Design Con 2015

Leeper tears down Philips L Prize LED bulb

-March 19, 2012

Doug Leeper got his hands on a Philips L-Prize bulb and promptly tore it down.

The L-Prize bulb (10W, 940lm) is quite a bit different from the first of their secondary phosphor bulbs (12.5W, 800lm) in that it combines red LEDs with the blue. (See EDN’s teardown here, um, only the pictures aren’t displaying just now…) Philips is not the first to do this (think, for example, of Cree’s TrueWhite technology, which tunes the warmth of the white light by kicking in with small LEDs) but it is unusual in that it uses the red with a remote phosphor.

This bulb, which is a replacement for a 60W incandescent, currently sells for $49.95. (More on that in another post.)

Here are Doug’s photos of the LEDs: (Photos are used with Doug’s permission.)

philips-leeper-1.jpg

To see the visual difference between the secondary phosphors, here is a side-by-side comparison of the two secondary phosphor lenses:

philips-leeper-2_sm.jpg

The bulb on the left is the same model used in last February’s EDN teardown, which had only blue LEDs in it. The one on the right is the L-prize bulb, which has the red LEDs along with the blue LEDs, so the phosphor has to be able to respond to, or at least not trash, the red light spectrum.

Like the 12.5W Philips bulb, the L Prize bulb uses a Cypress dimming power control IC series, which Cypress no longer offers. Cypress originally licensed the IP for this series from iWatt, and has now  transferred this part over to iWatt. Cypress will be introducing its own LED power control IC sometime this year.

Some other specs:

philips_leeper-3.jpg

But don’t just look at these few, small versions of the pictures – click on over and see Doug’s complete teardown. Thanks, Doug!

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