In one general aspect, an apparatus can include a first voltage detect circuit configured to produce an output signal at a first power supply voltage, and configured to be in a non-monitoring state at a second power supply voltage greater than the first power supply voltage. The apparatus can include a second voltage detect circuit configured to change from a non-monitoring state to a monitoring state and configured to produce an output signal at a third power supply voltage between the first power supply voltage and the second power supply voltage. The apparatus can also include a combination circuit configured to produce a power-on-reset signal based on a logical combination of the output signal produced by the first voltage detect circuit and the output signal produced by the second voltage detect circuit.