1.9V threshold supervisor in a SOT-23-3
The Microchip MCP121T-195I/TT is a simple reset/power-on reset supervisor that monitors a single voltage rail and asserts a reset signal when the supply drops below 1.9V. The output is active-low open-drain, so it can be wire-ORed with other reset sources or pulled up to any voltage up to the absolute maximum of the open-drain transistor.
Active-low open-drain output — wired-OR compatible
Because the output is open-drain and active-low, this part can share a common reset line with other supervisors, a manual reset button, or a watchdog timer without contention. The pull-up resistor value sets the rise time; for a SOT-23-3 layout with short traces, a 10 kΩ pull-up to the MCU supply is typical. The 1.9V threshold is a good fit for monitoring a 1.8V or 2.5V core rail — it asserts before the logic becomes indeterminate.
Industrial temperature range and active lifecycle
The SOT-23-3 package is a standard footprint — easy to hand-solder or reflow, and the small body keeps board area to a minimum.