Microchip Technology 24LC128T-E/SN

Overview

24LC128T-E/SN from Microchip Technology is a 128 Kbit (16K × 8) I²C-compatible serial EEPROM with hardware write-protection, 64-byte page write buffer, and industrial-temperature operation (–40°C to +85°C). It operates from 2.5V to 5.5V, supports up to 400 kHz clock frequency, and delivers ≤1 µA standby current. Used in embedded systems for parameter storage, calibration data retention, and firmware configuration in power-constrained applications.

For engineers reviewing the 24LC128T-E/SN datasheet, 24LC128T-E/SN pinout, 24LC128T-E/SN application, or 24LC128T-E/SN equivalent, this page provides verified electrical specs, package mapping to SOIC-8 (SN), I²C timing constraints, WP-controlled write protection behavior, and real-world use cases in industrial control and sensor modules.

Technical Context

The 24LC128T-E/SN implements a two-wire I²C slave interface with Schmitt-trigger inputs on SDA/SCL for noise immunity and slope-controlled outputs to suppress ground bounce. Its internal address counter enables sequential reads across the full 128Kbit memory space, while cascading support via A0–A2 pins allows up to eight devices on one bus.

Write operations are self-timed and include byte-write and 64-byte page-write modes, with automatic wraparound handling within physical page boundaries. The WP pin samples at the Stop bit to enable or disable writes-no effect occurs if toggled mid-cycle-and endurance is rated at 1 million cycles with >200-year data retention.

Key Specifications

Pinout & Package

24LC128T-E/SN uses the 8-Lead Plastic Small Outline (SOIC-Narrow, SN) package per Microchip drawing C04-057-SN: 3.90 mm body width, 1.27 mm lead pitch, gull-wing leads. Pin 1 is marked by notch or dot; device orientation follows JEDEC MS-012 standard.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 24LC128T-E/SN, the 24AA128T-I/SN enables lower-voltage operation down to 1.7V but shares identical packaging and I²C protocol, while the AT24C128-10PU-2.7 offers equivalent functionality with minor timing differences requiring validation in high-speed or low-VCC edge cases.

Availability

24LC128T-E/SN is available at Aetrix Electronics and suitable for industrial sensor calibration, medical device configuration, and automotive body control modules requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for 24LC128T-E/SN 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 Inc. is a leading provider of microcontrollers, analog components, and memory solutions, headquartered in Chandler, Arizona, with global design and manufacturing operations.

The 24LC128T-E/SN belongs to Microchip's 24XX128 family of I²C serial EEPROMs, designed specifically for reliable, low-power nonvolatile data storage in space-constrained embedded systems where write endurance and data retention are critical.

FAQ

What is the minimum supply voltage required for 24LC128T-E/SN operation?

The 24LC128T-E/SN requires a minimum VCC of 2.5V for guaranteed operation across its full temperature range (–40°C to +85°C). Below 2.5V, the device is not specified - unlike the 24AA128 variant, which supports down to 1.7V. Operating 24LC128T-E/SN below 2.5V may result in undefined behavior or failure to acknowledge I²C commands.

How does the WP pin function on the 24LC128T-E/SN?

The WP (Write-Protect) pin on the 24LC128T-E/SN is sampled only at the Stop bit of each write command. When tied to VCC, it disables all write operations (byte and page) while permitting unlimited reads. Toggling WP during an active write cycle has no effect - protection state is latched at Stop, ensuring robustness against transient noise or power glitches.

Can multiple 24LC128T-E/SN devices share the same I²C bus?

Yes - up to eight 24LC128T-E/SN devices can be cascaded on a single I²C bus using the A0, A1, and A2 address inputs. Each device is assigned a unique 7-bit slave address (0x50–0x57) by hardwiring these pins to VSS or VCC. This enables scalable memory expansion without additional GPIO or address decoding logic.

What is the maximum page write size supported by 24LC128T-E/SN?

The 24LC128T-E/SN supports a maximum page write size of 64 bytes. Writes crossing physical page boundaries (every 64-byte aligned block: 0x0000–0x003F, 0x0040–0x007F, etc.) will wrap around within the current page rather than spill into the next. Software must enforce page alignment to avoid unintended data overwrite during multi-byte writes.

Is the 24LC128T-E/SN compatible with 1 MHz I²C clock speeds?

No - the 24LC128T-E/SN is rated for a maximum clock frequency of 400 kHz at VCC ≥2.5V. For 1 MHz operation, Microchip specifies the 24FC128 variant instead. Attempting 1 MHz communication with 24LC128T-E/SN may cause timing violations, missed ACKs, or corrupted data transfers due to insufficient setup/hold margins.