LED driving circuitry with variable load to control output light intensity of an LED

摘要

Circuitry for driving an LED array and a lamp including such circuitry. A fixed current source outputs a fixed current to an LED array. A variable load is provided in parallel to the LED array to also receive an output from the fixed current power supply. The variable load senses a condition affecting a luminous output of the LED array and varies an impedance based on this sensed condition. This variable load may typically include a thermistor or a photodetector. As the impedance of the variable load changes, current diverted from the LED to the variable load changes. Thereby, current supplied to the LED array, and thereby the intensity LED, can be controlled based on the impedance changing element in the variable load.