What the 20-pin TSSOP package means for your layout
The small footprint targets space-constrained PCBs where a larger LQFP package won't fit — think sensor nodes, dongles, or single-function control modules. With only 15 I/O, you have to plan peripheral muxing early. The USB interface (full-speed device) shares pins with UART and SPI, so you can't run all three simultaneously.
48 MHz Cortex-M0 — enough for control-loop and USB tasks
The ARM Cortex-M0 core runs at 48 MHz. The 12-bit ADC has 11 channels. DMA offloads peripheral transfers.