STMicroelectronics M95640-WMN6P

Overview

M95640-WMN6P from STMicroelectronics is a 64-Kbit serial SPI bus EEPROM organized as 8192 × 8 bits, operating from 2.5 V to 5.5 V supply over –40 °C to +85 °C. It supports up to 20 MHz clock frequency, delivers byte/page write in ≤5 ms (typ. 3.4 ms), and includes a 32-byte lockable identification page for secure parameter storage - used in industrial control firmware storage and embedded configuration retention.

For engineers reviewing the M95640-WMN6P datasheet, M95640-WMN6P pinout, M95640-WMN6P application, or M95640-WMN6P equivalent, key selection considerations include its SO8 (ECOPACK2) package, hardware/software write protection architecture, 4M+ write endurance, and 200-year data retention - critical for long-lifecycle IoT edge nodes and automotive body control modules.

Technical Context

The device implements a standard SPI interface with CPOL/CPHA = (0,0) or (1,1) compatibility, using dedicated S (chip select), C (clock), D (data in), Q (data out), W (write protect), and HOLD pins. Internal logic includes a status register with non-volatile BP1/BP0 bits for quarter/half/full memory block protection and SRWD bit enabling hardware-locked status register writes when W is low.

It integrates a high-voltage generator and sequencer for EEPROM programming, Schmitt-trigger inputs for noise immunity, and on-chip power-on reset (POR) that prevents spurious writes during power ramp-up. The identification page (32 bytes) is accessible only via RDID/WRID instructions and can be permanently locked in read-only mode via LID instruction.

Key Specifications

Pinout & Package

Package: SO8 (ECOPACK2), 150 mil width, RoHS-compliant surface-mount package with standard 1.27 mm pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT25640B-MAU-Y and BR24G64FJ-3GE2, M95640-WMN6P uniquely combines SPI speed (20 MHz), hardware-enforced ID page locking, and dual-layer write protection - making it optimal for safety-critical, field-upgradable embedded systems requiring both performance and security.

Availability

M95640-WMN6P is available at Aetrix Electronics and suitable for industrial automation, automotive electronics, and medical device manufacturing requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant sourcing.

Supply support for M95640-WMN6P 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, designing and manufacturing microcontrollers, power ICs, sensors, and memory solutions for industrial, automotive, and consumer markets.

M95640-WMN6P belongs to ST's serial EEPROM product line, engineered specifically for robust, low-power, high-reliability non-volatile storage in harsh environments - emphasizing data integrity, security, and long-term parametric stability.

FAQ

What is the function of the HOLD pin on M95640-WMN6P?

The HOLD pin pauses ongoing SPI communication without deselecting the device or resetting internal state. When driven low while chip select (S) is active, Q goes high-impedance and D/C are ignored, allowing the host MCU to service higher-priority interrupts. Communication resumes on HOLD release, preserving clock phase alignment - essential for deterministic real-time systems.

How does the identification page differ from main memory?

The identification page is a separate 32-byte memory region accessible only via RDID/WRID instructions - not through standard READ/WRITE commands. It supports permanent read-only locking via the LID instruction, and its contents survive full memory erase. This makes it ideal for storing immutable device identifiers, cryptographic keys, or calibration certificates that must resist accidental or malicious overwrite.

Can M95640-WMN6P be used with a 1.8 V microcontroller?

No - M95640-WMN6P is the 2.5–5.5 V variant ('W' suffix). For 1.8 V operation, ST offers M95640-R (1.8–5.5 V) or M95640-DF (1.7–5.5 V). Using M95640-WMN6P with a 1.8 V host violates V_IL/V_IH thresholds and risks unreliable communication or damage due to insufficient noise margin on input pins.

What happens if the W pin is left floating?

Leaving W floating violates the absolute maximum ratings and may cause unpredictable behavior: the SRWD bit could inadvertently enable hardware protection, locking the status register and blocking future BP1/BP0 updates. ST specifies W must be actively driven high or low - typically pulled high via 10 kΩ resistor unless hardware write protection is intentionally enabled.