Dual-rail watchdog in a SOT-23-6
The MAX6831ZWUT+T from Maxim Integrated is a multi-voltage supervisor that monitors two independent supply rails with thresholds at 1.67 V and 2.313 V. It asserts a reset output (active low, open drain) whenever either monitored voltage drops below its threshold, and holds reset for a minimum of 140 ms after all rails return to tolerance.
What the 140 ms reset timeout buys you
A 140 ms minimum reset timeout is deliberately long enough to let the power supply and on-chip decoupling settle after a brownout or power-up event. In practice, this means the downstream processor, FPGA, or ASIC sees a clean, glitch-free release—no partial boot, no metastable register state. For designs that already have a separate watchdog timer, this supervisor serves as the voltage monitor only; the open-drain output can be wire-ORed with other reset sources on the same pull-up line.