| 摘要 |
PURPOSE: To provide a drive circuit for a high withstand voltage type switching element in which the effect provided by EMI noise is avoided even when a through-current is generated. CONSTITUTION: The drive circuit for the high withstand voltage type switching element is provided with a main MOS transistor TR 1 for high withstand voltage type switching, a load 2, a gate control MOS TR 3, and a boosting circuit 20. An oscillator deciding a pumping frequency of the boosting circuit 20 is a frequency variable type oscillator 21, being a ring oscillator where multi-stages of inverters IN1-IN5 are connected as a loop and has a switch SW switching a 3-stage ring oscillator or a 5-stage ring oscillator. The oscillated frequency is varied by the switching of the switch SW and the generated frequency by a through-current (i) produced by totempole configuration sets 12a, 14a (comprising TRs Q13 , Q14 and TRs Q23 , Q24 respectively) is varied. Thus, a frequency at which electromagnetic noise is generated can be set to a frequency area where no adverse effect is given and a fault onto a surrounding electric device can be avoided. |
