Item specifics
Description
STM32G431KBU3 Product Overview
STM32G431KBU3 is a Cortex-M4 MCU at 170 MHz with FPU and math accelerator, UFQFPN-32. 128 KB Flash, 32 KB SRAM, USB 2.0 FS device (crystal-less), CAN FD, two 12-bit ADCs (5 Msps, 11 ch), two 12-bit DACs, two op-amps (PGA), two comparators, advanced motor control PWM, LP timers, RTC, 2×USART/UART, 1×SPI/I2S, 1×I2C. 26 x 5 V-tolerant I/Os. 1.7–3.6 V, -40–125 °C. Compared to the LQFP-32 G431KBT6, uses a smaller QFN package and extends temperature to 125°C, ideal for high-temperature, space-constrained digital power and motor control.
STM32G431KBU3 Core Features
Core: Cortex-M4 170 MHz, FPU + ART Accelerator + Math Accelerator (FMAC, CORDIC)
Memory: 128 KB Flash, 32 KB SRAM
Analog: 2×12-bit ADCs (5 Msps, 11 ch), 2×12-bit DACs, 2×PGAs, 2×Comparators
Motor Control: 2×Advanced Timers (PWM/Deadtime/Brake), multiple GP/LP timers
Connectivity: USB 2.0 FS (Crystal-less), CAN FD, 2×USART/UART, 1×SPI/I2S, 1×I2C
I/Os: 26 (5 V-tolerant)
Package: UFQFPN-32
Temperature: -40°C to 125°C
STM32G431KBU3 Applications
Digital Power: SMPS, Inverters, PFC
Motor Control: FOC, BLDC/PMSM Drives, Servo Controllers
Instrumentation: High-Precision Sensor Conditioning & Data Acquisition
Consumer Electronics: Drones, Power Tools, Portable Medical
Automotive/Industrial: CAN FD Nodes, Industrial Automation (high-temp)
STM32G431KBU3 Key Advantages
128 KB Flash + 170 MHz Cortex-M4 + FPU + Math Accelerator: Large memory and blazing-fast DSP
2 Op-Amps + 2 DACs + 2 Comparators + ADC: Complete analog chain in a tiny QFN package, saves BOM
USB 2.0 + CAN FD: High-speed USB and industrial CAN bus on one chip
-40–125°C Wide Temperature: Suitable for harsh industrial and automotive environments
26 I/Os in Ultra-Compact 32-Pin QFN: High-density connectivity for space-constrained high-temp control
1.7–3.6 V Wide Supply: Flexible for battery and various power sources
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FAQ
1. What is the STM32G431KBU3, and how small is its package?
The STM32G431KBU3 is an ultra‑compact high‑performance mixed‑signal MCU from STMicroelectronics' STM32G4 series, built around an Arm® Cortex®‑M4 core (170 MHz with FPU and DSP) in a UFQFPN‑32 package measuring just 5 mm × 5 mm. Despite its tiny footprint, it integrates 128 KB dual‑bank Flash, 32 KB SRAM, two rail‑to‑rail op‑amps, two ultra‑low‑power comparators, a 12‑bit 5 Msps ADC, a 12‑bit DAC, and FDCAN and USB‑C interfaces. The “U3” suffix indicates an extended temperature range (-40 °C to +125 °C), making it ideal for battery‑powered or high‑temperature devices where PCB space and thickness are extremely constrained—such as micro motor drives, sensor nodes, and wearable industrial equipment.
2. Is the UFQFPN‑32 (5 mm × 5 mm) package difficult to solder? Is it suitable for hand assembly?
This package is extremely small, with all pins hidden underneath; reflow soldering or a hot‑air station is required, and hand soldering with an iron is not feasible. It is primarily intended for automated SMT production to maximize PCB space savings. For prototyping, it is strongly recommended to first develop and debug on a NUCLEO‑G431KB board (LQFP‑32) before migrating to the UFQFPN‑32 chip. If hand‑solderability is preferred, choose the LQFP‑32 STM32G431KBT3.
