STM32L031K6U6 ST Mainstream Arm Cortex-M0+ Ultra-Low-Power 32-bit MCU 32KB Flash 8KB SRAM EEPROM ADC UFQFPN-32

STM32L031K6U6 Product Overview

STM32L031K6U6 is a Cortex-M0+ MCU at 32 MHz, UFQFPN-32. 32 KB Flash, 8 KB SRAM, 1 KB EEPROM, 12-bit ADC (10 ch), LP timers, RTC, 1×USART, 1×SPI, 1×I2C. Up to 27 x 5 V-tolerant I/Os. 1.8–3.6 V, -40–85 °C. Compared to the LQFP-32 L031K6T6, this model uses an ultra-compact QFN package to further shrink PCB footprint while retaining the same I/O count and memory configuration, providing an ideal ultra-low-power solution for battery-powered, extremely space-constrained IoT nodes and portable devices.

STM32L031K6U6 Core Features

Core: Cortex-M0+ 32 MHz, low-power design

Memory: 32 KB Flash, 8 KB SRAM, 1 KB EEPROM

Analog: 12-bit ADC (10 ch)

Connectivity: 1×USART, 1×SPI, 1×I2C

Timers: LP Timer, GP Timers, RTC

I/Os: 27 (5 V-tolerant)

Package: UFQFPN-32

Temperature Range: -40°C to 85°C

STM32L031K6U6 Applications

IoT Sensor Nodes: Battery-powered environmental sensors, wireless modules

Portable Devices: Wearables, portable medical devices

Industrial Metering: Water, gas, and electricity meters

Consumer Electronics: Remote controls, e-labels, smart cards

Extremely Space-Constrained Low-Power Systems: Miniaturized controllers, energy harvesting nodes

STM32L031K6U6 Key Advantages

Ultra-Low Power: Multiple low-power modes extend battery life

1 KB EEPROM: Eliminates external storage for data logging

32-bit Performance, 8-bit Price: Enjoy the ARM ecosystem at a very low cost

27 I/Os + Ultra-Compact UFQFPN-32 Package: Perfect combination of rich pins and minimal size

5 V-tolerant I/Os: Enhanced robustness, simplified level shifting

Full Ecosystem Compatibility: Easy development with STM32CubeIDE/HAL/LL libraries

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FAQ

1. What is STM32L031K6U6 and what are its core features?
STM32L031K6U6 is an ultra-low-power 32-bit MCU from STMicroelectronics' STM32L0 series, built around an Arm® Cortex®‑M0+ core in a UFQFPN‑32 package (5 mm × 5 mm). Operating at 32 MHz, it provides 32 KB Flash and 8 KB SRAM, and integrates a 12‑bit ADC and a low‑power UART. This chip delivers core processing power in an extremely small package with very low power consumption, making it ideal for simple battery‑powered devices that demand long battery life and minimal cost without requiring a rich set of peripherals.

2. What are the key specifications of STM32L031K6U6?

• Core: Arm® Cortex®‑M0+, up to 32 MHz

• Memory: 32 KB Flash, 8 KB SRAM

• Operating Voltage: 1.65 V to 3.6 V

• Temperature Range: -40 °C to +85 °C (industrial grade)

• I/O Count: up to 25

• Package: UFQFPN‑32 (5 mm × 5 mm)

3. How does STM32L031K6U6 differ from STM32L051K6U6, and how do I choose based on project needs?
Both share the same 32‑pin QFN package, core, and memory configuration, but differ in peripherals. The L051 adds 2× SPI, 2× I²C, and capacitive touch sensing (TSC), while the L031 offers 1× SPI and 1× I²C, focusing on essential ultra‑low‑power processing and analog acquisition at a lower cost. If your application only needs to read a few sensors and communicate over a serial interface, the L031 is the more cost‑effective choice; if you need more digital interfaces or touch functionality, choose the L051.

4. Are 32 KB Flash and 8 KB SRAM sufficient? What real‑world applications can they support?
32 KB Flash can accommodate a compact bare‑metal program or a lightweight RTOS kernel, along with basic sensor drivers and a communication stack. 8 KB SRAM requires careful variable management, but is perfectly adequate for fixed‑function applications such as wireless sensor nodes, simple data loggers, and battery monitors. If more code space is needed, upgrade to a 64 KB Flash variant in the same package (e.g., STM32L051K8U6).

5. How does it perform in terms of low power consumption? What are the typical currents across its modes?

• Temperature Range: -40 °C to +85 °C

• Ultra‑low‑power modes:

  • Standby mode: ~0.27 µA (no RTC)

  • Stop mode: ~0.4 µA (no RTC), ~0.8 µA with RTC

  • Run mode: ~88 µA/MHz

6. How capable is the built‑in 12‑bit ADC? Can it meet typical sensor acquisition needs?
The ADC supports up to 16 external input channels, a maximum sampling rate of 1.14 Msps, 12‑bit resolution, and a built‑in window comparator. It is fully sufficient for common signals such as temperature, pressure, light, and battery voltage. It can also remain active in low‑power modes and wake the CPU via the analog watchdog, making it ideal for battery‑powered devices that periodically monitor analog signals.

7. What communication interfaces are integrated? Is there a low‑power UART?
The STM32L031K6U6 includes 1× SPI, 1× I²C, and 1× low‑power UART (LPUART). The LPUART can remain operational in Stop mode and wake the MCU upon address match or start bit detection, significantly reducing system standby power. This is particularly useful for applications that communicate with wireless modules or sensors over a serial link.

8. In the 32‑pin QFN package, are there enough GPIOs and analog inputs? Does it support capacitive touch?
The chip provides up to 25 I/Os, 16 of which can serve as ADC inputs—ample for a typical small sensor node. However, the STM32L031 series does not include capacitive touch sensing (TSC). If touch keys or sliders are required, consider upgrading to the STM32L051 series.

9. What development tools are needed for the STM32L031K6U6? Is there a suitable evaluation board?
ST provides free STM32CubeMX for graphical configuration and STM32CubeIDE as an integrated development environment, along with the STM32CubeL0 firmware library. Debugging and programming are handled by ST‑Link debuggers. For rapid prototyping, the NUCLEO‑L031K6 board features the same L031 chip in a 32‑pin package with identical pinout and functionality, allowing direct code migration to the target board.

10. If I later need more storage or richer peripherals, what upgrade options are available?
If more Flash or SRAM is needed, you can upgrade to a 64 KB variant in the same package (e.g., STM32L051K8U6) or to the LQFP‑48 STM32L051C8T6. If a segment LCD driver or USB is required, step up to the L052 or L053 series respectively. In all these upgrade paths, core code is reusable—only pin configuration and peripheral parameters need adjustment in STM32CubeMX.