Patent ID: 8853949

Claim:
An LED lighting device comprising: a DC/DC power converter having first and second converter output terminals and effective to supply an output voltage across the converter output terminals; first and second lighting device output terminals coupled to the first and second converter output terminals, respectively, and effective to receive an LED lamp; a current sensor coupled between one of the converter output terminals and a corresponding device output terminal, and effective to detect an output current; a voltage sensor coupled across the converter output terminals and effective to detect the output voltage; and a control circuit which controls the DC/DC power converter to adjust the output voltage based on the output current detected by the current sensor with respect to a target value, compares the output voltage detected by the voltage sensor to a predetermined upper limit value, and upon the output voltage exceeding the predetermined upper limit value, disables the DC/DC power converter, measures an accumulated lighting time of the device, and after the accumulated lighting time has exceeded a predetermined switching time, decreases the upper limit value as the accumulated lighting time passes, and identifies when the accumulated lighting time has exceeded a predetermined reset disabling time subsequent to the predetermined switching time, wherein the control circuit does not reset the accumulated lighting time even upon the reset condition being met.