A lighting circuit drives a light source including plural light emitting elements and includes a bypass switch circuit which includes plural bypass switches connected in parallel with the plural light emitting elements, a boost converter which boosts a power supply voltage to generate a direct current voltage stabilized at a variable target voltage, a buck converter which receives the direct current voltage to supply a driving current stabilized at a target current to the light source and which includes a hysteresis controller configured to stabilize the driving current between a peak value and a bottom value and to change a difference between the peak value and the bottom value such a switching frequency of the buck converter approaches a constant value, and a voltage adjusting circuit which is configured to dynamically change the target voltage of the boost converter according to an output voltage of the buck converter.
LIGHTING CIRCUIT AND VEHICLE LAMP
2018-03-01
Patent
Electronic Resource
English
IPC: | B60Q ARRANGEMENT OF SIGNALLING OR LIGHTING DEVICES, THE MOUNTING OR SUPPORTING THEREOF OR CIRCUITS THEREFOR, FOR VEHICLES IN GENERAL , Anordnung von Signal- oder Beleuchtungsvorrichtungen, deren Einbau oder Halterung oder deren Schaltkreise bei Fahrzeugen allgemein / H05B ELECTRIC HEATING , Elektrische Heizung |
European Patent Office | 2016
|European Patent Office | 2016
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