US 12,424,820 B2
Laser diode driving circuit
Yusuke Nakakohara, Kyoto (JP); and Tan Nhat Hoang, Kyoto (JP)
Assigned to Rohm Co., Ltd., Kyoto (JP)
Appl. No. 17/767,245
Filed by Rohm Co., Ltd., Kyoto (JP)
PCT Filed Aug. 26, 2020, PCT No. PCT/JP2020/032145
§ 371(c)(1), (2) Date Apr. 7, 2022,
PCT Pub. No. WO2021/079611, PCT Pub. Date Apr. 29, 2021.
Claims priority of application No. 2019-192903 (JP), filed on Oct. 23, 2019.
Prior Publication US 2022/0376470 A1, Nov. 24, 2022
Int. Cl. H01S 5/042 (2006.01); G01S 7/484 (2006.01); H01S 5/0233 (2021.01)
CPC H01S 5/0428 (2013.01) [G01S 7/484 (2013.01); H01S 5/0233 (2021.01)] 17 Claims
OG exemplary drawing
 
1. A laser diode driving circuit comprising:
a switching element;
a controller configured to turn on and off the switching element;
a second series circuit connected in parallel with a first series circuit including a laser diode; and
a capacitor, and
a shunt resistor configured to detect a current passing through the laser diode, wherein
the second series circuit includes a rectifying element and a current limiter configured to limit a current passing through the rectifying element, the second series circuit being connected in parallel with the first series circuit such that a direction pointing from an anode to a cathode of the rectifying element is opposite to a direction pointing from an anode to a cathode of the laser diode, and
the capacitor is configured
to be charged when the switching element is off and
to form a closed circuit with the switching element and the first and second series circuits when the switching element is on,
the shunt resistor is included in the first series circuit, and
an impedance of the shunt resistor is configured to be lower than an impedance of the current limiter.