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Old March 19th, 2008, 12:07 PM   #20
General Lee
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Quote:
Originally Posted by Haggar View Post
When we have heat specific, we can and do use buck regulators.

Thing is that for high power (InGaN) parts, we can't use current control for changing intensity, only the PWMing. (A typical LED circuit would have a PNP transistor no the high side for PWM control, the LED, then current limiting resistor, then an NPN switch on the low side for on/off control. ).

Resistors are binned at a specific current, which is the only point their characteristics are guaranteed, usually. What happens is that as the current changes, the X-Y color coordinates change as well. Its especially noticeable in the whites, and we have tight specs for the color coordiantes.

But, in the production world, cost is key. one of the projects I'm doing now, I took 3 cents out per LED, which at our volumes saves us $1.7M per year, so little things add up. I think my current prorgam is using 41M LEDs per year...
Yeah, I don't mass produce, so I just shoot for quality.
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