STMicroelectronics M95256-DFDW6TP

Overview

M95256-DFDW6TP from STMicroelectronics is a 256-Kbit serial SPI EEPROM with 1.7 V to 5.5 V single-supply operation, 64-byte page size, Identification page (lockable), and 20 MHz clock support. It delivers >4 million write cycles and >200-year data retention, deployed in industrial sensor nodes for firmware parameter storage and calibration data logging.

For engineers reviewing the M95256-DFDW6TP datasheet, M95256-DFDW6TP pinout, M95256-DFDW6TP application, or M95256-DFDW6TP equivalent, key selection criteria include low-voltage compatibility (1.7 V min), hardware/software write protection granularity (quarter/half/whole array), Identification page lockability, and ECOPACK2-compliant WLCSP8 packaging for space-constrained PCBs.

Technical Context

The device implements a standard SPI interface compliant with CPOL=0/CPHA=0 and CPOL=1/CPHA=1 modes, with data latched on C's rising edge and output on falling edge. It integrates an internal high-voltage generator and ECC logic for reliable byte/page writes.

Its Status register (SRWD, BP1/BP0, WEL, WIP) enables dual-layer protection: software-configurable block locking via WRSR and hardware-enforced SRWD+WP pin control. The dedicated 64-byte Identification page supports permanent read-only locking after programming.

Key Specifications

Pinout & Package

Package: WLSCP8 (1.289 × 1.376 mm), ECOPACK2-compliant wafer-level chip-scale package with bottom-side bumps - optimized for ultra-compact portable and wearable designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT25DF256A-SSH-T and M95256-DWDW6TP, M95256-DFDW6TP uniquely combines sub-2 V operation, lockable Identification page, and 1.29 mm × 1.38 mm WLCSP packaging - making it optimal for battery-powered, security-aware, space-constrained designs.

Availability

M95256-DFDW6TP is available at Aetrix Electronics and suitable for industrial sensor calibration, medical device configuration, automotive body control, and smart meter firmware storage requiring stable component supply across extended product lifecycles.

Supply support for M95256-DFDW6TP 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, designing and manufacturing microcontrollers, power ICs, sensors, and memory solutions for industrial, automotive, and consumer markets.

The M95256 series belongs to ST's serial EEPROM product line, engineered specifically for robust, low-voltage, secure nonvolatile storage in resource-constrained embedded systems with stringent reliability and longevity requirements.

FAQ

What is the purpose of the Identification page in M95256-DFDW6TP?

The Identification page is a dedicated 64-byte memory region used to store sensitive application data such as device serial numbers, cryptographic keys, or calibration constants. It can be permanently locked in read-only mode using the LID instruction, preventing any further writes even if the Write Enable Latch is set - ensuring immutable identity and security-critical parameters.

How does the HOLD pin function during SPI communication?

The HOLD pin pauses ongoing SPI transactions without deselecting the device or resetting internal state. When driven low while Chip Select (S) is active, Serial Data Output (Q) goes high-impedance and Clock (C)/Data (D) become don't-care. This allows the host MCU to service time-critical interrupts and resume the exact same transaction upon releasing HOLD - preserving full command context and address pointer.

Can M95256-DFDW6TP operate reliably at 1.7 V across its full temperature range?

Yes - the M95256-DF variant is fully specified for 1.7 V to 5.5 V operation across −40 °C to +85 °C. All AC timing parameters (including 5 ms max write time), DC characteristics (VIH/VIL thresholds), and functional behavior (Status register reads, Identification page access) are guaranteed at 1.7 V min under worst-case temperature conditions per DS4712 Rev 22.

What happens if the Write Protect (W) pin is left floating?

The W pin must be actively driven high or low; floating is undefined and may cause erratic Status register protection behavior. If W is unconnected, internal leakage could allow SRWD-controlled hardware protection to activate unpredictably. ST recommends tying W to VCC (for default unlocked mode) or VSS (for default locked mode) via a pull-up/down resistor - never leaving it open.