STMicroelectronics STM32L100 value line is an ultralow power MCU with a real time clock, 16-bit timers, comm interfaces such as SPI, I²C, USART, USB, 12-bit ADC, and a LCD driver interface. The ARM based Cortex processor entry level series operates from 1.8 to 3.6 volts and all STM32 L1 microcontrollers share the same architecture with pin to pin compatibility.

Flash memory: 64 Kb; SDRAM: 8Kb
STM32 L1: dynamic voltage scaling; ultralow power clock oscillator; LCD driver (up to 8x28 segments); comparator; DAC and hardware encryption
Temperature range: -40 to +85 °C

STM32L1 Series 32-Bit ARM® Cortex®-M3 Microcontrollers, STMicroelectronics

ARM® Cortex™-M3-based STM32 L1 series uses ST’s proprietary ultra-low-leakage process technology with an innovative autonomous dynamic voltage scaling and five (5) low-power modes offering unprecedented platform flexibility to fit any application. The STM32 L1 series extends the ultra-low power concept with no compromise on performance.

Ultra-Low-Power mode: 300nA with backup registers (3 wakeup pins)
Ultra-Low-Power mode + Real Time Clock (RTC): 900nA with backup registers (3 wakeup pins)
Low-Power Run mode: down to 9μA
Dynamic Run mode: down to 230μA/MHz