Bleeder-less LED driver ICs reduce BOM count by 40%

Article By : Carolyn Mathas

The ICs provide up to 22W without the use of a heatsink and are packed into a very small SO-8 footprint.

Power Integrations has unveiled bleeder-less and robust LED driver ICs that target bulbs, tubes, and fixtures. Its name is a mouthful (the LYTSwitch-7 single-stage, non-isolated, TRIAC-dimmable buck topology LED driver IC family), but most importantly, it reduces BOM count substantially. That count, moves from approximately 36 parts for an ordinary dimmable LED driver board to only 20.

Central to the ability to reduce component count is its treatment of heat. In this solution, an internal 725V MOSFET provides high withstand performance in the case of surges while the bleeder-less design does not produce wasted heat, yet features high TRIAC compatibility. The ICs provide up to 22W without the use of a heatsink and are packed into a very small SO-8 footprint.

Instead of bleeders, the ICs use simple, passive damping for TRIAC management and a single winding inductor. The dimming solution features a wide dimming range and monotonic dimming response. Efficiency is greater than 86%, which is an improvement of approximately 2% over other dimmable products.

Protection is obviously an important factor and this product provides multiple layers of protection. For example, key to this design is thermal foldback with end-stop shutdown for protection at very high ambient temperatures, which reduces current flow and dims the lamp. Protection also extends to open- and short-circuit conditions, input and output OV, overcurrent, and SOA.

The LYTSwtch-7 family targets single-stage, high PF, constant current LED dimmable applications from 4 to 22W. The MOSFET features a variable on-time CrM controller resulting in low turn-on losses and reduced cost of output diode.

LYTSwitch-7 IC samples are currently available. The ICs are priced at $0.33 per unit in quantities of 10K. There are two reference designs that are available for download from the Power Integrations website.

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