International Rectifier (El Segundo, CA) introduced the 600V IR2159 Dimming Ballast Controller IC, which is claimed to feature a new control method of regulating lamp power that eliminates requirements for a current-sensing transformer. The new ICs offer the high- and low-side gate drives for half-bridge MOSFETs, as well as a comprehensive set of protection features, guarding against end of lamp life, capacitive mode, brown-out and overtemperature. The IR2159 IC is built around a novel phase control loop that senses and regulates the phase current of the half-bridge. Only a single pin with an external current-sensing resistor is used to measure all feedback information necessary for pre-heat, ignition, dimming and lamp fault. The resulting closed loop system is claimed to offer the simplest architecture for linear dimming ever developed, without requiring a separate current-sensing transformer or precision trimming of the external timing components. The IR2159 600V Dimming Ballast Controller IC is available in a 16-pin DIP or SOIC package. Prices start at $5.95 in quantities of 1,000. A Reference Design Kit (IRPLDIM1) of dimming ballast designed to drive a T8 tube is provided.