What this MCU is and where it fits
The STM32L431RBI3 is a 32-bit ARM Cortex-M4 single-core microcontroller from the STM32L4 ultra-low-power series, clocked at 80 MHz. It carries 128 KB of Flash program memory and 64 KB of SRAM, with 52 general-purpose I/Os brought out to a 64-ball UFBGA package measuring 5x5 mm. The part includes a 12-bit ADC with 16 channels and a 12-bit DAC with 2 channels, plus a full set of connectivity interfaces: CAN, I²C, SPI, UART/USART, IrDA, LIN, QSPI, SAI, SWPMI, and MMC/SD. On-chip peripherals cover brown-out detect/reset, DMA, PWM, and a watchdog timer. The operating temperature range of -40 to 85 °C suits it for industrial control, sensor nodes, and outdoor telecom equipment where the enclosure sees seasonal temperature swings.
80 MHz Cortex-M4 — what the speed rating means for your loop
The 80 MHz core clock on this ARM Cortex-M4 with single-precision FPU provides headroom for a real-time control loop or sensor-fusion algorithm. The 64 KB SRAM is the hard limit for data buffers and stack.
Lifecycle and sourcing reality
The lifecycle stage for this part is recorded as EOL hot, meaning the manufacturer has announced end-of-life and the last-time-buy window is closing. If you have an active BOM line using the STM32L431RBI3, secure final production quantities or qualify a replacement.