SIGNAL TRANSMISSION CIRCUIT, POWER UNIT AND LIGHTING DEVICE

PROBLEM TO BE SOLVED: To provide a signal transmission circuit, a power unit and a lighting device that implement desired signal resolution while suppressing power consumption.SOLUTION: A signal transmission circuit 30 comprises: a photo coupler 21; a current amplification section 40; a current-voltage conversion section 50 and the like. The current amplification section 40 includes transistors 221, 231, resistances 222, 232 and the like, and amplifies a current flowing through a phototransistor 212. The current-voltage conversion section 50 includes a resistance 24, and converts the current amplified by the current amplification section 40 to a voltage. The current-voltage conversion section 50 transmits (outputs) the conversion voltage to a microcomputer 14 on an output side of the phototransistor 212.