| 摘要 |
<p>The present invention provides an LED driver circuit for extending a lifespan, which immediately senses malfunction of a corresponding switched mode power supply (SMPS) and operates another switched mode power supply to drive a load. The LED driver circuit for extending a lifespan, which drives a load including an LED string by driving a first switched mode power supply through applying power from a commercial power source, according to an exemplary embodiment of the present invention includes: a first relay connected to a power input terminal of the first switched mode power supply to switchover to an electrically off state when a normal output voltage of the first switched mode power supply is generated; a second switched mode power supply connected to an output terminal of the first relay; a second relay connected between the first switched mode power supply and the load to select an output circuit of any one of the first switched mode power supply and the second switched mode power supply; and an output voltage detection unit to detect the output voltage of the first switched mode power supply to switch the second relay to an on state to connect the first switched mode power supply to the LED string when a normal voltage is outputted, and to switch the first relay to an on state as well as to switch the second relay to an off state to supply an output voltage of the second switched mode power supply to the LED string when an abnormal voltage is outputted.</p> |
