The ultra-low-power STM32L053x6/8 microcontrollers incorporate the connectivity power of the universal serial bus (USB 2.0 crystal-less) with the high-performance Arm® Cortex®-M0+ 32-bit RISC core operating at a 32 MHz frequency, a memory protection unit (MPU), high-speed embedded memories (up to 64 Kbytes of Flash program memory, 2 Kbytes of data EEPROM and 8 Kbytes of RAM) plus an extensive range of enhanced I/Os and peripherals. The STM32L053x6/8 devices provide high power efficiency for a wide range of performance. It is achieved with a large choice of internal and external clock sources, an internal voltage adaptation and several low-power modes. The STM32L053x6/8 devices offer several analog features, one 12-bit ADC with hardware oversampling, one DAC, two ultra-low-power comparators, several timers, one low-power timer (LPTIM), three general-purpose 16-bit timers and one basic timer, one RTC and one SysTick which can be used as timebases. They also feature two watchdogs, one watchdog with independent clock and window capability and one window watchdog based on bus clock. Moreover, the STM32L053x6/8 devices embed standard and advanced communication interfaces: up to two I2C, two SPIs, one I2S, two USARTs, a low-power UART (LPUART), and a crystal-less USB. The devices offer up to 24 capacitive sensing channels to simply add touch sensing functionality to any application. The STM32L053x6/8 also include a real-time clock and a set of backup registers that remain powered in Standby mode. Finally, their integrated LCD controller has a built-in LCD voltage generator that allows to drive up to 8 multiplexed LCDs with contrast independent of the supply voltage. The ultra-low-power STM32L053x6/8 devices operate from a 1.8 to 3.6 V power supply (down to 1.65 V at power down) with BOR and from a 1.65 to 3.6 V power supply without BOR option. They are available in the -40 to +125 °C temperature range. A comprehensive set of power-saving modes allows the design of low-power applications.