Abstract: A lighting circuit applied to a vehicle lighting tool includes: a power supply line to which power supply voltage is supplied in a first period of time out of a predetermined cycle including the first period of time and a second period of time, the supply of the power supply voltage being stopped in the second period of time; a regulator that supplies driving current to a light source based on the power supply voltage across the power supply line; a detection circuit that detects whether there is an abnormality in the light source; a signal output circuit that operates based on the power supply voltage across the power supply line and outputs a signal according to a detection result of the detection circuit; and a control circuit that stops an operation of the regulator when the signal indicating that there is an abnormality in the light source is output.

Abstract: A linear regulator supplies a first drive current to a first light source in a first period in which the first light source is turned on and a second light source is not turned on, and in a second period in which the first light source and the second light source are turned on, and stops the supply of the first drive current in a third period in which the first light source and the second light source are turned off. A switching regulator supplies a second drive current to the second light source in the second period, and stops the supply of the second drive current in the third period.

Abstract: A linear regulator (40) supplies a first drive current (I1) to a first light source (24) in a first period in which the first light source (24) is turned on and a second light source (25) is not turned on, and in a second period in which the first light source (24) and the second light source (25) are turned on, and stops the supply of the first drive current (I1) in a third period in which the first light source (24) and the second light source (25) are turned off. A switching regulator (41) supplies a second drive current (I2) to the second light source (25) in the second period, and stops the supply of the second drive current (I2) in the third period.

Abstract: A lighting circuit which lights a semiconductor light source, the lighting circuit includes a drive circuit configured to receive a PWM signal from a controller, to generate a drive current to the semiconductor light source, and to switch the drive current according to the PWM signal. When a non-input state of the PWM signal exceeds a predetermined time, the lighting circuit is configured to assert an abnormality detection signal and to output the abnormality detection signal to the controller.

Abstract: A lighting circuit which lights a semiconductor light source, the lighting circuit includes a drive circuit configured to receive a PWM signal from a controller, to generate a drive current to the semiconductor light source, and to switch the drive current according to the PWM signal. When a non-input state of the PWM signal exceeds a predetermined time, the lighting circuit is configured to assert an abnormality detection signal and to output the abnormality detection signal to the controller.