| 摘要 |
<p>A switching power supply device which is disposed in an electronic equipment, generates a direct current voltage which has a first voltage value that is set in advance from electric power which is supplied from a commercial power source, and supplies a direct current voltage based on the generated direct current voltage to a device that is disposed in the electronic equipment, the switching power supply device includes; a direct current voltage generating portion which has a switching element and a transformer and generates a direct current voltage having at least one voltage value from the power that is supplied from the commercial power source through the switching element and the transformer; a control voltage detecting portion which detects a control voltage that is a voltage which is proportional to voltage of a secondary side of the transformer; a feedback current detecting portion which detects a feedback current that is current which is approximately proportional to a direct current voltage that is generated by the direct current voltage generating portion and corresponds to the first voltage value; at least one over current generating portion which becomes conduction state and makes over current that is current of a prescribed current threshold value set in advance or more flow to the secondary side of the transformer in case where voltage value of the direct current voltage which is generated by the direct current voltage generating portion is a prescribed voltage threshold value set in advance or more; a control portion which has an over current protection circuit that makes the direct current voltage generating portion stop generation of the direct current voltage in case where an over current which is current of the current threshold value set in advance or more flows in the secondary side of the transformer, and controls the direct current voltage which is generated by the direct current voltage generating portion based on the voltage value of the control voltage and electric current value of the feedback current; a constant voltage output portion which direct current voltage that corresponds to the first voltage value generated by the direct current voltage generating portion is input to, and outputs direct current voltage that has a second voltage value which is different from the first voltage value; and a feedback current decreasing portion which makes electric current value of the feedback current that is detected by the feedback current detecting portion to be electric current value of feedback current when the direct current voltage generated by the direct current voltage generating portion has a voltage value which is less than the first voltage value in case where voltage value of a load side of the constant voltage output portion is a prescribed voltage threshold value set in advance or less.</p> |
