Adafruit MB85RS4MT SPI FRAM Breakout - 4Mbit 512KB

Overview

This breakout is built around the Fujitsu MB85RS4MT, a high-performance 4-Mbit (512 KB) SPI FRAM designed for applications that demand fast, byte-addressable, non-volatile memory with extreme endurance.

The MB85RS4MT behaves like SRAM at the interface level — instantaneous reads and writes with no erase cycles, no page boundaries, and no write delays — while retaining data without power. It supports SPI clock rates up to 40 MHz, making it well-suited for high-speed data logging, buffering, counters, and state storage where Flash or EEPROM introduce latency and wear concerns.

With a guaranteed 10¹³ write cycles per byte and data retention rated up to 95 years at room temperature, this FRAM is ideal for systems with frequent updates or unreliable power. Typical use cases include energy meters, industrial sensors, robotics, and low-power embedded systems where data integrity is critical.

The breakout includes onboard 3.3 V regulation and logic-level shifting, allowing direct use with 3.3 V or 5 V microcontrollers. It is fully assembled, breadboard-friendly, and ships with standard 0.1″ header pins for quick integration.

Specification

Pinout