OVERCURRENT PROTECTION CIRCUIT, AND CONTROL METHOD OF THE SAME

PROBLEM TO BE SOLVED: To obtain an overcurrent protection circuit capable of surely performing operation without increasing power source capacity for melting a fuse, even when reproducibility of melting is low due to influence of a peripheral temperature or the like of a fuse and short circuit is caused by low-resistance short circuit.SOLUTION: An overcurrent protection circuit: uses a first fuse and a second fuse in which a melting threshold is lower than a maximum current value in normal operation of a load circuit; is configured so that a first current line including the first fuse and a second current line including a switch connected to the second fuse in series are connected to each other in parallel; includes a current value detection part for detecting a current value flowing in the load circuit; and is configured so as to open/close the switch included in the second current line on the basis of the current value of the load circuit detected by the current detection part. 【課題】 ヒューズの周囲温度等の影響による溶断の再現性が悪く、低抵抗短絡による短絡であっても、ヒューズ溶断のための電源容量を増やすことなく確実に動作可能な過電流保護回路を得る。【解決手段】 溶断閾値が負荷回路の正常動作における最大電流値よりも低い第一および第二のヒューズを用い、第一のヒューズを含む第一の電流線路と第二のヒューズに直列接続される開閉器を含む第二の電流線路とを並列接続し、負荷回路に流れる電流値を検出する電流値検出部を備え、この電流検出部によって検出される負荷回路の電流値に基づいて第二の電流線路に含まれる開閉器を開閉するように構成した。【選択図】 図１