| US 7,492,799 B2 | ||
| Light-emitting element driver | ||
| Mitsuyori Saitoh, Itabashi-ku (Japan); and Hiroshi Watanabe, Tokyo (Japan) | ||
| Assigned to Texas Instruments Incorporated, Dallas, Tex. (US) | ||
| Filed on Nov. 01, 2006, as Appl. No. 11/555,502. | ||
| Prior Publication US 2007/0098027 A1, May 03, 2007 | ||
| Int. Cl. H01S 5/062 (2006.01) | ||
| U.S. Cl. 372—38.02 [372/38.01; 372/38.07; 372/29.011] | 19 Claims |
| 1. A laser diode driver comprising:
a photodiode for converting the optical output of a laser diode into current;
a first monitor voltage generator that generates a first monitor voltage with a magnitude equal to the product of the current
flowing through said photodiode and a first coefficient;
a first closed-loop circuit that supplies a bias current to the laser diode such that said monitor voltage becomes equal to
a first reference voltage corresponding to the first optical output reference value selected for setting the bias current
of said laser diodes;
a second monitor voltage generator that generates a second monitor voltage with a magnitude equal to the product of the current
flowing through the photodiode and a second coefficient;
a second closed-loop circuit that supplies a switching current to the laser diode such that the second monitor voltage becomes
equal to a second reference voltage corresponding to the second optical output reference value selected for setting the switching
current of said light-emitting element; and
a switch circuit for connecting the photodiode to the first monitor voltage generator in a first mode and to the second monitor
voltage generator in a second mode.
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