STMicroelectronics M34C02-WDW6T

Overview

M34C02-WDW6T from STMicroelectronics is a 2 Kbit I²C serial EEPROM designed for Serial Presence Detect (SPD) in DDR SDRAM DIMMs. It features 256 × 8-bit organization, software write-protection for the lower 128 bytes (00h–7Fh), 400 kHz I²C interface, and operates from 2.5 V to 5.5 V. Its primary role is nonvolatile storage of module configuration data including timing parameters, density, and vendor ID.

For engineers reviewing the M34C02-WDW6T datasheet, M34C02-WDW6T pinout, M34C02-WDW6T application, or M34C02-WDW6T equivalent, key selection criteria include SPD-compliant voltage range (2.5–5.5 V), guaranteed 1 million erase/write cycles, 40-year data retention, and hardware/software dual write-protection architecture for DIMM configuration integrity.

Technical Context

The device implements a two-wire I²C slave interface with fixed 4-bit device type identifiers: 1010b for memory array access and 0110b for protection register access. Chip enable inputs E0–E2 allow up to eight devices on one bus via 3-bit address decoding.

It supports byte and page write (up to 16 bytes per cycle), random/sequential read modes, automatic address incrementing, and self-timed internal programming. A Power-On Reset (POR) circuit prevents spurious writes during power ramp-up, with reset threshold below minimum operating VCC.

Key Specifications

Pinout & Package

Package: TSSOP8 (DW), 169 mil width, RoHS-compliant ECOPACK®.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT24C02C-SSHM-T and FM24C02B-G, M34C02-WDW6T uniquely combines user-configurable I²C addressing (E0–E2), hardware WC pin for unconditional write disable, and irreversible software lock - making it the only option qualified for JEDEC-compliant multi-DIMM server platforms requiring guaranteed SPD integrity.

Availability

M34C02-WDW6T is available at Aetrix Electronics and suitable for DDR2/DDR3 DIMM manufacturing, server memory module refurbishment, and industrial SO-DIMM production requiring stable component supply and long-term SPD data integrity.

Supply support for M34C02-WDW6T 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, Switzerland, specializing in microcontrollers, power management, sensors, and memory solutions for industrial, automotive, and computing markets.

M34C02-WDW6T belongs to ST's serial EEPROM product line engineered specifically for JEDEC SPD compliance in DRAM modules - emphasizing write-protection robustness, wide-voltage operation, and multi-device I²C bus scalability.

FAQ

What is the function of the WC pin on M34C02-WDW6T?

The WC (Write Control) pin is a hardware-level write enable/disable input. When driven high, it permanently disables all write operations to both memory array and protection register - overriding any software lock state. When low, writes are permitted subject to software protection settings. This dual-layer mechanism ensures SPD data cannot be altered after final programming, even if firmware attempts unauthorized writes.

Can M34C02-WDW6T be used in DDR4 modules?

No. M34C02-WDW6T is not compliant with DDR4 SPD specifications, which require 512-byte capacity (4 Kbit minimum) and extended data fields beyond JEDEC DDR2/DDR3 standards. Its 256-byte capacity and register map align exclusively with DDR2 and DDR3 UDIMM/RDIMM SPD requirements per JESD21-C and JESD21-F.

How does the software write-protection mechanism work?

Software write-protection is activated by writing a specific sequence to the Protection Register using I²C device select code 0110b. Once set, the lower 128 bytes (00h–7Fh) become permanently locked - no subsequent command or voltage cycle can unlock them. This feature is independent of WC pin state and survives power cycles, ensuring SPD configuration remains immutable after factory programming.

What package variant does M34C02-WDW6T use?

M34C02-WDW6T uses the TSSOP8 (DW) package: 8-lead Thin Shrink Small Outline with 169 mil body width, 0.65 mm lead pitch, and ECOPACK® RoHS-compliant finish. Pin 1 is marked by a dot or beveled corner; mechanical dimensions conform to ST's package drawing DW-08.