Driver circuit for a solid state optical emitter device

摘要

The present invention relates to a circuit for driving a solid state optical emitter device such as a laser diode, and in particular a circuit which limits the maximum current which may be drawn through the device. The circuit comprises a current supply path and a current return path to which the optical emitter may be connected, and current limit means (20) to limit a maximum current (Imax) that may flow through one of the current paths. The current limit means (20) has a current mirror with an input portion (21) and an output portion (23), the circuit being arranged so that when a first current (IR) flows through the input portion (21) the second portion (23) is predisposed to supply a second current (Io) up to a maximum which mirrors the first current (IR). The maximum current (Imax) through the paths is thereby limited in accordance with the maximum of the second current (Io).