Patent ID: 8829810

Claim:
A circuit for controlling at least one LED with a characteristic forward voltage, wherein the LED is operable through at least one energy source, the circuit comprising first contacts for connecting the energy source, second contacts for connecting the at least one LED, and a step up converter, wherein the step up converter is connected with the first contacts and with the second contacts so that the step up converter provides a variable output voltage adapted to the characteristic forward voltage of the at least one LED at a substantially constant current independent from an input voltage provided by the energy source, wherein the circuit includes a device for detecting an undercut of a threshold value of the input voltage, and wherein the circuit includes a circuit unit for identifying an undercut of a threshold value of the input voltage, wherein the circuit unit is implemented as a feedback of an input and an output of the device for detecting an undercut of the threshold value of the input voltage through a capacitor, and wherein the circuit unit for identifying an undercut of the threshold value of the input voltage is connected with the second contacts so that it generates a blinking of the LED when the threshold value is undercut, wherein the blinking of the LED is implemented through the capacitor included in the circuit unit for identifying an undercut of a threshold value of the input voltage.