32 MHz Cortex-M0+ with embedded EEPROM — the field-swap angle
The STM32L073CBU6 is an STMicroelectronics ultra-low-power 32-bit MCU built around the ARM Cortex-M0+ core running at 32 MHz. The 48-UFQFN package with exposed pad (7x7 mm) is small enough for compact PCBs but needs a thermal via stitch under the pad if you push continuous current through the I/O banks. Orientation is marked by a chamfer on pin 1 — visible under magnification, but I would still hit it with a continuity check before reflow if the board is going into a sealed enclosure.
Peripheral set and connectivity — what is on the bus
This MCU includes a USB interface, which the B* questions flag as a common search point — yes, it supports USB. On the analog side there are ten 12-bit ADC channels and two 12-bit DAC outputs. The peripheral list includes a brown-out detect, POR, PWM timers, a watchdog, DMA, I²S, and an LCD driver — the LCD segment is unusual for this class and saves an external display controller in metering or control-panel designs. With 37 I/O lines in a 48-pin package, you get decent GPIO density for a small-footprint board.
That means no last-time-buy deadline looming, no pressure to qualify a replacement for a production line. The base product number is STM32L073, so future variants in the same family share the same peripheral map and pinout — good for a roadmap hedge.
Sourcing — quoted to order, no shelf-stock illusion
The active lifecycle means the supply channel is stable, but the 48-UFQFN package is not a commodity jellybean, so lead time varies with batch. Get a quote before you commit the BOM line.