Power supply circuit and luminaire

摘要

According to an embodiment, there is provided a power supply circuit (14) including a power converting unit (20), a current adjusting unit (23), and a control unit (21) and a luminaire (10) including the power supply circuit (14). The power converting unit (20) converts an alternating-current voltage into a direct-current voltage and supplies the direct-current voltage to the load (12). The alternating-current voltage is subjected to conduction angle control and is supplied via a power supply path (25). The current adjusting unit (23) includes a branch path (24) electrically connected to the power supply path (25) and can switch a first path state and a second path state. The first path state feeds a part of an electric current flowing through the power supply path (25) to the branch path (24). An electric current flowing to the branch path (24) in the second path state is smaller than the electric current in the first path state. The control unit (21) detects a conduction angle of the alternating-current voltage, controls the conversion of the direct-current voltage by the power converting unit (20) according to the detected conduction angle, and controls the current adjusting unit (23) according to the detected conduction angle.