Patent ID: 6978008

Claim:
A zero crossing detection circuit, comprising: an input terminal; an output terminal; a first node, a second node and a third node, being connected to the input terminal; a composite element, connected across the first node and the second and third nodes, the composite element comprising a first switch element connected across the first node and the second node, a second switch element connected across the first switch element and the third node, and a third switch element connected across the second switch element and the first node, the first switch element entering an on state when a polarity of a signal input to the input terminal reverses, and entering a short circuit state when the third switch element enters an on state, the second switch element entering an off state when polarity of the signal input to the input terminal reverses and entering an on state when the signal input to the input terminal reaches a specified potential; a fixed current circuit connected across the second node and the output terminal, and operating when the second switch element is in the on state; and a limit circuit limiting current flowing in the fixed current circuit and connected across the third node and the output terminal.