STMicroelectronics STM32L431RBI3

Overview

STM32L431RBI3 from STMicroelectronics is an ultra-low-power Arm® Cortex®-M4 32-bit MCU with FPU, operating up to 80 MHz (100 DMIPS), featuring 256 KB Flash, 64 KB SRAM, and integrated analog peripherals including 12-bit ADC (5 Msps), dual 12-bit DACs, op-amp with PGA, and two ultra-low-power comparators - deployed in battery-powered IoT sensor nodes requiring sub-µA standby operation and RTC-backed wake-up.

For engineers reviewing the STM32L431RBI3 datasheet, STM32L431RBI3 pinout, STM32L431RBI3 application, or STM32L431RBI3 equivalent, key selection criteria include verified 280 nA Standby-with-RTC current, 4 µs Stop-mode wakeup latency, FlexPowerControl architecture enabling dynamic voltage scaling, and UFBGA64 (5×5 mm) package compatibility with high-density PCB layouts.

Technical Context

The STM32L431RBI3 implements an Adaptive Real-time Accelerator (ART Accelerator™) for zero-wait-state execution from Flash at 80 MHz, paired with a Memory Protection Unit (MPU) and interconnect matrix for deterministic peripheral arbitration. Its power architecture integrates dual regulators supporting multiple voltage scaling modes (VOS0–VOS3) and dedicated low-power domains for RTC, backup registers, and LPTIMs.

Clock management includes dual PLLs (system + audio/ADC), auto-trimmed MSI (100 kHz–48 MHz, ±0.25%), HSE (4–48 MHz), LSE (32.768 kHz), and HSI48 for USB/SAI timing - all configurable via RCC registers without external components. Analog subsystems operate on independent supplies (VDDA/VREF+), enabling simultaneous high-precision sensing and digital processing.

Key Specifications

Pinout & Package

UFBGA64 package with 0.5 mm ball pitch, 5×5 mm body size, and 64 I/O terminals. Designed for automated assembly and thermal performance in space-constrained applications.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ultra-low-power MCU applications.

Compared with STM32L432KBU3, the STM32L431RBI3 delivers CAN and SAI for industrial networking and audio edge processing; versus STM32L476RGT6, it achieves 60% lower Stop 2 current at the cost of reduced Flash and no second SAI - making it optimal for long-life, sensor-first deployments.

Availability

STM32L431RBI3 is available at Aetrix Electronics and suitable for smart utility metering, wearable health monitors, industrial predictive maintenance sensors, and asset tracking beacons requiring stable component supply across multi-year production cycles.

Supply support for STM32L431RBI3 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, designing and manufacturing microcontrollers, power management ICs, MEMS, and automotive-grade components since 1987.

The STM32L4 series targets ultra-low-power embedded applications demanding extended battery life, robust security, and rich analog integration - optimized for IoT endpoints, portable medical devices, and energy-harvesting systems.

FAQ

What is the maximum operating frequency and corresponding DMIPS rating of the STM32L431RBI3?

The STM32L431RBI3 operates at up to 80 MHz with an Arm Cortex-M4 core featuring FPU and ART Accelerator™, delivering 100 DMIPS (1.25 DMIPS/MHz per Dhrystone 2.1). This performance level is sustained across the full temperature range (–40 °C to +105 °C) when VOS0 voltage scaling is active and Flash prefetch is enabled.

Does the STM32L431RBI3 support hardware encryption acceleration?

No, the STM32L431RBI3 does not integrate a dedicated cryptographic accelerator (e.g., AES, PKA, or HASH). It relies on software libraries (STM32CubeL4 Crypto package) for encryption operations. For hardware-accelerated crypto, consider the STM32L4+ series (e.g., STM32L4R5) which includes AES-128/256 and SHA-256 engines.

What are the supported debug interfaces and required pins?

The STM32L431RBI3 supports Serial Wire Debug (SWD) using SWCLK and SWDIO pins (PA14/PA13), and full JTAG via TMS/TCK/TDI/TDO/TRESET (JTMS/JTCK/JTDI/JTDO/NRST). SWD is recommended for minimal footprint; JTAG requires five pins but enables Embedded Trace Macrocell™ (ETM) visibility for deep code profiling.

Can the internal 32 kHz RC oscillator (LSI) be used as the RTC clock source?

Yes, the LSI (37 kHz ±5%) can drive the RTC, but ST recommends the 32.768 kHz LSE crystal for calendar accuracy (±20 ppm typical). LSI-based RTC drifts ~100–200 ppm/day, limiting use to non-calendar applications like timeout counters or coarse scheduling where absolute timekeeping is not required.