Automotive HID Headlamps: Producing Compact Electronic Ballasts using Power ICs

INCANDESCENT HALOGEN LAMPS have been the standard for automotive headlamps; however, metal halide high-intensity discharge (HID) lamps have slowly begun to be commercially used since the mid-1990s. The lighting system of the metal halide HID headlamp makes a great contribution to energy savings, longer lamp life and better visibility in traffic zones compared with halogen lamps. (Lamp life is lengthened because it prevents the loss of sodium metal as plus ions through the quartz of the lamp bulb.) This article describes power ICs consisting of full bridge inverters and their drivers in detail.