Abstract: A power-supply device includes a rectifying unit configured to rectify a phase-controlled AC voltage; a current limiting unit including a current limiting resistor, which limits an input current flowing from the rectifying unit at rise of a rectified voltage outputted from the rectifying unit; and an adjustment unit configured to cause the current limiting unit to limit the input current flowing from the rectifying unit until a predetermined time period has elapsed after an input of the AC voltage to the rectifying unit is started.

Abstract: A power-supply device includes a rectifying unit configured to rectify a phase-controlled AC voltage; a current limiting unit including a current limiting resistor, which limits an input current flowing from the rectifying unit at rise of a rectified voltage outputted from the rectifying unit; and an adjustment unit configured to cause the current limiting unit to limit the input current flowing from the rectifying unit until a predetermined time period has elapsed after an input of the AC voltage to the rectifying unit is started.

Abstract: Implemented are a switching power supply device and a light-emitting diode lighting device in which a variation in load current can be suppressed against a wide range of variation in AC voltage. The configuration of the switching power supply device and the light-emitting diode lighting device includes: a rectifier unit which rectifies AC input voltage and outputs pulsating-current voltage; a power converting unit which receives the pulsating-current voltage and supplies a predetermined load current to a load; a current detecting unit which detects the load current; a drive control unit which controls the power converting unit to regulate the load current to a constant level; and an input voltage detecting unit which detects a variation in the AC input voltage. The drive control unit controls the power converting unit depending on the variation in the AC input voltage detected by the input voltage detecting unit.

Abstract: A transformer includes: a core portion, which forms a magnetic circuit; a coil bobbin, which has a winding core portion to be wound by a winding wire, and which is attached on the core portion; a primary winding wire, which has a plurality of first divided winding wire portions divided in parallel; and a secondary winding wire, which has a plurality of second divided winding wire portions divided in parallel, wherein the plurality of first divided winding wire portions and the plurality of second divided winding wire portions are layered on the winding core portion, wherein at least one of the first divided winding wire portions becomes a first layer which is closest to the winding core portion, and at least one of the other of the first divided winding wire portions is interposed between two of the second divided winding wire portions.