STMicroelectronics M95256-DRDW3TP/K

Overview

M95256-DRDW3TP/K from STMicroelectronics is an AEC-Q100 Grade 0 qualified 256-Kbit serial SPI EEPROM designed for automotive powertrain and body control modules. It delivers 32 Kbytes of byte-alterable memory organized in 512 × 64-byte pages, supports up to 20 MHz clock (at VCC ≥ 4.5 V), features embedded ECC logic for enhanced data integrity, and operates across extended temperature ranges up to 145 °C with VCC from 2.5 V to 5.5 V.

For engineers reviewing the M95256-DRDW3TP/K datasheet, M95256-DRDW3TP/K pinout, M95256-DRDW3TP/K application, or M95256-DRDW3TP/K equivalent, key selection criteria include automotive-grade endurance (400 k write cycles at 145 °C), programmable block write protection (1/4, 1/2, or full memory), identification page locking capability, and Schmitt-trigger noise-immune inputs for harsh ECU environments.

Technical Context

This SPI EEPROM implements CPOL=0/CPHA=0 and CPOL=1/CPHA=1 compatible protocols with input latching on rising clock edge and output shifting on falling edge. Its internal architecture includes a dedicated high-voltage generator, address/data registers, and status register with WIP/WEL/BP1-BP0/SRWD bits for real-time write state monitoring and non-volatile protection configuration.

The device integrates an Identification Page (64 bytes) that stores ST device ID and supports permanent lock via LID instruction; it also embeds ECC logic per 4-byte group to detect and correct single-bit errors during read operations, significantly improving reliability in safety-critical automotive firmware storage.

Key Specifications

Pinout & Package

TSSOP8 (DW) package: 8-lead thin shrink small outline, 3 mm × 4.4 mm body, 0.65 mm pitch, RoHS-compliant and halogen-free (ECOPACK2®).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT25DF041A-MAHN-T and BR25H256FJ-WE2, M95256-DRDW3TP/K uniquely combines Grade 0 qualification, 145 °C endurance, ECC, and lockable ID page - making it the only option for ASIL-B-compliant powertrain firmware storage requiring both longevity and security.

Availability

M95256-DRDW3TP/K is available at Aetrix Electronics and suitable for automotive powertrain control, ADAS sensor calibration, transmission management, and body electronics requiring stable component supply across extended temperature and voltage ranges.

Supply support for M95256-DRDW3TP/K 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 automotive, industrial, and power management ICs with strong vertical integration in process technology and packaging.

M95256-DRDW3TP/K belongs to ST's automotive-grade serial EEPROM product line, engineered specifically for mission-critical non-volatile storage in engine, transmission, and ADAS ECUs where reliability, security, and extended temperature operation are mandatory.

FAQ

What is the maximum operating temperature and corresponding write endurance for M95256-DRDW3TP/K?

The device is rated for continuous operation up to +145 °C ambient temperature and guarantees 400,000 write cycles at that temperature. This endurance is validated per AEC-Q100 Grade 0 test conditions and reflects actual cycling performance measured at junction temperature, not ambient alone. Endurance degrades predictably with temperature: 600 k cycles at 125 °C, 1.2 M at 85 °C, and 4 M at 25 °C.

How does the Identification Page differ from standard memory pages, and how is it secured?

The Identification Page is a dedicated 64-byte area storing ST device ID and user-configurable parameters. Unlike standard pages, it supports the RDID and WRID instructions and can be permanently locked using the LID instruction. Once locked, all subsequent WRID and LID commands are ignored, and the page becomes read-only for the device's lifetime - providing hardware-enforced immutability for vehicle identity data.

Can M95256-DRDW3TP/K operate reliably on a 3.3 V supply in automotive environments with high noise?

Yes - the device operates across 2.5 V to 5.5 V and includes Schmitt-trigger inputs on all control pins (S, C, D, HOLD, W), providing ≥1.5 V hysteresis to reject common-mode noise typical in 12 V vehicle harnesses. At 3.3 V, it supports 10 MHz SPI clocking and maintains full specification compliance for timing, endurance, and data retention across −40 °C to +145 °C.

What protection mechanisms prevent accidental writes to protected memory blocks?

Two independent layers protect memory: (1) non-volatile BP1/BP0 bits in the Status Register define protected block size (1/4, 1/2, or full array); (2) the SRWD bit, when set to 1, ties Status Register writes to the W pin state - if W is low, WRSR is discarded and BP bits cannot be modified. This dual mechanism prevents both software glitches and hardware faults from altering protection settings.