| 摘要 |
PROBLEM TO BE SOLVED: To provide a light emitting element driving circuit making it possible to adjust a resistance value while suppressing a rise in cost. SOLUTION: A drive current control circuit 15 has a temperature-nondependent constant-current circuit 20 which outputs a first current I1, a temperature-dependent constant-current circuit 21 which outputs a second current I2 dependent on temperature, and a current mirror circuit 22 which generates a drive current Ia driving a semiconductor laser 11 according to a third current obtained by adding the first current I1 and second current I2 together, and a first resistance unit 31 and a second resistance unit 35 of the constant-current circuits have first to third resistance elements R20-1 to R20-3, and R21-1 to R21-3 each having one end connected in common, and semiconductor switches SW which are provided corresponding to the first to third resistance elements R20-1 to R20-3, and R21-1 to R21-3, and connect/disconnect the other-end sides of the resistance elements to a ground potential based on voltage potential level of control lines L1 to L3. COPYRIGHT: (C)2009,JPO&INPIT
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