Patent ID: 8115396

Claim:
An LED lamp protecting circuit comprising: an LED lamp comprising at least one LED; a constant current source comprising positive and negative input terminals for receiving electric power from an outer power source, positive and negative output terminals for supplying electric current to the LED lamp connected therebetween, and a switch for controlling electric connection or disconnection between the outer power source and the LED lamp; and a buffer circuit connected between the negative output terminal and the LED lamp, the buffer circuit comprising a charging capacitor, a first transistor and a second transistor, wherein the first transistor is NPN transistor, the second transistor is PNP transistor, an emitting electrode of the second transistor is connected to the LED lamp, a collecting electrode of the second transistor is electrically connected to the negative output terminal, the charging capacitor has a first end electrically connected to the emitting electrode of the second transistor and a second end connected to a ground, a base electrode of the first transistor is electrically connected to the first end of the charging capacitor, a collecting electrode of the first transistor is electrically connected to a base electrode of the second transistor, and an emitting electrode of the first transistor is connected to the ground.