A lighting device includes an electrical circuit for energizing an LED light source. The electrical circuit is configured to: have a target relationship between two illuminating operational parameters of the LED, connect the LED to a power source, energize the LED with a voltage waveform to effect a current waveform, determine a magnitude of each of the two operational parameters, determine an operational relationship between the two operational parameters, compare the target relationship with the operational relationship, determine a difference between the target relationship and the operational relationship and respond to the difference by adjusting the voltage waveform such that it changes one or both operational parameters to bring the operational relationship towards the target relationship.