STMicroelectronics M93C66-RMC6TG

Overview

M93C66-RMC6TG from STMicroelectronics is a 4-Kbit serial EEPROM with MICROWIRE™ interface, configurable as 512 × 8-bit or 256 × 16-bit memory, operating from 1.8 V to 5.5 V supply and supporting up to 2 MHz clock frequency. It delivers fast 5 ms byte/page write cycles, 4 million write endurance at 25°C, and 200-year data retention - deployed in industrial control modules for parameter storage and calibration data backup.

For engineers reviewing the M93C66-RMC6TG datasheet, M93C66-RMC6TG pinout, M93C66-RMC6TG application, or M93C66-RMC6TG equivalent, key selection criteria include its dual x8/x16 organization flexibility, READY/BUSY signaling during programming, enhanced ESD protection (4000 V HBM), SO8N/TSSOP8/UFDFPN8 package options, and compatibility with legacy MICROWIRE™-based microcontrollers in space-constrained embedded systems.

Technical Context

The M93C66-RMC6TG implements a static CMOS-based serial EEPROM architecture with on-chip clock pulse counter for noise immunity and automatic erase-before-write logic. Its ORG pin selects between byte-wide (x8) and word-wide (x16) memory mapping, enabling flexible data alignment without external address decoding.

It uses a three-wire MICROWIRE™ bus (S, C, D/Q) with chip-select–driven instruction framing, supports sequential read with auto-incremented addressing, and provides READY/BUSY status via Q pin during internal write/erase cycles - eliminating need for fixed delay timing in host firmware.

Key Specifications

Pinout & Package

Package: SO8N (150 mil width), RoHS-compliant ECOPACK2.

Key Features

Applications

Equivalent & Alternatives

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

Compared with M93C66-WMC6TG, the R-version adds 1.8 V operation and tighter low-VCC timing specs; versus AT25040B, it retains native MICROWIRE™ protocol and hardware-configurable x8/x16 organization - critical for deterministic timing and minimal MCU resource usage in legacy industrial controllers.

Availability

M93C66-RMC6TG is available at Aetrix Electronics and suitable for industrial sensor calibration, medical device configuration storage, and automotive body control modules requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for M93C66-RMC6TG 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 analog, microcontroller, power, and memory solutions for industrial, automotive, and consumer markets.

The M93C66-RMC6TG belongs to ST's legacy MICROWIRE™ EEPROM product line, engineered specifically for cost-sensitive, space-constrained embedded systems requiring simple, robust, and low-pin-count nonvolatile memory with guaranteed long-term data integrity.

FAQ

What is the function of the ORG pin on the M93C66-RMC6TG?

The ORG pin configures memory organization: tied to VSS, it selects x8 mode (512 bytes); left open or tied to VCC, it selects x16 mode (256 words). This hardware-selectable mode determines address width and data bus alignment, eliminating software bit-packing overhead. The pin must be statically set before any memory access and held stable during operation to avoid undefined behavior.

Does the M93C66-RMC6TG require an external pull-up resistor on the Q pin?

No external pull-up is required on Q. During READ, Q actively drives data; during programming, it drives LOW for BUSY or HIGH for READY. When deselected (S low), Q enters high-impedance state. A pull-up would conflict with active drive and is unnecessary - unlike open-drain interfaces, this is a push-pull output with built-in status signaling.

How does the clock pulse counter protect against noise-induced write errors?

The on-chip counter validates the exact number of clock edges received from start bit to S falling edge. If the count mismatches the expected value for the issued instruction (e.g., 20 cycles for WRITE in x8 mode), the command is aborted and memory remains unmodified. This prevents bit-shift corruption from EMI or ground bounce - a hardware-level safeguard not reliant on host-side error checking.

Can the M93C66-RMC6TG be used with modern SPI-capable microcontrollers?

Yes, but only via bit-banged GPIO emulation of MICROWIRE™ timing - it is not SPI-compatible. MICROWIRE™ uses separate D (input) and Q (output) lines with strict start-bit framing, whereas SPI shares MOSI/MISO. Direct SPI peripheral connection will fail. Firmware must implement precise S/C/D/Q timing per DS1077 Rev 20, including tSLSH setup and tSLCH hold requirements.