STMicroelectronics STM32U031K6U6

Overview

STM32U031K6U6 from STMicroelectronics is an ultra-low-power 32-bit Arm® Cortex®-M0+ microcontroller operating up to 56 MHz, featuring 32-Kbyte flash memory, 12-Kbyte SRAM with hardware parity, and integrated analog peripherals including a 12-bit ADC (0.4 µs conversion), 12-bit DAC, op-amp with PGA, and ultra-low-power comparator - deployed in battery-powered IoT sensors and portable medical monitors.

For engineers reviewing the STM32U031K6U6 datasheet, STM32U031K6U6 pinout, STM32U031K6U6 application, or STM32U031K6U6 equivalent, key selection criteria include shutdown current (16 nA), VBAT mode current (130 nA with RTC), Stop 2 mode consumption (515–630 nA), 53 fast I/Os (most 5 V-tolerant), and ECOPACK2-compliant UFQFPN32 (5 × 5 mm) package compatibility.

Technical Context

The STM32U031K6U6 implements an ART Accelerator with 1-Kbyte instruction cache enabling 0-wait-state execution from flash at 56 MHz, and integrates dual voltage regulators (main and low-power) for dynamic power domain control across Run, Stop, and Standby modes. Its Cortex-M0+ core includes MPU support and deterministic NVIC interrupt handling.

Analog subsystems operate on independent supplies: VDDA (1.62–3.6 V) powers ADC/DAC/OPAMP/comparator, while VBAT (1.55–3.6 V) sustains RTC and 9×32-bit backup registers during main supply loss. The device supports batch acquisition mode (BAM) and 4 µs wake-up from Stop mode via four dedicated wake-up pins.

Key Specifications

Pinout & Package

STM32U031K6U6 is housed in a 32-pin Ultra-Fine Pitch Quad Flat No-lead (UFQFPN32) package measuring 5 × 5 mm with 0.5 mm pitch, compliant with ECOPACK2 environmental standards and optimized for reflow soldering in high-volume manufacturing.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STM32L031K6T6 and RA2E1A00JFMB, the STM32U031K6U6 delivers the lowest active and standby currents among Cortex-M0+/M0/M23 MCUs with integrated analog, while providing PSA Level 1 readiness and 5 V-tolerant I/Os essential for industrial fieldbus interoperability.

Availability

STM32U031K6U6 is available at Aetrix Electronics and suitable for wearable health monitors, smart utility meters, industrial wireless sensor nodes, and portable diagnostic devices requiring stable component supply across multi-year production cycles.

Supply support for STM32U031K6U6 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 microcontrollers, power management ICs, MEMS, and automotive semiconductors for industrial, automotive, and consumer markets.

The STM32U0 series targets ultra-low-power applications demanding <1 µA system-level sleep current, integrated analog signal chains, and PSA-certifiable security - extending battery life in always-on edge devices without sacrificing computational capability.

FAQ

What is the maximum operating frequency and corresponding power consumption in Run mode?

The STM32U031K6U6 operates at up to 56 MHz with 52 μA/MHz current draw in LDO mode. At full speed, total Run mode consumption is approximately 2.91 mA (52 μA × 56 MHz), verified under 3.3 V supply and 25 °C ambient per DS14581 Rev 2 Section 6.3. This value assumes active ART Accelerator and no peripheral clocks enabled beyond CPU core.

Does the UFQFPN32 package support reflow soldering, and what is its thermal resistance?

Yes, the UFQFPN32 (5 × 5 mm) package is qualified for standard lead-free reflow profiles (J-STD-020). Its typical junction-to-case thermal resistance (R_θJC) is 45 °C/W, measured from die to exposed pad. The exposed thermal pad must be soldered to a minimum 100 mm² copper pour with ≥4 thermal vias to maintain junction temperature ≤105 °C at 56 MHz operation.

How many I/Os are available in the UFQFPN32 variant, and which support wake-up functionality?

The STM32U031K6U6 in UFQFPN32 provides 27 general-purpose I/Os. Four of these - PA0, PA1, PA2, and PA3 - are designated as wake-up pins supporting Stop/Standby mode exit. All 27 pins are 5 V-tolerant when VDD is ≥2.0 V, enabling direct interfacing with legacy 5 V logic without level shifters.

Can the internal op-amp be used in unity-gain buffer configuration without external components?

Yes, the integrated operational amplifier supports unity-gain voltage follower mode using only internal feedback. Configuration requires setting OPAMP1_CSR.OPAEN=1 and OPAMP1_CSR.FM=0 in the OPAMP control register, with VINP connected to source signal and VOUT routed to load. No external resistors or capacitors are needed, and the 16× PGA gain range remains accessible via software-controlled internal switch matrix.