Microchip Technology AT24C128B-TH-T

Overview

AT24C128B-TH-T from Microchip Technology (formerly Atmel) is a 128 Kbit (16,384 × 8) two-wire serial EEPROM with 1.8 V to 5.5 V operation, 64-byte page write capability, and hardware write protection via the WP pin. It supports up to 1 MHz I²C communication at 5.5 V and 400 kHz at 1.8 V, and is used in industrial control systems for parameter storage, calibration data retention, and firmware configuration backup.

For engineers reviewing the AT24C128B-TH-T datasheet, AT24C128B-TH-T pinout, AT24C128B-TH-T application, or AT24C128B-TH-T equivalent, key selection criteria include its TSSOP-8 package, 1.8–5.5 V supply range, 40-year data retention, 1 million write cycles, and compatibility with standard I²C bus timing and addressing protocols.

Technical Context

The AT24C128B-TH-T implements a standard two-wire (I²C-compatible) serial interface with Schmitt-triggered, noise-filtered SDA and SCL inputs. Its internal architecture includes a 14-bit address counter, 256-page memory organization (64 bytes/page), and a dedicated write-protection logic block tied to the WP pin.

It uses an open-drain bidirectional SDA line with wire-OR capability, supports cascaded multi-device bus configurations (up to eight devices via A2–A0 address pins), and features self-timed internal write cycles with acknowledge polling support - enabling host microcontrollers to verify completion without fixed delay timing.

Key Specifications

Pinout & Package

AT24C128B-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 3.0 mm × 4.4 mm body size. Pin 1 is marked by a dot in the top-left corner.

Key Features

Applications

Equivalent & Alternatives

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

Compared with M24128-BRMC-TR and R1EX24128ASAS0I, the AT24C128B-TH-T provides the widest voltage range (1.8–5.5 V) and highest I²C speed at full 5.5 V, making it ideal for mixed-voltage systems and high-throughput configuration loading - while retaining identical pinout and command set for drop-in replacement in most existing designs.

Availability

AT24C128B-TH-T is available at Aetrix Electronics and suitable for industrial sensor calibration, medical device configuration, and automotive body control module applications requiring stable component supply across multi-year production cycles.

Supply support for AT24C128B-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 now manufactures and supports the AT24C128B-TH-T as part of its broad serial EEPROM portfolio.

This device belongs to the AT24Cxx family of I²C-compatible EEPROMs designed specifically for reliable, low-power nonvolatile data storage in space-constrained embedded systems across industrial, medical, and automotive markets.

FAQ

What is the maximum I²C clock frequency supported by the AT24C128B-TH-T?

The AT24C128B-TH-T supports up to 1 MHz I²C clock frequency when operated at VCC = 5.5 V, and 400 kHz at VCC = 1.8 V. These limits are defined in the AC characteristics table and reflect guaranteed timing margins across the full industrial temperature range (−40°C to +85°C). The AT24C128B-TH-T does not support 1 MHz operation below 2.5 V.

Does the AT24C128B-TH-T require external pull-up resistors on SDA and SCL lines?

Yes, the AT24C128B-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 to 10 kΩ depending on bus capacitance and desired rise time; Microchip recommends 4.7 kΩ for standard 100 kHz operation with ≤400 pF total bus capacitance. The AT24C128B-TH-T itself does not integrate internal pull-ups.

How many devices can share the same I²C bus with the AT24C128B-TH-T?

Up to eight AT24C128B-TH-T devices can share a single I²C bus using hardware address pins A2, A1, and A0. Each combination of hardwired GND/VCC states generates a unique 7-bit slave address (1010xxx), allowing individual addressing without software arbitration. Floating address pins default to GND but Microchip advises explicit termination to prevent unintended address collisions.

What is the function of the WP pin on the AT24C128B-TH-T?

The WP (Write Protect) pin on the AT24C128B-TH-T is an active-high hardware lock that disables all write operations - including byte, page, and sequential writes - when driven to VCC. When tied to GND or left floating (internally pulled down), full read/write access is enabled. Microchip recommends using a 10 kΩ or lower pull-down resistor for robust operation in noisy environments. The AT24C128B-TH-T does not support software-only write protection without WP assertion.

What package type is used for the AT24C128B-TH-T?

The AT24C128B-TH-T uses an 8-lead Thin Shrink Small Outline Package (TSSOP) with 0.65 mm lead pitch and 3.0 mm × 4.4 mm body dimensions, compliant with JEDEC MO-153 standard. This surface-mount package features gull-wing leads and is optimized for automated PCB assembly. The "TH" in the part number explicitly denotes the TSSOP variant, distinguishing it from SOIC (SH), PDIP (PU), or dBGA2 (U2) versions of the same die.