What is the lowest power STM32 MCU? how to choose?

The lowest power STM32 microcontroller series is the STM32L series, especially the STM32L0 and STM32U5 families, which are specifically designed for ultra-low-power applications.

 STM32 MCU Families with Lowest Power Consumption

1. STM32L0 Series (Ultra-Low Power, Entry Level)

• Core: ARM Cortex-M0+

• Active current: ~87 µA/MHz

• Standby mode: ~250 nA (with RTC)

• Stop mode: ~300 nA

• Voltage: 1.65V to 3.6V

• Example part: STM32L072CZ

• Ideal for: Wearables, sensors, simple battery-powered devices

2. STM32L4 Series (Low Power + Higher Performance)

• Core: ARM Cortex-M4 (with FPU)

• Active current: ~100 µA/MHz

• Standby mode: ~100 nA

• Stop 2 mode: ~400 nA

• Example part: STM32L432KC

• Good balance between power and performance

3. STM32U5 Series (Most Advanced Low Power)

• Core: ARM Cortex-M33

• Active current: ~19 µA/MHz (extremely efficient)

• Stop mode: ~200 nA

• Standby with RTC: ~130 nA

• Security: TrustZone, AES, Tamper detection

• Example part: STM32U575ZIT6

• Best for: Secure, battery-powered IoT, medical, wearable

 Summary Table

 When to Choose What?

• Use STM32L0 if your project needs minimal resources and ultra-low power (e.g., simple sensor node).

• Use STM32L4 for moderate performance with low power (e.g., wearable device with UI).

• Use STM32U5 for complex, secure, low-power applications (e.g., medical device or secure IoT).

How to Choose the Lowest Power STM32 MCU?

 Step 1: Define Your Power Budget and Use Case

Ask:

• How often is the MCU active vs in sleep/standby?

• Will it run on battery? If so, how long?

• Does it need wireless, display, or security features?

 Step 2: Match Series to Your Needs

 Step 3: Check Specs Using ST’s Tools

Use:

• STM32CubeMX or STM32CubeIDE to explore pinouts, peripherals

• ST MCU Finder app (PC or mobile) to filter by power, Flash/RAM, packages, etc.

 Example: Choosing for a Battery Sensor Node

 Pro Tips

• Always check Stop/Standby current, not just active current.

• Use VBAT pin + RTC if you want low standby with timekeeping.

• Check for low-leakage GPIOs and independent I/O wakeup.

• Use LP modes + interrupts to stay in sleep as long as possible.