STMicroelectronics M93S56-WMN6P

Overview

M93S56-WMN6P from STMicroelectronics is a 2 Kbit (128 × 16-bit) serial EEPROM with MICROWIRE bus interface, user-configurable write protection, and OTP-locked protection register. It operates from 2.5 V to 5.5 V, supports up to 2 MHz clock, delivers ≤5 ms page/byte write time, and guarantees >4 million write cycles with >200-year data retention at +85 °C - used in industrial sensor calibration storage and embedded system configuration backup.

For engineers reviewing the M93S56-WMN6P datasheet, M93S56-WMN6P pinout, M93S56-WMN6P application, or M93S56-WMN6P equivalent, key selection criteria include its 8-pin SO8 (150 mil) ECOPACK®2 package, PRE/W-controlled protection hierarchy, synchronous MICROWIRE timing compliance, and -40 °C to +85 °C industrial temperature grade.

Technical Context

The M93S56-W implements a synchronous serial MICROWIRE interface with strict 8-bit op-code + 8-bit address + 16-bit data framing, where all instructions are validated by an on-chip clock pulse counter to reject noise-induced bit misalignment. It uses static CMOS design enabling zero-Hz operation and features internal self-timed write cycles with Ready/Busy indication via Q pin during programming.

Memory organization is fixed at 128 words × 16 bits, with page size = 4 words (64 bits), and protection granularity controlled by a dedicated 8-bit Protection Register accessible only when PRE is asserted high. The OTP bit permanently locks the register after first programming, preventing runtime reconfiguration.

Key Specifications

Pinout & Package

Package: SO8 (MN), 8-lead plastic small outline, 150 mil body width, ECOPACK®2 compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AT25020B-SSHL-T and M95256-WMN6TP, the M93S56-WMN6P uniquely provides MICROWIRE-native operation with hardware-enforced, OTP-locked protection - essential for applications requiring certified tamper resistance and legacy bus compatibility.

Availability

M93S56-WMN6P is available at Aetrix Electronics and suitable for industrial sensor calibration storage, embedded system configuration backup, and power meter firmware parameter storage requiring stable component supply and long-term lifecycle support.

Supply support for M93S56-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 products for industrial, automotive, and consumer markets.

The M93S56-WMN6P belongs to ST's legacy serial EEPROM product line, engineered specifically for MICROWIRE-bus-based industrial control systems requiring robust, low-power, and long-life nonvolatile storage with hardware-level write protection.

FAQ

What is the function of the PRE pin on the M93S56-WMN6P?

The PRE (Protection Register Enable) pin must be driven high to access the Protection Register via PRREAD, PRWRITE, or PRCLEAR instructions. When PRE is low, all protection register operations are blocked - this prevents accidental modification of write-protection settings during normal memory access, adding a hardware gate to security-critical configuration changes.

Can the M93S56-WMN6P be used with an SPI host controller?

No - the M93S56-WMN6P implements the MICROWIRE protocol, not SPI. It requires strict 1-bit start flag + 2-bit op-code + 8-bit address + 16-bit data framing and uses separate PRE and W control lines. SPI hosts cannot natively drive its timing or instruction set; a GPIO-bit-banged MICROWIRE interface or level-shifting bridge IC would be required.

How does the Ready/Busy signal work on the Q pin?

During an internal write cycle, when Chip Select (S) is held high, the Q pin outputs logic '0' to indicate Busy. Once programming completes, Q returns to logic '1' (Ready). This synchronous status signal eliminates the need for fixed-delay polling and allows precise timing of subsequent commands without violating tW (write cycle time) specifications.

Is the OTP bit in the Protection Register field-programmable or factory-set?

The OTP (One-Time-Programmable) bit is field-programmable: it is set permanently during the first PRDS (Protection Register Disable) instruction execution. Once set, the Protection Register becomes read-only and immune to further PRWRITE commands - this enables end-users to lock calibration or security data after final system configuration, meeting industrial anti-tampering requirements.