| 摘要 |
PURPOSE:To simplify the configuration of a power source circuit by providing the first pulse width control circuit which controls the pulse width in response to the output voltage and the second pulse width control circuit which outputs a pulse having a width in response to the input voltage to the primary side of a transformer and controls the operation of the first control circuit. CONSTITUTION:The first pulse width control circuit PWM1 supplies a signal which has a pulse width in response to the output voltage to a drive circuit DRV, thereby driving a main transistor Q. On the other hand, the second pulse width control circuit PWM2 outputs a pulse which has a width in response to the input voltage to the primary side of a transformer T and a frequency lower than the output of the control circuit PWM1. The operation of the control circuit PWM1 is controlled by the output of the control circuit PWM2. |
