STMicroelectronics STM32U031K4U6

Overview

STM32U031K4U6 from STMicroelectronics is an ultra-low-power 32-bit Arm® Cortex®-M0+ microcontroller operating up to 56 MHz, featuring 16-Kbyte flash memory, 12-Kbyte SRAM with hardware parity, and integrated analog peripherals including a 12-bit ADC, 12-bit DAC, operational amplifier with PGA, and ultra-low-power comparator - deployed in battery-powered IoT sensor nodes requiring sub-μA standby operation.

For engineers reviewing the STM32U031K4U6 datasheet, STM32U031K4U6 pinout, STM32U031K4U6 application, or STM32U031K4U6 equivalent, key selection criteria include verified VBAT mode current (130 nA), Stop 2 mode consumption (630 nA with RTC), 53 fast I/Os (most 5 V-tolerant), and WLCSP27 package compatibility for space-constrained wearable designs.

Technical Context

The STM32U031K4U6 implements a single-stage pipeline Cortex-M0+ core with MPU, ART Accelerator enabling 0-wait-state execution from flash at 56 MHz, and adaptive clocking via MSI oscillator auto-trimmed by LSE (±0.25% accuracy). It integrates dual-regulator power management (MR/LPR) supporting six low-power modes - Shutdown (16 nA), Standby (30 nA without RTC), and Stop 2 (515–630 nA) - with four dedicated wake-up pins and 4 μs wake-up latency.

Analog subsystem includes independent VDDA supply (1.62–3.6 V), rail-to-rail comparator, 12-bit DAC with sample-and-hold, and 18-capacitive-sensing-channel support. Security features comprise Arm PSA Level 1/SESIP Level 3 candidate certification, true random number generator (NIST SP 800-90B candidate), 96-bit unique ID, and 5 passive anti-tamper pins.

Key Specifications

Pinout & Package

STM32U031K4U6 is housed in a 27-ball WLCSP (Wafer-Level Chip Scale Package) measuring 2.55 × 2.34 mm with 0.4 mm pitch, optimized for ultra-compact portable electronics. Pin assignment follows STMicroelectronics' DT71281V2 layout.

Key Features

Applications

Equivalent & Alternatives

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

Compared with STM32L011K4U6 and EFM32ZG222F32, the STM32U031K4U6 delivers superior analog integration (DAC+OPAMP+comparator), lower VBAT mode current (130 nA vs. ≥200 nA), and broader capacitive sensing support - making it optimal for compact, self-contained sensor edge nodes.

Availability

STM32U031K4U6 is available at Aetrix Electronics and suitable for smart wearables, medical diagnostic patches, industrial condition monitoring, and asset tracking beacons requiring stable component supply across long-lifecycle deployments.

Supply support for STM32U031K4U6 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, sensors, and automotive semiconductors for industrial, automotive, and consumer markets.

The STM32U0 series targets ultra-low-power embedded applications demanding sub-μA operation, robust security, and high analog integration - specifically engineered for battery-powered IoT endpoints where size, energy, and trust are non-negotiable.

FAQ

What is the minimum supply voltage for reliable operation of STM32U031K4U6?

The STM32U031K4U6 operates reliably from 1.71 V to 3.6 V on VDD. Below 1.71 V, brownout reset (BOR) activates to prevent undefined behavior; the device supports programmable BOR thresholds via option bytes, allowing design margin adjustment for aging batteries or low-voltage environments.

Does STM32U031K4U6 support in-circuit debugging without external tools?

Yes - it includes native Serial Wire Debug (SWD) interface via dedicated SWDIO and SWCLK pins. No external debugger is needed beyond a standard SWD probe (e.g., ST-LINK/V2-1); full programming, real-time variable inspection, and breakpoint control are supported directly from STM32CubeIDE without additional hardware.

Can the integrated operational amplifier drive a 10 kΩ load with rail-to-rail output?

Yes - the OPAMP supports rail-to-rail output swing and delivers ±20 mA output current. With VDD = 3.3 V and VDDA = 3.3 V, it maintains full 0–3.3 V output range into 10 kΩ loads, validated per DS14581 Section 6.3.11, making it suitable for driving external ADC references or sensor bias networks.

How many capacitive sensing channels are accessible on the WLCSP27 package?

The STM32U031K4U6 in WLCSP27 supports 3 capacitive sensing channels, mapped to PA0, PA1, and PA2 per Table 1 and Section 9.3.1 of DS14581 Rev 2. This matches its pin count limitation - larger packages (e.g., LQFP48) support up to 18 channels, but WLCSP27 retains sufficient touch capability for single-button or dual-slider interfaces.