| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the problem that a potential of a switching (SW) terminal rises when a rectification diode comes off. <P>SOLUTION: A switching transistor M1 is arranged between the switching (SW) terminal and a ground terminal. An error amplifier 10 amplifies an error between a feedback voltage V<SB POS="POST">FB</SB>corresponding to an output voltage V<SB POS="POST">OUT</SB>and a prescribed reference voltage V<SB POS="POST">REF</SB>, and generates an error voltage V<SB POS="POST">ERR</SB>. A pulse modulator 12 generates a pulse signal S<SB POS="POST">P</SB>whose duty cycle is controlled in accordance with the error voltage V<SB POS="POST">ERR</SB>. A driver 14 drives the switching transistor M1 on the basis of the pulse signal S<SB POS="POST">P</SB>. An overvoltage detection circuit 20 generates an overvoltage protection (OVP) signal asserted when the voltage V<SB POS="POST">SW</SB>of the switching (SW) terminal becomes higher than a prescribed threshold voltage V<SB POS="POST">TH</SB>. A control circuit 100 performs a prescribed protection processing when the OVP signal is asserted. <P>COPYRIGHT: (C)2013,JPO&INPIT |
