TWO-MODE SWITCHING POWER SUPPLY

摘要

A switched-mode power supply having at least two output terminals for supplying at least two different voltages and capable of operating in an alternate state in which some of the voltages are reduced. The power supply includes at least two controllable voltage sources coupled, respectively, to the output terminals and at least one voltage regulating circuit coupled to control inputs of the voltage sources for reducing the output voltages of both voltage sources proportionately when the voltage on the output of a first one of the voltage sources exceeds a preset reference level. The power supply further includes a circuit for selectively coupling a second one of the voltages sources to the regulating circuit. If the output of the second voltage source exceeds that of the first voltage source, when the second voltage source is coupled to the regulating circuit, the output voltages of all the voltage sources are reduced proportionately, while the voltages on the power supply output terminals are also reduced except for the output terminal coupled to the regulating circuit.