LED driver cuts component count, hits volume LED-lighting cost targets
LYTSwitch-0 is a new series of devices within the LYTSwitch family, offering a combination of simplicity, reliability and efficiency. LYTSwitch-0 ICs are intended for cost-sensitive, non-isolated, non-dimmable GU10 bulbs and other space-constrained bulb applications. The earlier, more fully-featured devices in the series – that include dimming – now become “ LYTSwitch-4”.
LYTSwitch-0 will enable LED bulb manufacturers to hit key price points, PI says, by offering a much smaller total component count, with low-cost components, “13 additional components, when typical designs are using 30-40, and we have seen up to 70”. The driver has to account for 35-40% of the cost of the bulb, and in the coming months that total cost will be in the $6-7 region. Also, the company says, to avoid the poor customer experience of CFL lamps, US legislation now specifies a guaranteed minimum lifetime, so manufacturers cannot afford to use low-grade components; a low component-count design is the only option.
LYTSwitch-0 devices feature efficiencies of more than 90% and deliver constant current with better than ±5% regulation in typical applications – “typically 2%”, according to a spokesman and “few [other products] even achieve 5%”. Power factor is greater than 0.8 at 115 VAC and 0.55 at 230 VAC, meeting all worldwide requirements and specifically ENERGYSTAR V1 draft 3 consumer lighting standards for North America and Ecodesign Directive Lot 19 part 2 for Europe.
The device uses a 700-V FET thus avoiding any need for in-rush current protection; all other applicable protections (temperature, over-voltage, over-current) are integrated, and the chip is self-powered avoiding the need for a complex inductor with multiple windings. Multiple operating modes – buck, buck-boost, flyback and boost – are also supported. Low heat dissipation avoids the need for potting or heatsinking; a typical application schematic does show an electrolytic capacitor on the device output (47 µF/63V) but PI says that configurations with all-ceramic capacitors are possible; and that the low heat dissipation limits temperatures in the driver and should extend the life of an electrolytic.
Key applications include low-cost LED light bulbs such as GU10 and candelabra styles. RDR-355 describes a 6 W non-dimmable LED driver – see www.powerint.com/sites/default/files/PDFFiles/rdr355.pdf
LYTSwitch-0 IC is sampling in SO-8 and DIP packages; the device costs $0.29 (10,000).
Power Integrations; www.powerint.com/en/products/lytswitch-family/lytswitch-0
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