STMicroelectronics M24256X-FCU6T/VF

Overview

M24256X-FCU6T/VF from STMicroelectronics is a 256-Kbit I²C-compatible EEPROM organized as 32 K × 8 bits, implemented in 4-ball WLCSP (ECOPACK2) packaging. It operates from 1.6 V to 3.6 V, supports I²C bus speeds up to 1 MHz (Fast-mode Plus), and delivers >4 million write cycles with >200-year data retention. Its configurable device address (CDA) and software write protection (SWP) registers enable flexible multi-device addressing and selective memory locking - used in space-constrained IoT sensor nodes for calibration storage.

For engineers reviewing the M24256X-FCU6T/VF datasheet, M24256X-FCU6T/VF pinout, M24256X-FCU6T/VF application, or M24256X-FCU6T/VF equivalent, key selection criteria include WLCSP-4 footprint compatibility, 1.6–3.6 V single-supply operation, software-configurable I²C address (3-bit CDA), page-write capability (64-byte pages), and identification page lockability for secure parameter storage.

Technical Context

The M24256X-FCU6T/VF implements an I²C slave interface with open-drain SDA and input-only SCL, requiring external pull-up resistors. Its internal architecture includes dedicated ECC logic per 4-byte group, enabling single-bit error correction during reads without protocol overhead.

It integrates two non-volatile configuration registers: an 8-bit CDA register (bits C2–C0 define 8 possible I²C addresses; DAL bit permanently locks it), and an 8-bit SWP register (WPA + BP1/BP0 define quarter/half/¾/full memory protection; WPL bit irreversibly freezes protection settings).

Key Specifications

Pinout & Package

Package: WLCSP 4-ball (ECOPACK2), unsawn wafer format - each die individually tested and marked on bump side; footprint optimized for <1 mm² board area in wearable and implantable devices.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar I²C EEPROM applications.

Compared with AT24C256C-SSHL-T and BR24G256FJ-3GE2, the M24256X-FCU6T/VF uniquely combines WLCSP-4 footprint, software-configurable addressing, and lockable identification page - enabling higher integration density and field-updatable security in constrained-edge systems.

Availability

M24256X-FCU6T/VF is available at Aetrix Electronics and suitable for medical wearables, automotive cabin sensors, industrial edge gateways, and smart home actuators requiring stable component supply across extended product lifecycles.

Supply support for M24256X-FCU6T/VF 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, specializing in microcontrollers, power ICs, sensors, and memory solutions for industrial, automotive, and consumer markets.

The M24256X-F series targets space-constrained, low-power embedded systems requiring robust, configurable non-volatile storage - emphasizing software-defined addressing, secure parameter locking, and extended reliability under thermal stress.

FAQ

What is the function of the DAL bit in the CDA register?

The DAL (Device Address Lock) bit is bit 0 of the configurable device address register. When set to 1, it permanently freezes the C2–C0 address bits and DAL itself, preventing further modification. This irreversible action ensures the I²C address remains fixed after final configuration - critical for production firmware stability and avoiding bus conflicts in deployed systems.

How does the identification page differ from main memory array access?

The identification page is a dedicated 64-byte region accessed using device type identifier 1011b and specific address encoding (A10 = 0). Unlike main memory, it supports a permanent lock command: once locked, write attempts return NoACK and data is discarded. This makes it ideal for storing immutable identifiers or cryptographic keys that must survive field firmware updates.

Can the M24256X-FCU6T/VF operate at 1.6 V across its full temperature range?

No. The datasheet specifies 1.6 V operation only under restricted conditions - specifically, I²C clock frequency must be limited to ≤400 kHz, and ambient temperature must remain within −40 °C to +70 °C. Full 1 MHz operation and extended +85 °C support require VCC ≥ 1.65 V, as confirmed in Table 9 of DS12380 Rev 2.

What happens during a page write that crosses a 64-byte boundary?

When a page write exceeds the current 64-byte page boundary, the device performs automatic "roll-over": remaining bytes wrap to the start of the same page (address 0x0000 within that page), not the next page. This behavior is deterministic and documented in Section 6.1.2 - ensuring predictable data placement without host-side address management overhead.