Circuit with a microcontroller for operating LEDs and for calculating the LED junction temperature

摘要

Circuit for operating and for determining the temperature of one or more LEDs (8) whose supply is interrupted periodically, characterized in that a small measuring capacitor (5) of the LED or multiple LEDs (8) is connected in parallel and a microcontroller (16), the forward voltage of the LED or of the plurality of LEDs at low current level, by picking up and evaluating the voltage (V LED) during the discharge measuring capacitor (5) after switching off (F) the LED or the plurality of LEDs (8) as follows: As soon as the fast Discharge of the measuring capacitor via the LED or LEDs is completed (B, G), the voltage value (E) of the transition to the slower slower discharge process (t G) is detected and this voltage value (E) assigned a temperature value.