Philips Lumileds (this site's sponsor) has been making a push in mid-power LEDs. First of a number of announcements expected this month is for this high-voltage part.
The HV in the product name designates a high voltage; versions are available that operate at 24V and 48V. The higher voltages, closer to the input line voltage, can result in smaller power supplies and drivers, decreasing costs and also potentially increasing efficacy.
Lumileds claims that a driver for a 3535-HD could have a component count of 20, in contrast to standard drivers that may consist of as many as 50 parts. The high-voltage LEDs are therefore suitable for applications in which space is most constrained, including downlights and retrofit lamps.
The mid-power parts don't (yet) achieve the levels of efficacy reached by high-power LEDs, though that is Lumileds's stated goal over time. A 4000K 3535-HV, driven at 24 volts and 20 mA, produces 120 lm at an efficacy of 125 lm/W at a CRI of 80, when characterized at 25°C. Lumileds's press release for the 3535-HV claims that by the end of March the company will have announced 185 lm/W mid-power parts.
The LEDs are offered in 3- or 5-step color bins, as many high-power discrete LEDs are. Lumileds is aiming for increased confidence in the quality of these mid-power components, trying to dispel the impression that such lower-priced components won't exhibit the longevity or color stability of proven high-power LEDs.
Last month LEDs Magazine ran a piece, authored by Cree executives, exploring some of the mechanisms for lumen depreciation and especially color shift in plastic-packaged LEDs. Philips Lumileds hasn't talked about the packaging in its new mid-power LEDs, and it will be interesting to see how the company addresses these concerns. Part of the reason mid-power parts are lower in cost is that they tend to use plastic in place of ceramic packaging.
— Keith Dawson 
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