3.075V threshold — the reset trigger level
The MCP120T-315I/SN is a simple reset/power-on reset IC from Microchip that monitors a single voltage rail and asserts an active-low reset signal when the supply drops below 3.075V. This threshold is set for 3.3V logic systems where the supervisor must trip before the downstream devices enter an undefined state. The reset output is open-drain, so it can be wire-ORed with other reset sources on the same bus.
150ms reset timeout — sizing for power-up settling
For a typical MCU with a 10ms power-up delay, this margin is comfortable; for a larger system with multiple rails and a PLL, the 150ms window may need to be verified against the slowest rail's rise time.