Help with LED switcher supply - Page 3 - Electronic Circuits Projects Diagrams Free

audioguru · 11th December 2006, 02:55 PM

Guess who bought Lumileds and makes Luxion bright LEDs?

justDIY · 11th December 2006, 03:03 PM

Philips co-founded lumileds with HP (aka Agilent). Only recently did Philips buy-out HP's stake in the company, making lumileds wholey owned by Philips

edit: typo!

audioguru · 11th December 2006, 03:15 PM

I have some very nice HP and Agilent LEDs. I didn't know Philips were involved with them.

technogeek · 11th December 2006, 05:59 PM

Quote:

Originally Posted by justDIY

I seem to recall seeing diagrams from lumileds or perhaps philips (for their xitanium driver) showing suggested wiring of series-parallel arrangement. The series strings were wired in parallel across the supply, and crossbars were used to link the two strings between each LED.

I supposed the purpose of the crossbar was to normalize voltage on the two strings, preventing any one abnormal led from causing a current hogging scenario.

I'm searching for that info again, will post the link when I find it.

edit: looks like LuxeonStar.com summarized the application note here:
http://www.luxeonstar.com/xitanium-usage.php

Wow! Now that's strange!

So if I were to create a 1.4A power supply, and used two strings of 20... what are the chances each would get exactly 700mA? Aaaand, how many crossover connections should there be? One for every 5 LED's?

Looking at their datasheet- http://www.luxeonstar.com/xitanium-120v-drivers.pdf

they seem to prefer low voltage high current outputs, with 6 LED's per branch..... Interesting.

edit- seeing as how I already ordered parts, I plugged the numbers in again for double the current. The only things that changed were the input capacitor trippled in size, and the inductor halved. All of the currents/voltages are still well within the limits of the parts I chose. So, what would happen if I used a 1.8mH inductor in place of a 0.9mH inductor? Anything? Less current ripple maybe?

Oh, and my sense resistor halved.

justDIY · 11th December 2006, 06:40 PM

using a larger inductor offers no benefit, and as far as I know, no major drawbacks. However, there is a drawback that the larger inductor may not be rated for your newly calculated peak current.

Oznog · 11th December 2006, 07:37 PM

I prefer the Lamina devices myself. Outrageously flat and an electrically insulated backing of pretty decent size.

I noticed that the 10mm LEDs have evolved into ones with HUGE ratings. I ordered some off a guy on eBay with a 150,000mcd rating over 30 degress! I mean, holy crap! They use multiple dies in the package, which precludes a tight focus. I'm still waiting, they came from China so it's expected to take awhile. I only paid $5.62 for 5 of them though.

technogeek · 11th December 2006, 09:40 PM

Quote:

Originally Posted by Oznog

I prefer the Lamina devices myself. Outrageously flat and an electrically insulated backing of pretty decent size.

I noticed that the 10mm LEDs have evolved into ones with HUGE ratings. I ordered some off a guy on eBay with a 150,000mcd rating over 30 degress! I mean, holy crap! They use multiple dies in the package, which precludes a tight focus. I'm still waiting, they came from China so it's expected to take awhile. I only paid $5.62 for 5 of them though.

What wavelength? 32 lumens is about the equivalent of a 1W or 3W LED depending on wavelength...

justDIY · 11th December 2006, 09:46 PM

the candella is a worthless unit (and method) of "measurement"

depend on lumens or mw or some other more reputable method

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11th December 2006, 03:03 PM	(permalink)
justDIY	Philips co-founded lumileds with HP (aka Agilent). Only recently did Philips buy-out HP's stake in the company, making lumileds wholey owned by Philips edit: typo! __________________ If you don't have a planet, what good are gold bars? want to contact me directly? gmail gordonthree check out my project website: http://projects.dimension-x.net Favorite numbers: 09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0 Last edited by justDIY; 11th December 2006 at 03:55 PM.

11th December 2006, 03:15 PM	(permalink)
audioguru	I have some very nice HP and Agilent LEDs. I didn't know Philips were involved with them. __________________ Uncle $crooge

11th December 2006, 06:40 PM	(permalink)
justDIY	using a larger inductor offers no benefit, and as far as I know, no major drawbacks. However, there is a drawback that the larger inductor may not be rated for your newly calculated peak current. __________________ If you don't have a planet, what good are gold bars? want to contact me directly? gmail gordonthree check out my project website: http://projects.dimension-x.net Favorite numbers: 09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0

11th December 2006, 07:37 PM	(permalink)
Oznog	I prefer the Lamina devices myself. Outrageously flat and an electrically insulated backing of pretty decent size. I noticed that the 10mm LEDs have evolved into ones with HUGE ratings. I ordered some off a guy on eBay with a 150,000mcd rating over 30 degress! I mean, holy crap! They use multiple dies in the package, which precludes a tight focus. I'm still waiting, they came from China so it's expected to take awhile. I only paid $5.62 for 5 of them though. __________________ I thought what I'd do was I'd pretend I was one of those deaf-mutes.

11th December 2006, 09:46 PM	(permalink)
justDIY	the candella is a worthless unit (and method) of "measurement" depend on lumens or mw or some other more reputable method __________________ If you don't have a planet, what good are gold bars? want to contact me directly? gmail gordonthree check out my project website: http://projects.dimension-x.net Favorite numbers: 09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0