STMicroelectronics M95640-DFMC6TG

Overview

M95640-DFMC6TG from STMicroelectronics is a 64-Kbit serial SPI bus EEPROM with an additional 32-byte lockable identification page, operating from 1.7 V to 5.5 V over -40 °C to +85 °C. It delivers byte/page write in ≤5 ms (typ. 3.4 ms), supports 20 MHz clock, and features Schmitt-trigger inputs, software/hardware write protection, and >4 million write cycles - used in industrial control modules for secure parameter storage and firmware revision tracking.

For engineers reviewing the M95640-DFMC6TG datasheet, M95640-DFMC6TG pinout, M95640-DFMC6TG application, or M95640-DFMC6TG equivalent, this page provides verified functional identity, validated SO8 (ECOPACK2) package mapping, confirmed SPI interface timing (CPOL/CPHA = 0/0 or 1/1), real-world data retention (>200 years), and exact status register bit behavior (BP1/BP0/SRWD/WEL/WIP) per DS6633 Rev 21.

Technical Context

The M95640-DFMC6TG implements a dedicated SPI EEPROM controller with dual-phase clock synchronization (CPOL=0/CPHA=0 or CPOL=1/CPHA=1), internal HV generator for write cycling, and ECC-enabled sense amplifiers. Its status register includes non-volatile BP1/BP0 bits for quarter/half/full memory block protection and SRWD bit enabling hardware lock of BP/SRWD via W pin.

It integrates a 32-byte identification page accessible only via RDID/WRID/LID instructions - exclusive to the -DF variant - with permanent read-only locking capability. The HOLD pin suspends active SPI transfers without resetting internal state, and all inputs include Schmitt-trigger noise filtering compliant with 4 kV HBM ESD.

Key Specifications

Pinout & Package

Package: SO8 (ECOPACK2), 150 mil width, RoHS-compliant, surface-mount.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT25DF641A-MAU-T and BR24G64FJ-WE2, the M95640-DFMC6TG uniquely combines 1.7 V operation, lockable ID page, HOLD functionality, and 20 MHz SPI - making it the only option for secure, low-voltage, interruptible parameter storage in industrial and medical edge devices.

Availability

M95640-DFMC6TG is available at Aetrix Electronics and suitable for industrial PLCs, medical diagnostic equipment, automotive body control modules, and smart energy meters requiring stable component supply across extended temperature and voltage ranges.

Supply support for M95640-DFMC6TG 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.

The M95640 series belongs to ST's serial EEPROM product line, engineered specifically for robust, low-power, secure non-volatile storage in resource-constrained embedded systems with stringent reliability and longevity requirements.

FAQ

What is the function of the HOLD pin on M95640-DFMC6TG?

The HOLD pin pauses ongoing SPI communication without deselecting the device or resetting internal state. When driven low while chip select (S) is low, it forces Q into high-impedance and ignores D and C transitions. This enables host MCU context switching or interrupt handling mid-transfer, resuming exactly where paused upon HOLD return to high - critical for deterministic real-time systems.

How does the identification page differ from main memory in M95640-DFMC6TG?

The identification page is a separate 32-byte memory region accessible only via RDID/WRID/LID instructions - not through standard READ/WRITE. Once locked via LID, it becomes permanently read-only. Unlike main memory, it cannot be erased or overwritten, providing tamper-proof storage for calibration data, serial numbers, or cryptographic keys essential for device authentication and traceability.

Can M95640-DFMC6TG operate reliably at 1.7 V supply?

Yes - the -DF variant is fully specified down to 1.7 V across -40 °C to +85 °C, with guaranteed 20 MHz clock operation, ≤5 ms write cycles, and correct status register behavior. This is validated in DS6633 Rev 21 AC/DC parameters (VCC(min) = 1.7 V, tW(max) = 5 ms, fCLK(max) = 20 MHz), enabling direct interface with 1.8 V logic families without level shifters.

What happens when both software and hardware write protection are enabled?

When SRWD = 1 and W = low, hardware protection overrides software settings: BP1/BP0 bits become read-only, WRSR is rejected, and the status register is frozen. However, main memory writes remain governed by current BP1/BP0 values - meaning existing software protection remains active, but cannot be modified. This layered enforcement ensures configuration integrity even if firmware is compromised.