What this MCU brings to the board
The STM32L431KBU6TR is an STMicroelectronics 32-bit ARM Cortex-M4 MCU clocked at 80 MHz, with 128 KB of Flash and 64 KB of SRAM. It sits in the STM32L4 ultra-low-power series, designed for applications where active current and wake-up latency matter — think battery-operated sensors, portable medical gear, or field instruments that run on a coin cell for months. The 26 I/O lines and a peripheral set including CAN, I²C, SPI, UART, and a 12-bit ADC with 10 channels give it the connectivity to handle mixed-signal control loops without an external companion chip.
80 MHz Cortex-M4 — what that means for your loop
The 80 MHz core with single-cycle multiply and a hardware FPU handles sensor fusion or PID loops without loading the CPU.
Package and temperature grade
Housed in a 32-lead UFQFPN with exposed pad, 5×5 mm footprint. That pad needs a thermal via under the die to pull heat into the ground plane — skip it and the junction temp climbs faster than the -40 to 85 °C rating suggests. The industrial temperature range covers outdoor telecom cabinets, engine-bay-adjacent controllers, and factory-floor enclosures without active cooling.