Nanopower supervisor for 1.5V rails
The TPS3899DL15DSER is a fixed-threshold voltage monitor from TI's nanopower supervisor family, designed to assert a reset when the monitored rail drops below 1.5V. It draws negligible quiescent current — typical for the series — which makes it a fit for battery-powered or always-on systems where every microamp counts. The output is open-drain, active-low, so it can be wire-ORed with other reset sources or pulled up to a different voltage than the monitored rail. The 619ms typical reset timeout gives the supply time to stabilise after power-up before the processor starts executing.
Fixed threshold, wide temperature range
This part monitors a single voltage with a factory-set threshold of 1.5V — no external resistor divider needed. That makes it a drop-in choice for 1.5V core or I/O rails, but it won't work for a 3.3V or 5V rail without an external divider (which defeats the simplicity).