| 摘要 |
PROBLEM TO BE SOLVED: To provide a highly efficient power circuit despite its use of a step-up- and-down chopper circuit. SOLUTION: An output voltage is distributed at resistor R1 and R2, inputted into an error amplifier 1 for a difference in voltage to be subtracted from that of a reference power source E1, inputted into a second PWM compactor 7 for pulse width modulation, and inputted into a second drive circuit 8. An output Vb of the error amplifier 1 is subtracted by a voltage V1 of an offset power source E2 by a subtraction circuit 4, inputted into a first PWM comparator 5 for pulse width modulation, and inputted into a first drive circuit 6. Only when a transistor Tr1 is turned on 100%, does a transistor Tr2 repeats turn on/off operations, so that a stage-up-and-down chopper circuit operates as a step-up circuit, and only when a transistor Tr2 is turned off 100%, the transistor Tr1 repeats the on/off operations, so that the step-up-and-down chipper circuit operates as a step-down circuit. |
