32 MHz Cortex-M0+ with 1.65 V floor — the ultra-low-power baseline
It runs at 32 MHz and packs 128 KB of Flash, 20 KB of SRAM, and 6 KB of embedded EEPROM — the EEPROM eliminates the external serial memory chip for parameter storage. The supply range down to 1.65 V means it can run directly from a single alkaline cell or a Li-ion battery near end-of-discharge, which is the main reason you pick this over a 2.0 V-minimum Cortex-M0+ part.
Memory sizing — 128 KB Flash / 20 KB SRAM / 6 KB EEPROM
128 KB of Flash is enough for a modest application stack — a BLE beacon firmware, a sensor hub, or a simple motor controller — but you will bump into the ceiling if you try to run a full RTOS with a TCP/IP stack and a GUI. The 20 KB SRAM is tight for large buffers; plan your DMA and USB packet buffers carefully. The 6 KB EEPROM is a genuine hardware EEPROM, not emulated Flash, so you get 100k-cycle endurance per byte without wear-leveling code.
The 1.65 V minimum supply voltage is the headline feature of the STM32L0 family. Most competing Cortex-M0+ MCUs need at least 2.0 V or 2.4 V, which forces a boost converter or a second cell. Here you can run the MCU directly from a single AA alkaline (1.65 V at end-of-life) or a Li-ion cell (3.6 V max). The internal oscillator and all peripherals remain functional across the full range, so no brownout surprises when the battery sags.
There is no AEC-Q100 qualification on this part, so it is not rated for under-hood automotive or engine-bay environments. For cabin or infotainment applications where the ambient stays below 85°C, it is fine — but verify the customer's thermal spec before committing.
Package and I/O — 32-UFQFPN with 25 GPIO
Housed in a 32-UFQFPN (5x5 mm) with an exposed pad, this package is a compact surface-mount footprint suited for space-constrained PCBs. The 25 I/O lines include peripherals such as I²C, SPI, UART/USART, USB, and IrDA.
STMicroelectronics lists the STM32L072KBU6TR as Active. This part is still in volume production and suitable for new designs. The base product number STM32L072 covers a range of density and package variants, so if you later need more Flash or a different pin count, you can move within the family without a full redesign.