| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent elements from generating heat or being destroyed. <P>SOLUTION: A protection circuit for a switching power source comprises a Zener diode 16 which is connected between a transmission line A1 and a ground and yielded when the transmission line A1 is turned to a predetermined voltage higher than rating, a Zener diode D1 which is connected between the transmission line A1 and the ground and yielded when the transmission line A1 is turned to a predetermined voltage higher than the rating and lower than a Zener voltage of the Zener diode 16, a switch section which is inserted to a post-stage rather than a connecting spot of the Zener diodes 16 and D1 in the transmission line A1, outputs a power supply voltage to a load while a predetermined constant voltage is inputted to an output control terminal, and stops outputting the power supply voltage to the load while a ground voltage is inputted to the output control terminal, and a transistor Q1 which is turned on when the Zener diode D1 is yielded, and leads the output control terminal into the ground. <P>COPYRIGHT: (C)2013,JPO&INPIT |
