Patent ID: 8860427

Claim:
An apparatus for detecting failures in an illumination device comprising a plurality of light emitting diodes connected in series, the device comprising: a first circuit node, a second circuit node, and a third circuit node for interfacing the illumination device such that a voltage supplying the plurality of light emitting diodes is applied between the first and the second circuit node and a first fraction of a supply voltage drop is provided between the third and the second circuit node; and an evaluation unit coupled to the first circuit node, the second circuit node, and the third circuit node and configured to assess whether a voltage present at the third circuit node is within a pre-defined range of tolerance about a nominal value that is defined as a second fraction of the supply voltage present between the first and the second circuit node, voltage adjustment circuitry configured to preset the second fraction such that the nominal value substantially equals the voltage present at the third circuit node when the illumination device includes only faultless light emitting diodes.