| 摘要 |
<P>PROBLEM TO BE SOLVED: To obviate re-adjustment of a duty ratio for obtaining a desired output value accompanying providing a dead time. <P>SOLUTION: A switch timing control circuit comprises a PWM circuit 24 which outputs a ramp wave (j) and a pulse wave (c) which are synchronized with each other; a comparator 28 which outputs a signal Vg1 performing duty control on an MOSFET 16, based on the result of the comparison between the ramp wave (j) and the pulse wave (c) from the PWM circuit 24; a level shift circuit 30, 32 for changing a level of the ramp wave (j) from the PWM circuit 24; comparators 34, 36, 40, 42 which output signals (e), (f), (g), (h) performing duty-control on an MOSFET 18, which operates inversely to the MOSFET 16, based on a result of comparison between a level-shifted ramp wave (a), (b) and the pulse wave (c) from the PWM circuit 24 or a waveform (d) inverting that pulse wave (c); and an adjustment circuit 26 for controlling the amount of level shift due to the level shift circuits 30, 32 so as to set the switch timing of the MOSFET 18. <P>COPYRIGHT: (C)2007,JPO&INPIT |
