Analog Bits Power-On Reset (POR) macro comprehensively addresses typical SOC start-up power supply monitoring needs, in a fully integrated easy-to-use macro. The POR includes an internal bandgap style voltage reference circuit which is used as a reference to compare the power supplies against. The POR further includes its own timebase reference circuit, so requires no clock or other synchronizing signal to work correctly. Only when both IO and Core power supplies have both exceeded a user-selected voltage level for a user-selected time, will the outputs signal that power is good.