STM32L412KBT6 ST Mainstream Arm Cortex-M4 Ultra-Low-Power 32-bit MCU 128KB Flash 40KB SRAM USB ADC Comparator LQFP-32

STM32L412KBT6 Product Overview

STM32L412KBT6 is an Arm Cortex-M4 MCU at 80 MHz with FPU, LQFP-32. 128 KB Flash, 40 KB SRAM, USB 2.0 FS device (crystal-less), 12-bit ADC (8 ch), two comparators, LP timers, RTC, 2×USART, 1×UART, 1×LPUART, 2×SPI/I2S, 3×I2C. Up to 26 x 5 V-tolerant I/Os. 1.71–3.6 V, -40–85 °C. As a value-line member of the STM32L4 series, the STM32L412KBT6 packs Cortex-M4 performance and crystal-less USB into a compact 32-pin package, purpose-built for power-, cost-, and space-sensitive battery-powered IoT nodes, portable devices, and sensor applications.

STM32L412KBT6 Core Features

Core: The STM32L412KBT6 features an Arm Cortex-M4 core at 80 MHz, with FPU + ART Accelerator

Memory: The STM32L412KBT6 provides 128 KB Flash and 40 KB SRAM (incl. 8 KB with HW parity), offering a balanced combination for embedded applications

USB: The STM32L412KBT6 integrates a USB 2.0 FS device (crystal-less)

Analog: 12-bit ADC (8 ch), 2×Comparators

Connectivity: 2×USART, 1×UART, 1×LPUART, 2×SPI/I2S, 3×I2C

Timers: 1×Advanced Timer, multiple GP/LP timers, RTC

I/Os: 26 (5 V-tolerant)

Package: LQFP-32

Temperature Range: -40°C to 85°C

STM32L412KBT6 Applications

IoT Sensor Nodes: Battery-powered wireless sensors and USB data acquisition modules can leverage the STM32L412KBT6's low power and compact size

Portable Devices: Wearables, portable medical devices, and USB peripherals benefit from the STM32L412KBT6's integration

Industrial Metering: Water, gas, and electricity meters are ideal applications for the STM32L412KBT6

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

Space-Constrained Low-Power Applications: Miniaturized controllers and energy harvesting nodes can rely on the STM32L412KBT6

STM32L412KBT6 Key Advantages

Cortex-M4 + FPU + Ultra-Low Power: The STM32L412KBT6 delivers excellent DSP and floating-point performance while maintaining extremely low power consumption

Integrated Crystal-less USB: The STM32L412KBT6 enables USB communication without an external crystal, simplifying design and saving BOM

128 KB Flash + 40 KB SRAM: The STM32L412KBT6 provides ample storage for complex programs and data processing

2 Built-in Comparators: Signal threshold detection without external components

26 I/Os in Compact LQFP-32 Package: The STM32L412KBT6 offers a perfect balance of rich pins and minimal size, saving PCB space

5 V-tolerant I/Os: Enhanced system noise immunity and simplified external level-shifting circuitry

Full Ecosystem Compatibility: Easy development with STM32CubeIDE/HAL/LL libraries for the STM32L412KBT6

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FAQ

1. What is STM32L412KBT6?
STM32L412KBT6 is an ultra-low-power 32-bit MCU from STMicroelectronics' STM32L4 series, based on an Arm® Cortex®-M4 core with FPU and DSP instructions in an LQFP-32 package (7 mm × 7 mm). Operating at 80 MHz, the STM32L412KBT6 provides 128 KB Flash and 40 KB SRAM, a USB 2.0 full-speed device interface, a 12-bit 5 Msps ADC, and ultra-low-power comparators. Delivering USB connectivity and high energy efficiency in an extremely compact 32-pin footprint, the STM32L412KBT6 is a cost-effective single-chip solution for space- and power-constrained battery-powered devices.

