C256B-TH-T

Overview

AT24C256B-TH-T from Microchip Technology (formerly Atmel) is a 256 Kbit I²C-compatible serial EEPROM organized as 32,768 × 8 bits, operating across 1.8 V to 5.5 V supply, supporting up to 1 MHz clock rate at 5.0 V/2.7 V/2.5 V and 400 kHz at 1.8 V, with hardware write protection via WP pin and 64-byte page write capability - deployed in industrial sensor calibration, embedded configuration storage, and power-meter firmware retention.

For engineers reviewing the AT24C256B-TH-T datasheet, AT24C256B-TH-T pinout, AT24C256B-TH-T application, or AT24C256B-TH-T equivalent, key selection considerations include its TSSOP-8 package (8A2), NiPdAu lead finish, −40°C to +85°C industrial temperature range, 1 million write cycles endurance, and 40-year data retention - all critical for long-lifecycle industrial control and metering designs.

Technical Context

The AT24C256B-TH-T implements a two-wire I²C interface with Schmitt-triggered, noise-filtered SDA/SCL inputs, enabling robust communication in electrically noisy environments. Its internal address counter supports current-address, random-address, and sequential read modes, while the 15-bit word addressing scheme maps directly to its 32,768-word memory space.

Write operations are managed through byte-write and 64-byte page-write protocols, with self-timed internal write cycles completing in ≤5 ms. Hardware write protection is enforced by the WP pin, and device addressing uses three hardwired A0–A2 pins to support up to eight devices on a shared bus - essential for modular system architectures requiring multiple nonvolatile configuration banks.

Key Specifications

Pinout & Package

AT24C256B-TH-T is supplied in an 8-lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153 compliant, with 0.65 mm lead pitch and 4.4 mm × 3.0 mm body size - optimized for high-density PCB layouts and reflow-compatible assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT24C256B-TH-T, M24256-BWMN6TP extends temperature range and ESD tolerance for harsher environments, while BR24G256FJ-3GE2 reduces standby current for battery longevity - both retain identical TSSOP-8 footprint and I²C register compatibility, enabling seamless qualification reuse.

Availability

AT24C256B-TH-T is available at Aetrix Electronics and suitable for industrial sensor calibration, smart energy metering, and PLC configuration storage requiring stable component supply across multi-year production programs.

Supply support for AT24C256B-TH-T 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 acquired Atmel in 2016 and maintains full product support, documentation, and manufacturing continuity for the AT24Cxx EEPROM family.

The AT24C256B-TH-T belongs to Microchip's serial EEPROM product line, engineered for reliable, low-voltage nonvolatile storage in industrial automation, energy infrastructure, and medical instrumentation where data integrity and long-term retention are mission-critical.

FAQ

What is the maximum I²C clock frequency supported by the AT24C256B-TH-T?

The AT24C256B-TH-T supports up to 1 MHz I²C clock frequency when operated at VCC ≥ 2.5 V (e.g., 3.3 V or 5.0 V), and 400 kHz at 1.8 V. These speeds are guaranteed across the full −40°C to +85°C industrial temperature range and require proper bus pull-up sizing (e.g., 2.2 kΩ for 1 MHz on 100 pF bus capacitance). The AT24C256B-TH-T does not support FM+ (1 MHz+) or high-speed mode beyond these specifications.

Does the AT24C256B-TH-T require external pull-up resistors on SDA and SCL lines?

Yes, the AT24C256B-TH-T requires external pull-up resistors on both SDA and SCL lines because its I²C interface uses open-drain outputs. Typical values range from 2.2 kΩ (for 1 MHz operation on low-capacitance buses) to 10 kΩ (for 400 kHz on longer traces); the exact value depends on bus capacitance, VCC, and desired rise time. The AT24C256B-TH-T itself contains no internal pull-ups.

How does the write protect (WP) pin function on the AT24C256B-TH-T?

The WP pin on the AT24C256B-TH-T is an active-high hardware lock: when tied to VCC, it disables all write operations (byte, page, and write-enable commands) to the entire memory array. When grounded, normal writes are permitted. Floating WP defaults to GND internally, but Microchip recommends hardwiring it to avoid noise-induced protection failures - a design requirement explicitly documented for the AT24C256B-TH-T.

What package type and lead finish does the AT24C256B-TH-T use?

The AT24C256B-TH-T uses an 8-lead Thin Shrink Small Outline Package (TSSOP), designated as package code 8A2 per Microchip's ordering guide, with NiPdAu (nickel-palladium-gold) lead finish - a RoHS-compliant, lead-free termination optimized for solderability and corrosion resistance in industrial environments.

Can the AT24C256B-TH-T be used in a 1.8 V-only system without level shifting?

Yes, the AT24C256B-TH-T is fully specified for 1.8 V operation: it supports 400 kHz I²C communication, guarantees 1 µA max standby current, and meets all DC/AC timing parameters at VCC = 1.8 V. It interfaces directly with 1.8 V microcontrollers (e.g., MSP430FRxx, STM32L4) without level shifters, provided the host's I²C pins are 1.8 V tolerant and pull-ups are referenced to 1.8 V.