| 摘要 |
PROBLEM TO BE SOLVED: To provide a power device at a low cost an ion simple constitution, by which stand-by power can be lowered without requiring an expensive internal power supply as an auxiliary power supply circuit, when power supply from a main power supply circuit to a control circuit is interrupted for reducing stand-by power. SOLUTION: A stand-by mode decision circuit 4 transmits the command of the interruption of the power supply of a main power-supply circuit 1 to a main power-supply interrupting circuit 3, under a state in which there is no input signal from the outside for a fixed time period and a control circuit may transfer to a stand-by mode, and the control circuit transfers to the stand-by mode. The control circuit 2 is supplied with a power supply required for maintaining the stand-by mode from an auxiliary power-supply circuit 5 at that time. Stand-by power can be lowered, because a dissipation current and potential supplied to the control circuit 2 are set in a minimum required for the stand-by mode by setting the constants of the R1 and R2 of the auxiliary power-supply circuit 5, and the power device at a low cost can be obtained, because the auxiliary power supply circuit can be constituted only of a resistor. |