3. Can the op‑amps and comparators still be used in such a small package? Won't there be a pin shortage?
They can be used without issue. Although the pin count is limited to 32, the op‑amps and comparators can be internally routed to the ADC or timers without consuming external pins, or using only a very small number. For single‑ or dual‑current‑sensing motor‑control or digital‑power applications, the two op‑amps and two comparators are sufficient to build a complete control loop, eliminating external analog ICs and delivering great value on a tiny PCB.
4. Does this chip support CAN FD and USB‑C? Can they be used simultaneously in the 32‑pin package?
Yes. It integrates an FDCAN controller (Flexible Data‑Rate CAN, up to 5 Mbps) and a USB‑C power‑delivery and communication controller (up to 15 W, USB 2.0 full‑speed). Although the 32‑pin package limits the number of simultaneously available peripherals, flexible pin‑multiplexing still allows CAN FD and USB‑C to be used together, with a few UART or SPI channels remaining for sensor connections. It is recommended to plan the pin‑out using STM32CubeMX in advance.
5. What practical benefits does the extended temperature range (-40 °C to +125 °C) provide?
The “U3” suffix designates an extended temperature grade. All datasheet performance parameters—including 170 MHz operation, 5 Msps ADC accuracy, and op‑amp specifications—are guaranteed across the full -40 °C to +125 °C range. For micro‑controllers installed in engine compartments, sun‑exposed outdoor cabinets, or high‑temperature industrial sites, this wide‑temperature capability directly translates into long‑term system reliability, without concerns about thermal throttling or unexpected resets.
6. Is 128 KB of Flash sufficient, and does it support safe OTA updates?
128 KB of Flash can accommodate optimized motor FOC algorithms, digital power firmware, and a CANopen stack. It supports a dual‑bank architecture (each bank 64 KB), allowing OTA updates by executing from one bank while programming the other, with automatic rollback on verification failure. This enables secure remote firmware updates even for devices deployed in harsh, hard‑to‑reach environments.
7. How much does power consumption increase at 125 °C, and how should thermal design be handled?
Static leakage current rises somewhat at high temperatures, but the STM32G4's 90 nm low‑power process effectively suppresses leakage. Full‑load power consumption remains manageable. For the UFQFPN‑32 package, heat is conducted primarily through the bottom pad and ground planes. A solid ground copper pour beneath the chip, a multi‑layer PCB, and multiple thermal vias are recommended. No external heatsink is typically needed for reliable operation at 125 °C.
8. What development tools are needed, and is it compatible with the existing STM32 ecosystem?
It is fully compatible with the STM32Cube ecosystem, including the free STM32CubeMX and STM32CubeIDE, and the STM32CubeG4 firmware package. If you already have projects based on STM32F3, G4, or other series, the HAL code can be reused directly; the main adjustments involve pin configuration and enabling analog peripherals. Official example projects for motor control and digital power are also provided to accelerate development.
9. Compared to the STM32G431KBT3 (LQFP‑32), what advantages does the KBU3 offer?
Both share the same core, memory, and all peripherals. The difference is the package: the KBU3 uses a UFQFPN‑32 (5 mm × 5 mm, bottom pads) that occupies even less PCB area and has a lower profile, ideal for extremely space‑constrained designs. The KBT3 uses an LQFP‑32 (7 mm × 7 mm, exposed pins) that is easy to hand‑solder and visually inspect, making it suitable for prototyping and low‑volume production. Choose based on your assembly capabilities and space constraints.
10. If I later need more I/Os, HRTIM, or larger memory, what upgrade options are available?
If you need more I/Os or the HRTIM, you can upgrade to LQFP‑48 or LQFP‑64 variants in the same series (e.g., STM32G431RBT3 or STM32G474RET3). For larger Flash or SRAM, choose a higher‑end configuration in the G474 series. All these upgrades remain within the STM32Cube ecosystem, allowing extensive code and hardware design reuse with minimal migration effort.