To cause a ripple current at load drive time to be reduced and enable stable current supply such as when sequentially turning a plurality of light-emitting elements on.SOLUTION: The constant current circuit comprises: an output circuit 103 having a first switch M31 for turning a first drive voltage VOUT1 on and off, a second switch M32 for turning a second drive voltage VOUT2 on and off, and an inductor L3; and a control circuit 100 for controlling the on/off of the switches M31, M32 in accordance with a detection voltage VR3 that is proportionate to a drive current ILED as the output current flowing in a lighting circuit 6 of the load. The second drive voltage is smaller than the first drive voltage. The control circuit 100 exercises control by turning the first switch M31 on when an error signal proportionate to a difference between the detection voltage VR3 and a reference voltage VREF3 that indicates the desired amount of output current is smaller than a triangular wave VTRI as a reference signal, and turning the second switch M32 on when the difference signal is larger than the reference signal.SELECTED DRAWING: Figure 1
【課題】複数の発光素子を順次点灯させる場合などの負荷駆動時のリプル電流を低減させ、安定した電流供給を可能にする。【解決手段】第1の駆動電圧VOUT1をオンオフする第1のスイッチM31、第2の駆動電圧VOUT2をオンオフする第2のスイッチM32、及びインダクタL3を有する出力回路103と、負荷の点灯回路6に流れる出力電流としての駆動電流ILEDに比例する検出電圧VR3に応じて、スイッチM31,M32のオンオフを制御する制御回路100とを備える。第2の駆動電圧は、第1の駆動電圧より小さい電圧である。制御回路100は、検出電圧VR3と出力電流の目標量を指示する参照電圧VREF3との差に比例する誤差信号が、参照信号としての三角波VTRIより小さい場合に第1のスイッチM31をオンし、誤差信号が参照信号より大きい場合に第2のスイッチM32をオンする制御を行う。【選択図】図1
CONSTANT CURRENT CIRCUIT
定電流回路
2022-02-03
Patent
Electronic Resource
Japanese
IPC: | H02M APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS , Anlagen zur Umformung von Wechselstrom in Wechselstrom, von Wechselstrom in Gleichstrom oder umgekehrt, oder von Gleichstrom in Gleichstrom und zur Verwendung in Netzen oder ähnlichen Stromversorgungssystemen / 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 |
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