Processor PMIC with 32µA standby overhead
The 1.8V to 5.5V supply range lets this part sit on a single-cell Li-ion (3.0V-4.2V nominal) or a regulated 5V rail without a pre-regulator — the BOM saves the LDO or buck that a fixed-input PMIC would need.
81-DSBGA 3.6x3.6mm — footprint and fan-out
The 81-DSBGA (3.6x3.6mm) package is a 0.4mm-pitch BGA — the 3.6mm body keeps the board footprint small, but the fine pitch demands a 4-layer PCB minimum for fan-out; two-layer boards will struggle to route all balls without via-in-pad.