STMicroelectronics M95640-WDW6TP

Overview

M95640-WDW6TP 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 voltage over –40 °C to +85 °C ambient temperature. It features 32-byte page write capability, 5 ms typical byte/page write time, and includes a lockable 32-byte identification page for secure parameter storage. Used in industrial control modules for firmware revision tracking and calibration data retention.

For engineers reviewing the M95640-WDW6TP datasheet, M95640-WDW6TP pinout, M95640-WDW6TP application, or M95640-WDW6TP equivalent, key selection criteria include its 20 MHz SPI clock support, hardware/software write protection (W pin + BP bits), Schmitt-trigger noise immunity, ECOPACK2-compliant SO8 package, and 200-year data retention - critical for long-lifecycle embedded systems requiring field-updatable nonvolatile storage.

Technical Context

The M95640-WDW6TP implements a standard SPI interface with CPOL=0/CPHA=0 or CPOL=1/CPHA=1 mode compatibility, using dedicated S (chip select), C (clock), D (data in), Q (data out), W (write protect), and HOLD (communication pause) signals. Its internal architecture includes an HV generator, sequencer, ECC-enabled sense amplifiers, and status register with WIP, WEL, BP1/BP0, and SRWD bits.

It supports dual protection layers: software-configurable quarter/half/full memory block locking via BP bits, and hardware-enforced status register write disable when SRWD=1 and W pin is low. The identification page (32 bytes) is accessible only via RDID/WRID instructions and can be permanently locked in read-only mode using LID instruction.

Key Specifications

Pinout & Package

Package: SO8 (ECOPACK2), 150 mil width, RoHS-compliant surface-mount package with standard JEDEC MS-012AC footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT25DF041A-SSH-T and BR24G64FJ-WE2, the M95640-WDW6TP uniquely combines wide-voltage SPI operation, hardware/software write protection, and a lockable identification page - making it optimal for safety-critical, long-lifecycle, and mixed-voltage embedded systems requiring field-verifiable identity and configuration integrity.

Availability

M95640-WDW6TP is available at Aetrix Electronics and suitable for industrial PLCs, medical infusion pumps, automotive body control modules, and smart energy meters requiring stable component supply across multi-year production runs.

Supply support for M95640-WDW6TP 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 management ICs, sensors, and memory solutions for industrial, automotive, and consumer markets.

The M95640 series belongs to ST's serial EEPROM product line, engineered specifically for robust, low-power, long-retention nonvolatile storage in harsh environments - emphasizing reliability, security, and interoperability with mainstream MCU SPI peripherals.

FAQ

What is the function of the HOLD pin on M95640-WDW6TP?

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 automatically when HOLD returns high, preserving bit position and instruction context - essential for deterministic real-time systems.

How does the identification page differ from main memory?

The identification page is a dedicated 32-byte memory region accessible only via RDID/WRID instructions, separate from the main 8192-byte array. It supports permanent read-only locking via the LID instruction, and its lock status is readable via RDLS. Unlike main memory, it cannot be erased or overwritten once locked - making it ideal for storing immutable device identifiers, cryptographic keys, or regulatory certification data.

Can M95640-WDW6TP operate at 2.5 V and still achieve 20 MHz SPI speed?

Yes - the M95640-WDW6TP guarantees full 20 MHz SPI clock operation across its entire 2.5 V to 5.5 V supply range, as verified in AC timing specifications (tCLQV, tCLQX, tCLQZ). At 2.5 V, setup/hold times remain within spec due to internal voltage scaling and Schmitt-trigger input hysteresis, enabling reliable high-speed communication in battery-powered or low-voltage industrial systems without performance derating.

What happens if the W pin is left floating during operation?

The W pin must be actively driven high or low; floating violates the absolute maximum ratings and may cause undefined behavior in status register write protection. If W floats near the logic threshold, SRWD enforcement becomes unreliable, potentially allowing unintended WRSR execution or failing to lock BP bits. STMicroelectronics specifies mandatory pull-up or pull-down - typically 10 kΩ to VCC or VSS - to ensure deterministic hardware protection activation.