What the 2.93V threshold and active-low reset mean for your rail
The STM809SWX6F: That 140 ms minimum timeout gives downstream logic—MCUs, FPGAs, or SoCs—time to complete an orderly power-down or hold in reset until the supply is stable. The push-pull, totem-pole output drives the reset line high or low without needing an external pull-up resistor. Active-low reset is the standard polarity for most ARM Cortex-M and other microcontroller families—a direct connection to the /RST pin, no inversion stage needed. The threshold accuracy over temperature is tight enough to guard against brownout conditions in 3.3 V and 3.0 V systems without false resets from normal ripple.
Package and board-fit for the SOT-23-3 footprint
Housed in the industry-standard SOT-23-3 (TO-236, SC-59) package, the STM809SWX6F occupies minimal PCB area—roughly 2.9 mm × 1.3 mm—and is compatible with the same footprint used by competitors' reset ICs. The three pins are supply, ground, and reset output; no external components are required beyond the decoupling cap at the VDD pin.