Dimmable LED controllers drive lamps with high power factor

The AL1663 and AL1663R single-stage dimmable LED controllers introduced by Diodes Incorporated support flyback and buck-boost topologies to provide primary-side regulation that achieves an accurate constant-current output without requiring opto-couplers and secondary control circuitry. Operating at up to 150W and featuring multiple dimming options, these controllers provide versatile and cost-effective drivers for LED backlighting, smart LED lighting and general-purpose dimmable LED lamps. High efficiency and low EMI result from operation in boundary-conduction mode with valley-switching control, which further ensures the devices maintain high power-factors with low total harmonic distortion under universal input-voltage conditions. The use of primary-side regulation simplifies design and lowers total BOM component count and cost. They are both also characterised by low start-up current and low operating current, and integrate multiple protection features including over-voltage, short-circuit, over-current and over-temperature. Analog and digital dimming modes are supported: The AL1663R has a single dimming pin that will accept either an analog signal between 0.3V and 2.4VDC or a digital PWM input when connected with a suitable input capacitor of several hundred nF. The AL1663 offers an additional digital dimming input pin that can accept a high-frequency PWM signal and provides built-in PWM-to-DC conversion.