Patent ID: 8358085

Claim:
A method for determining a temperature of at least one light emitting diode (LED) in a circuit which includes a power supply for powering the LED, where the LED is operable to generate light, the method comprising: providing an operating current and an operating voltage to the LED; superimposing a first current pulse on the operating current; sensing a magnitude of a first voltage pulse across the LED resulting from the applied first current pulse superimposed on the operating current; superimposing at least a second current pulse, different from the first current pulse, on the operating current; sensing a magnitude of a second voltage pulse across the LED resulting from the applied second current pulse superimposed on the operating current; deriving an operating temperature curve utilizing (i) logarithms of magnitudes of the first and second current pulses and (ii) magnitudes of the first and second voltage pulses; determining a slope of the operating temperature curve; and determining an operating temperature of the LED based on the determined slope of the operating temperature curve.