The over-voltage auto power-down equipment setting circuit

Published:2011/6/19 0:49:00 Author:Seven | Keyword: over-voltage, power-down | From:SeekIC

The 220V mains provide with a stable 12V working voltage through C1, VD1 and DW1, and VD3, R2 and RP1 compose a voltage distributing sampling circuit. When the mains voltage is normal, DW2 is blocked, the working voltage on 5-pin of TWH8778 is lower than 1.6V, the relay J is open, the mains provides power normally after crossing the J-1 commonly closed touch spot; when the mains voltage is high than the normal value, DW2 is breakdown and conducting, LEV on 5-pin of TWH8778 is rising to 1.6v, which reverses IC, and the 3-pin outputs a high LEV, the relay is closed and the power supply of the electric apparatus is cut off immediately.



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