The access line ultra-low-power STM32L051x6/8 microcontrollers incorporate 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 (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 STM32L051x6/8 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 STM32L051x6/8 devices offer several analog features, one 12-bit ADC with hardware oversampling, 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 STM32L051x6/8 devices embed standard and advanced communication interfaces: up to two I2C, two SPIs, one I2S, two USARTs, a low-power UART (LPUART), .
The STM32L051x6/8 also include a real-time clock and a set of backup registers that remain powered in Standby mode.
The ultra-low-power STM32L051x6/8 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.

All features
Ultra-low-power platform
1.65 V to 3.6 V power supply
-40 to 125 °C temperature range
0.27 μA Standby mode (2 wakeup pins)
0.4 μA Stop mode (16 wakeup lines)
0.8 μA Stop mode + RTC + 8-Kbyte RAM retention
88 μA/MHz in Run mode
3.5 μs wakeup time (from RAM)
5 μs wakeup time (from Flash memory)

Core: Arm? 32-bit Cortex?-M0+ with MPU
From 32 kHz up to 32 MHz max.
0.95 DMIPS/MHz

Memories
Up to 64-Kbyte Flash memory with ECC
8-Kbyte RAM
2 Kbytes of data EEPROM with ECC
20-byte backup register
Sector protection against R/W operation

Up to 51 fast I/Os (45 I/Os 5V tolerant)
Reset and supply management
Ultra-safe, low-power BOR (brownout reset) with 5 selectable thresholds
Ultra-low-power POR/PDR
Programmable voltage detector (PVD)

Clock sources
1 to 25 MHz crystal oscillator
32 kHz oscillator for RTC with calibration
High speed internal 16 MHz factory-trimmed RC (+/- 1%)
Internal low-power 37 kHz RC
Internal multispeed low-power 65 kHz to 4.2 MHz RC
PLL for CPU clock

Pre-programmed bootloader
USART, SPI supported
Development support
Serial wire debug supported

Rich Analog peripherals
12-bit ADC 1.14 Msps up to 16 channels (down to 1.65 V)
2x ultra-low-power comparators (window mode and wake up capability, down to 1.65 V)

7-channel DMA controller, supporting ADC, SPI, I2C, USART, Timers
7x peripheral communication interfaces
2x USART (ISO 7816, IrDA), 1x UART (low power)
Up to 4x SPI 16 Mbits/s
2x I2C (SMBus/PMBus)

9x timers: 1x 16-bit with up to 4 channels, 2x 16-bit with up to 2 channels, 1x 16-bit ultra-low-power timer, 1x SysTick, 1x RTC, 1x 16-bit basic, and 2x watchdogs (independent/window)
CRC calculation unit, 96-bit unique ID
All packages are ECOPACK2