The STM32L0 series are ultra-low-power microcontrollers combined with an ARM Cortex-M0+ 32-bit RISC core. They are best fit for applications operating on battery or supplied by energy harvesting. New autonomous peripherals reduce the load with fewer CPU wake-up interrupts.
The STM32L0 series offers dynamic voltage scaling, an ultra-low-power Clock Oscillator, LCD interface, Comparator, DAC and hardware encryption.

STM32L0 Series 32-Bit ARM® Cortex®-M0+ Microcontrollers, STMicroelectronics

The STM32 L0 Series of the 32-bit Flash Microcontrollers (MCUs) is based on the ARM Cortex™-M0+ core; a core specifically developed for embedded applications. STMicroelectronics’s STM32 ARM Cortex™ M processor benefits from the Cortex-M0+ architectural enhancements including digital signal processing, real-time performance, low voltage and ultra low power. ST’s ARM® STM32 L0 ultra-low power series delivers a 32-bit performance and is ideal for small projects or platform decisions with its easy to use functionality.