Project 450 - 7W Blue Laser Constant-Current Buck Driver

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loneoceans
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Project 450 - 7W Blue Laser Constant-Current Buck Driver

Hello BLF,

Hope this project isn't too off-topic since this is a laser project, though I think it's still relevant since it's just as capable of driving LEDs. I had some time to do a short post about this project from the end of 2018. Thought some folks here may be interested in. 

Here's what I'm calling Project 450 - a compact, simple, fully-integrated laser platform.

[Update - a small update with Project 450 - the copper block housing was changed to a much higher quality aluminium housing. Batteries were also upgraded to one of the best 16340 cells]

This project currently incorporates a 7W NUBM44-V2 450nm blue laser diode, which comes in a TO-5 can package, and as of writing, is currently the most powerful available visible wavelength laser diode.

 

This project focuses specifically on the design and development of the drive electronics in order to safely drive a constant-current load (such as this diode, or any LED for that matter), and is therefore applicable to all sorts of constant current loads such as LEDs for flashlights.

I would like to make it abundantly clear that I do not advocate the use of these kinds of laser diodes at these power levels since they are extremely dangerous and any mistake will lead to irreversible eye damage. I hope this project will be a good educational resource; please proceed reading responsibly. Laser goggles are always used (in this case a proper 5+OD for the wavelength googles are always worn whenever operated).

This project has two main aspects - an integrated, compact, single-PCB platform designed to be mounted on an aluminium extrusion as heat-sinking, and a 12A-capable true constant-current synchronous buck converter.

 

Integrated Platform

The integrated PCB measures exactly 50 x 100mm, making it fairly compact.

Power is supplied via two 16340 batteries, which essentially dictates the size of the product. In this specific scenario, the maximum drive current is only 4.5A at about 4.7V (~21W), and maximum load current on the cells is about 3A. As a result, the fairly mid-range quality EBL 16340 cells will suffice, though will be upgraded to Vapcell 16340s in the future, which will easily handle over twice the load. 

For convenience, there is a charging circuit on board, which allows charging of the cells via micro-USB at 700mA. On board circuitry boosts the 5V from USB and charges the 2S battery via a dedicated Li-ion charging IC. For most 16340 cells, this results in a roughly 1 hour charge time from flat. 

An Atmel microcontroller handles the entire system for various kinds of events. Here are a few features:

  • Security Safety interlock requiring secret code to be entered via switches before system unlocks, impossible to turn on in a bag 
  • Constant current control with 4 programmable power modes
  • Battery monitoring and low voltage cut-off
  • Charge management
  • Error codes via a total of 5 colourful LEDs

For heat-sinking of the diode, the switching regulators, and the battery charger, the entire PCB only has components on one-side, with exposed ground pads on the bottom. This PCB is then screwed onto a milled aluminium baseplate. 

To prevent shorts, holes are milled into the baseplate for through-hole legs to sit in. A kapton sheet was then laser-cut to insulate all other parts, and thermal paste was then applied to the exposed ground copper pads. 

A cutout allows the diode, housed in a solid copper mount, to be attached directly to the baseplate. 

 

Synchronous Constant-Current Buck Converter

In order to drive the diode safely, a current-regulated driver is required.

There are several that exist today, the most powerful of which is the BlackBuck 8M Rev 3 by x-wossee. This is a  7-12Vin 1-8A constant current buck driver, using the IR3475 10A integrated SupIRBuck regulator. While a nice design, I thought I'd go for something with a little more power capability (not that we would need it). My original thought was to go with the TPS548D21, a 40A fully integrated regulator, but that's too excessive (and expensive), so I settled for a sensible 12A design instead, having about 50% more power handling capability than the blackbuck 8M.

The final design allowed me to layout the buck converter in a very symmetric way, which brings a tear to the eye! No consideration was made to make the layout as compact as possible, since the PCB had a lot of space. However, the main buck converter portion is very compact, and can likely be made much smaller for use in say flashlights or smaller hosts.

