Patent ID: 9137855
Filing Date: 2015-09-15
Classification: G01R,G03G,H05B

Abstract:
1. An AC voltage detection circuit that detects a voltage input from an AC power supply comprising: a pair of input terminals to which a voltage is applied from the AC power supply; a limiting circuit that allows a current when a positive voltage applied to the input terminals exceeds a predetermined first threshold value, and allows a current when an absolute value of a negative voltage applied to the input terminals exceeds a predetermined second threshold value different from the first threshold value; a first detection circuit that detects that the positive voltage is applied to the input terminals and thus the limiting circuit allows the current; and a second detection circuit that detects that the negative voltage is applied to the input terminals and thus the limiting circuit allows the circuit wherein the limiting circuit is a circuit including a first limiting circuit that is connected across the pair of input terminals to allow a current when the positive voltage applied to the first limiting circuit exceeds a predetermined first voltage and a second limiting circuit that is connected in series with the first limiting circuit between the pair of input terminals to allow a current when an absolute value of the negative voltage applied to the second limiting circuit exceeds a predetermine second voltage different from the first voltage.