Lighting circuit and vehicle lamp

Abstract

A lighting circuit configured to light a light source, the lighting circuit comprising: a first terminal configured to receive a first power supply voltage; a second terminal configured to receive a second power supply voltage; a power supply output circuit configured to output a first voltage corresponding to the first power supply voltage, regardless of whether the second power supply voltage is applied to the second terminal, when the first power supply voltage is applied to the first terminal, and output a second voltage corresponding to the second power supply voltage, when the second power supply voltage is applied to the second terminal without the first power supply voltage being applied to the first terminal; and a driver circuit configured to supply a first current to the light source, based on the first voltage, when the first voltage is outputted from the power supply output circuit, and supply a second current to the light source, based on the second voltage, when the second voltage is outputted from the power supply output circuit, wherein an input current used to detect a disconnection in the light source flows through the first terminal, when the first power supply voltage is applied to the first terminal.

Dependencies are inferred from the claim text.