| 摘要 |
A power supply system comprises: a switching power supply for generating a DC voltage by rectifying and smoothing an AC voltage of an AC power supply; a control device switching the switching power supply between the normal mode and a power saving mode; and a low-capacity power supply circuit supplying electric power to the control device in the power saving mode. The low-capacity power supply circuit includes: two capacitors, each including one end connected to the AC power supply; a rectifier circuit that is electrically connected between the other ends of the capacitors, and rectifies the AC voltage applied between the first and second capacitors; and a zero-crossing detecting circuit that is connected to a current path at the rear stage of the rectifier circuit, and detects zero-crossing points of the AC power supply. |
