Active-silicon sourcing — STM32L422TBY6TR lifecycle and BOM fit
ROHS3 compliance is confirmed on the manufacturer record, so the part passes the restricted-substance thresholds for EU and most global markets without a waiver.
Cortex-M4 core and memory — what 80 MHz and 128 KB flash buy you
128 KB of on-chip flash and 40K x 8 (40 KB) of SRAM leave room for a moderate application stack: the flash holds a FreeRTOS kernel plus application code, while the SRAM buffers a few hundred samples from a 10-channel 12-bit ADC before DMA transfer to memory.
WLCSP package — board-level reality check
The 36-WLCSP (Wafer-Level Chip-Scale Package) measures 2.58 mm x 3.07 mm, which is a true chip-scale footprint — no plastic overmold, just the silicon die with solder balls directly on the pads. This package demands a controlled reflow profile and a clean assembly process: the solder balls are the only standoff, so board flex or uneven solder paste thickness can crack joints.