LPF Site Supporter
- May 9, 2011
Yea they are wired in series so for sure 30V-36V is probably the drop and I would bet they don't go over 3A. They have to be able to compete with the life of LED sources to be competitive in the market so it means running them way below their potential or where previous generation dodes which usually were only rating a life of 500-5K hours. You can look at the power tests and see the difference in the percentage back of foldback that is on the datasheet for the rated currents on previous generation diodes compared to thess. Also maintaining specific wavelengths is very important as they tweak the ratios trying to get the best color balance with the limitations of the system which has been hit and miss for hybrid as you have to have the same blue for the blue and the conversion of blue to green which I think is one reason for after a bit having two types in the array(a-type m-type). Some go for all laser color conversion which probably gives a little better control of the color but more loss weather they pass the blue or convert the blue to slightly different blue as well as converting the green and red from the blue. Anyway current and temp is important to maintain that especially in an environment where you may run it continuously for hours or event days. I remember after just 20 minutes you could fry and egg on the sink in an A140. Burnt the crap out of my hand and not sure if that was a engineering feat for the small form factor units that has improved and is not as much of an issue in the larger units.If I was going to drive 9 x nubm44's I would regulate the current not the voltage so I would regulate @ 4.5a and make sure there was 42 volts available although it would likely draw closer to 41v @ 4.5a
Typically I run a nubm44 at 4.5a and it will draw about 4.5v however the factory data projector drives at a lower current that's sustainable with active cooling, it also adjusts for demands and compensates for wear over time, that's why we can push them so hard, there is a lot of headroom built in.
Anyway if you regulate current the diodes will draw the voltage they need, so you want your driver to be able to supply it, also laser diodes don't like spikes or noise so you wouldn't want to use just anything, actually a linear would make sense for 9 x nubm44's in series and would be pretty easy to make.
The only way I see that being possible is with inductive kick. It would be reproducible with a bench power supply, since the internal resistance there is effectively zero. All lengths of wire are inductors, although small.Recently decided to look into it and found some tests showing a loading voltage surges for 2S and 3S packs can be huge like 20V for 3S packs due to near zero internal resistance.
Oh yes on my cheap mastech supply I was killing drivers by connecting them with the supply set above 10V which I only started having issues with when the newer higher power diodes came along as I use 12V with the 3.5A and over as I am lazy and don't want to change the jumper all the time on my test load or have to remember which setting I have it on when I put a new driver on it as most the time I am setting drivers I try to do things efficiently so I will take a block of orders and see the number of drivers of different types and what currents to do them all like an assembly line having them ready for the builds or if I have a large order where I am setting many many drivers I want to just book through them only pausing when my massive test load needs some cooling.OK, challenge accepted I will build it and ping the hell out of my NUBM44 with a power supply cycling on and off for days to see.
E: Anyone know a shortcut for a PCB already made for this regulator for CC?
For 4.5a the resistor would be 0.2667 the cap is not needed AFAIK
The input capacitor is a good thing. Mostly it will work without, especially when powered from a battery with short leads and such. But it doesn't do anything bad here either, and can prevent problems with oscillations - just leave it in as long as you have physical space for it.
Also make sure you get the proper resistors. As drawn, the single 0.2 one drops 0.9 volts at 4.5 amp, dissipating 1.8 watts. You'd need a 2 watt resistor, but make sure you do not use wire wound resistors, their inductive nature causes problems. So make sure it's a film type.
There are more ways to get to about 2.66 ohms though. As the whole combination dissipates a whopping 1.25 volts x 4.5 amps or 5.6 watts you have some choices to make. One would be to use 0.4 watt metal film resistors. 14 3.9 ohm resistors in paralel would give you the value needed, and be within their power rating as well.