Patent attributes
A power supply circuit includes a first voltage regulator, a second voltage regulator, and a voltage comparator. The first voltage regulator is connected to a direct current power supply, and regulates a direct current supply voltage down to a first voltage level to output a first voltage at a first output terminal. The second voltage regulator is connected to the first voltage regulator, and regulates the first output voltage down to a constant, second voltage level to output a second voltage at a second output terminal. The voltage comparator is connected to the first and second voltage regulators, compares the first output voltage against a given threshold level greater than the second voltage level, and deactivates the second voltage regulator until the first output voltage exceeds the given threshold level upon startup of the power supply circuit.
