| 摘要 |
In a power supply device according to an embodiment, a reference signal Vref1, which changes from a value corresponding to a maximum current in a full lighting state to that corresponding to a minimum current in case of a deepest dimming depth, and a reference signal Vref2, which changes from a value corresponding to a load voltage at the time of a maximum current in a full lighting state to that corresponding to a minimum current in case of the deepest dimming depth, are prepared in accordance with dimming depths of a dimming signal. In a shallow dimming depth region close to a full lighting state, the reference signal Vref1 is selected to apply constant-current control to light-emitting diodes in a current control mode. In a deep dimming depth region, the reference signal Vref2 is selected to apply constant-voltage control to the diodes in a voltage control mode. |
