I would like to hear your ideas. I’m making a similar light bar that uses six xhp70. And need reliable devices to run the led just like the OP
Well for me, i want to keep it simple as possible, and to me that means using a ready made electronic driver with modes at least and on this unit that i just found it has the bonus of having over temperature, short circuit, etc. If it can handle a torture test that i throw at it, then it is a winner.
But if i dont think it is any good then i will have to get creative, or get a custom mcpcb made by Leo.
Depends on how much “headroom” (difference between Vf and Vbatt) you have. Too small, and you need an efficient low-dropout regulator. Too big, and you need efficiency like a buck regulator. Control circuits can be quite small and use little power, while pass elements need to shed heat and need to be mounted on something like a metal chassis. TO220 cases need to be inside, as the pins are exposed. TO3 and TO66 cases can be mounted on the exterior, as long as it’s properly insulated/weatherproofed (think of a guitar amp).
The LM340 can be used as a current regulator, not just a voltage regulator. Beefy resistors can burn off some excess power.
If it’s switching regs you need, places like Maxim probably even have “evaluation kits” that include the IC and other necessary goodies on a small PC board.
The more details the better…
And don’t overlook “outside the box” solutions like gutting car-usb chargers. Meant to plug into a lighter socket (12V in), and spit out regulated 5V (easily dropped to 3.xV for an LED), probably as cheap as dirt when mass-produced in the brazillions of pieces.
Sounds like a good candidate for my “outside the box” suggestion above. 
Well it appears that you know your stuff, however, I really don’t want to mess with a bunch of homemade custom power supply circuits as these are going into light bars that people are going to purchase. Those car USB power supplies are unreliable too, IMO. I consider myself a naturally “outside the box” thinker and I have considered many different options, but the main point is to keep things simple and reliable. Keep the ideas coming, it is going to help me.
Does Leo’s company make integrated regulator circuits on their boards?
I agree with Lightbringer, look into non-driver solutions. I have been reading the thread but I don’t remember all the details. Are all the LED’s in a bar driven at the same time? Whats your max current expectation? Could you use one of the DPS5015 Power Supplies or one of its siblings that Texas_Ace found on AliExpress to drive the bar? I realize that the UI has a lot of stuff that you don’t need in it, but perhaps you and RD Tech could work out a custom solution based on the same technology. It would be very cool to be able to simply turn a knob to adjust the current limit on the supply which would ramp the LED output.
Eg, for 3A max, you could use something like this, directly:
which’d take 12V with up to 35V spikes (load dump), and you’d adjust the voltage to feed an LED and ballast resistor.
A 6V LED (XHP-70/-90) could then get up to 18W. Stick a 1Ω 10W resistor in series with it which you could predict would drop 3V at that 1A current. So you’d set the voltage to 9V.
The ballast resistor removes some of the sensitivity to voltage that the LED has, making adjustment less critical.
Ideally, you want a current regulator vs a voltage regulator, but they might be harder to find and not as cheap.
You’ve sure come a long way in researching your parts list. Please dont give up!
If you’re still looking for a custom high powered automotive LED driver, designed to handle the high voltage spikes from an alternator, check out my light bar thread. These do 13.5A @ 14.9V and are provisioned for variable dimming via a potentiometer, thermal protection for the driver as well as remote thermal sensor for the heat sink (current is reduced if the sink or driver becomes overheated).
Thanks for the link Flashpilot, but I have some drivers en-route to me for testing, a boost driver with thermal and short-circuit protection, from Sure Electronics.
Here is my revision of the light bar… I decided to simplify the design and go with the superior flood optic, and also it will have 5 OR 6 spot optics. Total Candela output (with 6 Spots) moves to ~580,000Cd from 380,000Cd, and 25000 LED Lumens from 20,000 LED Lumens.
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Really excited to see how this shakes out!
You really opened a whole new style on designs with the XHP series. In sets of 2 or 3 for side and rear mounting. Whole single row bars with maybe 6 to 20 large LED’s without the goofy 2 high stacked xpg clones in 100 LED Chinese light bars. LOOKING GOOD!!
Oh it’s going to be good. I am a bit behind with my budget at the moment so it will be be in the new year before i get a prototype built. I athink i am going to make an external driver enclosure, it saves trying to cram everything inside the bar, and simplifies wiring as only a 3 wire is needed into the bar. I lose thermal protection, however.
Well these things are just plain big, bigger than I expected them to be, but that is okay as I will be making an external box enclosure for them, and in this case, they are no longer too big. 4 times the footprint of the old drivers, however not a fair comparison as these are rated for 50 watts and the Russians are ‘designed’ for 30 watts, I was pushing 38 watts through them, they make a buzzing ‘switching’ noise though.
Dimensions are 3 inch x 2 inch and 3/4 inch tall or 50mm x 75mm and just under 20mm tall.
I will rig them up and test them out to see how they handle 48 hours of torture. :smiling_imp:
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Well I tried one of the drivers on the light bar for a bit, works great… went to wire up another in parallel, and poof went the second one. Why? I checked and checked my wiring (pretty simple!) for reverse polarity but I found no issue.
I need someone with more knowledge than me on this, can you drive two current regulators in parallel? I have done it no problem with the russian 3 amp drivers, in fact a 3 amp and a 2.4 amp driver in parallel. I know you can’t wire two voltage regulators in parallel, such as a computer PSU as there is always a difference in voltage between the two units which makes it non-compatiblein this way, but you can wire them for series operation. I think this is opposite when we are dealing with a current regulator such as an LED driver.
My conclusion: Either you cannot wire two boost regulators in parallel for some reason that I fail to see, or this was simply a dud driver and I want nothing to do with these then…
Transistor right in the middle of the board went poof.
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It is not good idea to parallel output both on buck and boost circuits.
Once you get the drivers figured out, would you consider potting them for vibration resistance? It seems like this would be an optimum application for that, otherwise all those little caps would just wiggle and fall off sooner or later.
That is exactly what i will be doing. Or using a thick silicone conformal coating. I might just want to get the custom made circuited DTP mcpcb board, that would be nice at this point.
Driver has been running 4 xhp-50 6V in series for 12 hours now. Temps took about an hour to hit equilibrium, with the inductors being the hot spot of 60+ C (140+F).
I am tempted to test their 100watt 3 amp BUCK driver, looks to be MUCH small (half the size), same price, but it would be running at less than half the rated output, might help for temps… and obviously packaging. The light bar just won’t have the 100% power output at any voltage. We will see.
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You probably shouldn’t parallel switching regulators unless they specifically mention that outputs can be paralleled.
Looks like only the MOSFET is damaged though, so if you replace it it may be salvageable.
Are you being flexible on LED selection or driver modes?
I saw the link to DIWDivers led driver, but also note his last forum activity was a while ago… His driver seemed very good, in terms of both power output and affordability.
Very interested to see where the rubber finally meets the road.
For a ~$400 outlay, cast my vote for 4k color temp and either/or Hi/Low with both flood and spots, or select flood/spot/flood+spot.
Amazing work, guy. I love projects like these.