Client: NXP Semiconductors
NXP Semiconductors develops and produces, among other things, chips for controlling LEDs. One of the application areas is in the replacement market of the 12 Volt low voltage halogen lamps (MR16). The problem in this market is that in many installations use is made of a conventional (incandescent) dimmer, together with an electronic transformer which is intended for halogen lamps, making dimming an issue.
NXP has developed a chip for this market that makes it possible to dim LED lights via the existing dimmer and transformer. The chip controls a boost and a buck converter, which makes this arrangement possible. For this chip we have designed and implemented the controller of the buck-driver. Through measurements in combination with smart algorithms all manner of things are regulated, such as the output current, flutter compensation, and various protections. In addition, an algorithm automatically detects the optimal control mode (CCM or DCM), and switches from one mode to another without any visible effects.