| 摘要 |
PROBLEM TO BE SOLVED: To solve the problems that in a conventional power unit an electronic load 8 is broken due to increase of an output voltage Vout when a negative feedback signal Vfb1 of the output voltage is disconnected and that no diagnosis can be made for the disconnection.SOLUTION: A pull-up current is prepared for a negative feedback terminal 10. When a disconnection occurs, the output voltage Vout is made to decrease to be 0 V by a negative feedback operation. Besides, a diagnosis whether the increase of the negative feedback signal Vfb1 is caused by a disconnection or an external voltage short cut can be made from results by an abnormality diagnosis comparator 6 at the time when the pull-up current 1 is switched ON or OFF.SELECTED DRAWING: Figure 1 |
