A power supply voltage detector circuit monitors a ramping supply voltage and selectively enables a voltage divider for operation to divide the ramping supply voltage in response to the ramping supply voltage exceeding a first threshold. Additionally, a variable resistance of the voltage divider is changed in response to the ramping supply voltage exceeding a second threshold. A voltage output from the voltage divider is used to generate a bandgap voltage used as a reference voltage in comparison operations for controlling enabling of the voltage divider and selection of the variable resistance.