| 摘要 |
PURPOSE:To suppress rapid reduction in an output voltage even if an input voltage is interrupted at any state by cutting off an output control transistor (TR) when the input voltage drops rapidly. CONSTITUTION:When the input voltage VIN drops to be VIN<=VOUT-VT (where VT is the voltage of a level shift circuit giving a prescribed potential difference between the input terminal and the inverting input of a comparator A2), the output of the comparator A2 goes to a high level. Thus, the current of a diode Q2 is interrupted and a transistor (TR)Q3 is cut off. Further, an error amplifier A1 interrupts an output current when a control voltage VCNT, i.e., an output of the comparator A2 reaches a high level. Thus, the base current of the TRQ1 is cut off and then the Q1 is cut off. Thus, the electric charge stored in an output capacitor C2 is not discharged to the input circuit and the rapid reduction in an output voltage VOUT is prevented. |