2. What are the key specifications of STM32L412KBT6?

• Core: Arm® Cortex®-M4, up to 80 MHz, 100 DMIPS with FPU and DSP

• Memory: 128 KB Flash, 40 KB SRAM

• Operating Voltage: 1.71 V to 3.6 V

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

• I/O Count: up to 26

• Package: LQFP-32 (7 mm × 7 mm)

3. What are the advantages of the LQFP-32 package on the STM32L412KBT6, and is it easy to hand-solder?
The LQFP-32 has all pins exposed with a generous 0.8 mm pitch, making it even easier to hand-solder the STM32L412KBT6 than finer 0.5 mm pitch packages. Drag-soldering with a standard soldering iron is straightforward—no hot-air station required. At just 7 mm × 7 mm, the STM32L412KBT6 strikes an excellent balance between manual assembly convenience and miniaturization for wearables, sensor nodes, and tiny USB dongles.

4. What applications is STM32L412KBT6 suitable for?
Thanks to its ultra-compact 32-pin package, 128 KB Flash, USB device interface, and rich low-power modes, the STM32L412KBT6 is ideal for space- and power-constrained portable devices such as miniature USB dongles, wearable medical patches, wireless sensor nodes, ultra-compact IoT endpoints, and embedded controllers needing simple USB connectivity.

5. What development tools support STM32L412KBT6?
ST provides free STM32CubeMX for graphical configuration and STM32CubeIDE as an integrated development environment for the STM32L412KBT6, along with the STM32CubeL4 firmware library. Debugging and programming use ST-Link debuggers. The NUCLEO-L412RB board (LQFP-64) offers a convenient prototyping platform—though it has more pins, the peripherals and software are fully compatible with the STM32L412KBT6, enabling seamless migration to the smaller 32-pin package after validation.

6. What is the power consumption of the STM32L412KBT6 across its low-power modes?

• Temperature Range: -40 °C to +85 °C

• Ultra-low-power modes of the STM32L412KBT6:

  • Shutdown mode: ~33 nA (5 wake-up pins)

  • Standby mode: ~125 nA (5 wake-up pins), ~430 nA with RTC

  • Stop 2 mode: ~1.2 µA, ~1.4 µA with RTC

  • Run mode: ~100 µA/MHz (LDO mode)

7. Which pins does USB occupy on the STM32L412KBT6 in the 32-pin package, and does it limit GPIO availability?
USB Device on the STM32L412KBT6 requires D+ (PA12) and D- (PA11) as the differential data pair, and typically also uses VBUS detect (PA9) and ID (PA10), consuming a total of four I/Os. With 26 I/Os available on the STM32L412KBT6, approximately 22 GPIOs remain for other peripherals after USB is configured—ample for most small-scale designs. Use STM32CubeMX for pin planning to allocate USART, SPI, I2C, and ADC functions efficiently.

8. How does STM32L412KBT6 differ from STM32L412RBT6?
Both share the same core, memory (128 KB Flash, 40 KB SRAM), and peripherals (USB Device, ADC, comparators). The only differences are the package and I/O count: the STM32L412KBT6 uses an LQFP-32 with 26 I/Os, while RBT6 uses an LQFP-64 with 52 I/Os. If your design stays within 26 I/Os and requires the smallest possible footprint and lowest cost, the STM32L412KBT6 is the more compact and economical choice.

9. Is 40 KB SRAM on the STM32L412KBT6 enough to run a USB stack, and what optimization techniques are recommended?
The 40 KB SRAM on the STM32L412KBT6 can comfortably run a lightweight RTOS (e.g., FreeRTOS) and USB device libraries (CDC, HID) with proper memory management. Use static allocation to reduce fragmentation, disable unused library modules, and leverage DMA for data transfers to lower RAM usage on the STM32L412KBT6. If larger buffers are needed, external SPI Flash or FRAM can be added via the SPI interface.

10. What if my project needs CAN or a DAC? Can STM32L412KBT6 support that?
The STM32L412KBT6 does not include a native CAN controller or DAC. If CAN is essential, consider the STM32L432 or STM32L433. If you must stay with the STM32L412KBT6, you can add an external SPI-to-CAN controller (e.g., MCP2515) and an external DAC chip (e.g., MCP4725) via I2C/SPI, but this will increase circuit complexity and BOM cost—evaluate early during component selection.