48 MHz Cortex-M0+ in a 3x3 mm QFN
The NXP MKL03Z16VFG4 is a 32-bit ARM Cortex-M0+ MCU from the Kinetis KL03 series, clocked at 48 MHz. It packs 16 KB Flash and 2 KB RAM in a 16-QFN (3x3 mm) exposed-pad package — sized for space-constrained sensor nodes or simple control modules. The 7-channel 12-bit ADC handles analog inputs directly, keeping the BOM count low.
16 KB Flash — firmware budget is tight
16 KB Flash is the hard limit for compiled code. That fits a bootloader, a Modbus RTU slave stack, or a sensor-fusion algorithm.