Dimmability, i.e. the capability of being dimmed, is an important feature of future lighting applications. Dimmability is one of the enablers of a range of smart functionalities. One of the most common dimming techniques is the so called phase cut dimming, which is used in SSL (Solid State Lighting) devices, such as lamps. In order to make the SSL application compatible with phase cut dimmers, appropriate measures must be taken in the design of the driver, which drives the very light generator of the SSL device. As shown in FIG. 1, those measures typically involve the placement of fusistors 106 in cascade to the connection pins 102 connecting the SSL device 100 to the power supply, typically the mains. Phase cut dimming introduces high current peaks. In order to limit these currents, damping resistors 106 at the input of SSL device 100 are applied. Because of safety these resistors 106 are fusible, and such a fusible resistor is called a fusistor 106. The fusistors 106 are typically placed on the same circuit board 104 as the remaining driver components 108, which are in turn connected with the very light emitting unit 110, including for instance light emitting diodes 112 arranged on a further circuit board 114.
The fusistors 106 are responsible for a considerable amount of heat generation during the operation of the SSL device, in the range of 20% of the total thermal power dissipated in the driver. Moreover, stringent thermal requirements on current SSL applications require that any effort be taken to effectively manage all thermal loads, spreading them as much as possible, and removing them from thermal paths which are heavily loaded and/or poorly conducting. Doing so in an inexpensive way is also important.