| 摘要 |
PURPOSE:To stabilize a converter output within a certain range by suppressing the converter output below a lower limit value by varying the duty cycle of the oscillation of a converter when the converter output exceeds the upper limit of the certain range, and stopping the oscillation of the converter when the output descends below the lower limit. CONSTITUTION:When the voltage of a lead storage battery P is, for example, 15 V and a converter output is above 17 V, a control transistor TRQ4 turns on, so the base potential of a TRQ3 drops according to the collector potential of the TRQ4 to control the duty ratio of the converter 3, so that the battery is charged while the converter output is suppressed below the upper limit value of a certain range. On the other hand, when the voltage of the battery P is a voltage decreasing the converter output below 13 V, for example, 10 V, the voltage of the variable terminal R'8 of a control circuit 42 is low and a difference between this voltage and the constant voltage of a constant voltage element Z1 decreases below the base-emitter threshold level of the TRQ3, so the TRQ3 is kept in the off state, so that the converter generates no output. |
