The STM32 F0 clock system is optimized for power efficiency. The A/D converter with auto-off mode guarantees an optimum conversion speed thanks to its independent clock source. Communications peripherals with independent baud rates from the CPU frequency have wake-up from stop low-power mode capability. The STM32 F0 consumes as little as 0.43 µA in V bat with the real-time clock running, enabling low-power devices to keep track of clock time. The calendar RTC with sub-ppm digital calibration resolution can be enabled in all low-power modes. The 31 µs minimum RTC step is well fitted to RF applications. This allows the MCU to wake-up after a precise, given time from low-power mode and allows any RF application to detect the presence of any RF communication.