| 摘要 |
PURPOSE:To obtain a power supply apparatus of flexible performance and high safety factor, by a method wherein it is judged whether an input power source is for alternate current or for direct current, and a discriminant control circuit for controlling the action of a switching power supply circuit is provided. CONSTITUTION:After AC power from input terminals 1A, 1B is rectification- smoothed by a rectification circuit 2 or the like, the power is fed to the primary winding of an insulating transformer 5 via a switching transistor (hereinafter called 'Tr')4 through a switching power supply circuit. The Tr4 is driven by a switching control circuit 6 of PWM system, and via the secondary winding, output rectification diode 8, and the like, DC power for output is provided through the output ends 13A, 13B. Then, to the switching power supply circuit, a discriminant control circuit 30 for discriminating whether the input power is of alternate current or of direct current and for controlling the action of said power supply circuit most adequately based upon the result of the judgement is added thereto. Only at the time of AC input, current flows into capacitors C1, C2, and starting voltage of a starting circuit 14 is automatically switched. |
