| 摘要 |
PURPOSE:To perform high efficiency by regulating a switching current flowed through a switching element and controlling the internal resistance of the element, thereby suppressing the self resonance of a stepup transformer. CONSTITUTION:A current detector 31 detects a switching current 33 flowed through a switching transistor 2 and the primary winding of a stepup transformer 4. At this time, the smaller a load resistor 6 and the larger a load are, the larger the switching current 33 becomes. A controller 32 controls the internal resistance of the transistor 2 in response to the output level of a current detector 31, and the larger the current 33 is, the smaller the resistance 2 of the transistor 2 becomes.
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