These are the first STM32 MCUs based on near-threshold technology, delivering a breakthrough improvement in battery life. With near-threshold technology, the STM32U3 MCUs reduce the active consumption down to 9.5 μA/MHz, resulting in significant longer battery life for any application.
Powered by an Arm® Cortex®-M33 core running at 96 MHz, it delivers market-leading energy efficiency—up to 5 times better than previous generations, with 117 CoreMark/mW.
Flexible memory and packaging
With flexible memory options (256 Kbytes of RAM & up to 1 Mbytes of dual-bank flash) and a wide range of package choices, STM32U3 enables you to build compact, power-optimized devices tailored to your needs.
Enhanced security for mission-critical applications
Security is a core focus of the STM32U3, targeting PSA Certified Level 3 and SESIP Level 3 certifications to provide robust protection for sensitive and mission-critical systems.
Its dual-bank flash architecture supports seamless firmware updates without system downtime, an essential capability for safety-critical environments.
How STM32U3 makes a difference in your projects
- For applications requiring 3% of runtime time:
The STM32U3 is 2.2 times more energy efficient than the STM32U5 - In metering applications:
The STM32U3 delivers 1.4 times better energy efficiency compared to the STM32U5 - For applications with very low activity (0.04% runtime) and mostly in Stop mode:
The STM32U3 still achieves 1.2 times greater energy efficiency than the STM32U5
Even with very low duty cycles, the STM32U3 consistently outperforms the STM32U5 across different application profiles, whether consumer, metering, or industrial, making it a better choice for energy-sensitive projects.
For a detailed technical comparison of STM32U3 and STM32U5 peripheral compatibility, read the attached PDF.
STM32U3 block diagram
Additional resources
STM32U3:
- STM32U3 reference manual: RM0487
- STM32U3 Online Training
- Dedicated Wiki pages for Security with STM32U3
- Product overview - STM32U3
Product datasheets:
- DS14830 (STM32U385 – with crypto)
- DS14861 (STM32U375 – without crypto)
- STM32U3 errata sheet: ES0626
STM32U3 dedicated application notes:
- AN6011: Getting started with STM32U3 MCU hardware development
- AN6195: How to optimize power consumption on STM32U3 MCUs
- AN6012: Migrating between STM32U5 and STM32U3 MCUs
- AN6051: Migrating from STM32L4 and STM32L4+ to STM32U3 MCUs
Nucleo board: NUCLEO-U385RG-Q
ST Blog
- Sub-Threshold transistors: 3 answers to find your way in this CMOS region
- STM32U3: The 1st STM32 with a 0.65 V VCORE is making near-threshold CMOS mainstream
First published Jun 26, 2025
