US Patent 11871492 Light emitting element drive device and light emitting system

A light emitting element drive device includes a driving circuit that supplies a variable drive current to a light emitting unit having one or more light emitting elements so that the light emitting unit can emit light, a drive reference voltage generation circuit that generates a drive reference voltage defining the upper limit value of the drive current and supplies the same to the driving circuit, and a specific external terminal capable of connecting to an external resistor. The drive reference voltage generation circuit operates selectively in a first mode to generate the drive reference voltage regardless of the state of the specific external terminal, or a second mode to generate the drive reference voltage in accordance with a second mode current through the specific external terminal.