New AC step driver for LED bulbs improves line regulation two-fold

Exar has expanded its industry-leading offering of AC step driver solutions for LED bulbs with the introduction of the XR46073. The XR46073 is a two-step LED current controller for AC step driving with improved line regulation primarily for A19 LED bulb applications. The line regulation of the XR46073 is improved by a factor of two over Exar’s prior generation. Patented AC step driving ICs provide industry-leading solutions for bulb, tube and downlight applications that do not require the use of inductors, transformers, electrolytic capacitors or metal oxide varistors (MOVs), depending on the specific requirements of the application. This enables users to eliminate their separate driver circuit board and greatly reduce the total BOM cost for their LED bulbs. In addition, these solutions deliver a very high power factor, very low THD, high surge immunity, low flicker and dimming capability with a wide range of industry-standard TRIAC dimmers. Exar’s prior generation of AC step drivers is comprised of single-step controllers, each controlling an individual current level to the LEDs. The XR46073 integrates two steps of current control to the LED strings, greatly improving the line regulation of the circuit by monitoring the line voltage and adjusting LED drive current proportionally. “The XR46073 is a terrific addition to our world leading AC step driving solutions for the bulb market,” said Steve Bakos, Exar’s vice president, lighting and display products. “Its high level of integration and improved line regulation allow our customers to hit extremely aggressive price points while delivering the performance required for the majority of the worldwide markets.” Also included in the XR46073 is over-voltage protection and over-temperature protection. Unlike some competing solutions, during an over temperature condition, the XR46073 smoothly and continuously reduces current to the LED string, reducing power dissipation in the process, until temperatures have stabilized at an acceptable level. The XR46073 is available in a RoHS compliant, green/halogen free, space-saving 2mm x 2mm DFN package.