 

Testing & Results

Testing was initially done with a Cree XML2 LED to ensure correct operation and proper current regulation, before it was replaced with the laser diode. Frankly, it made a very nice, cute flashlight, so maybe I'll make this into a lamp in the future... To be honest I will probably not use this much at all since it's too dangerous, so it will likely have an alternate life as a desktop lamp. Smile 

Power levels were set to be (fairly arbitrarily):

  • Threshold
  • Bright (0.5W output) at ~600mA
  • Powerful (2W output) at ~1.35A
  • Turbo (7W output) at ~4.5A

Finally, the system was put together with a stock glass lens on the diode. The housing allows for a standard M9-0.5mm thread lens, which will be likely replaced in the future with a better lens. For now, a AR coated 405-470nm lens is used. 

The result was as expected and the system runs very well. More result images to come soon later.

For more information, here's a detailed write-up: http://loneoceans.com/labs/project450/ 

Hope this was slightly interesting.

Cheers

www.loneoceans.com/labs/

- Next-gen Switching Drivers: Lume X1 and Lume1
- High Power Boost Drivers: GXB100 GAN 100W, GXB172 17mm 50W
- Older: GXF22, GFS16, GXB17 & GXB20

Edited by: loneoceans on 10/07/2019 - 17:53
loneoceans
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[More to come soon]

 

Here's a quick photo of the beamshot. It's slightly difficult to capture how it looks like since the entire room lights up blue, so here's it running at low power setting. Some water droplets were sprayed in the air to make the beam more visible. 

www.loneoceans.com/labs/

- Next-gen Switching Drivers: Lume X1 and Lume1
- High Power Boost Drivers: GXB100 GAN 100W, GXB172 17mm 50W
- Older: GXF22, GFS16, GXB17 & GXB20

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loneoceans wrote:
I would like to make it abundantly clear that I do not advocate the use of these kinds of laser diodes at these power levels since they are extremely dangerous and any mistake will lead to irreversible eye damage.

(emphasis mine)

This is why I've resisted the lure of high powered lasers. As much as I want to set things on fire from a distance...

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Scallywag wrote:

loneoceans wrote:
I would like to make it abundantly clear that I do not advocate the use of these kinds of laser diodes at these power levels since they are extremely dangerous and any mistake will lead to irreversible eye damage.

(emphasis mine)

This is why I've resisted the lure of high powered lasers. As much as I want to set things on fire from a distance...

For me, it's just that I don't have money to spend on lasers, nor the electronics expertise to scrap one out of old Blu-Ray drives that I have around. I'm not very worried about eyes, because laser protection eyewear does exist, and should always be used. cool

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Scallywag wrote:

loneoceans wrote:
I would like to make it abundantly clear that I do not advocate the use of these kinds of laser diodes at these power levels since they are extremely dangerous and any mistake will lead to irreversible eye damage.

(emphasis mine)


This is why I’ve resisted the lure of high powered lasers. As much as I want to set things on fire from a distance…

7w set fire to the space station lol.
Ive never seen a 7w lasrer diode for sale any where. If you take a blueray laser they are around 1+ watt i think.
Another awesome project loneoceans!

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Great work resulting in a nice compact device! Smile

I own a 3W blue laser with a driver for it, it was a deal at the time. It is way bigger than your beautiful build. I have tried it only once (with safety goggles on) to check the working, but never again because there is simply no other use for me than playing and that is exactly what is a bad idea with powerful lasers.

So me I stick to low power fun lasers and to flashlights, but still: very nice project! Thumbs Up

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Nice but scary.

contactcr
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$100 laser diode that’s used with wood engraving? i’m out Steve

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loneoceans this is another beautiful project!! I have no experience with laser but I like your idea of putting everything on one board.

I see great possibility that you use the same idea to build a buck driver for flashlight! This seem like a 12A buck driver to me, if you can make 12A 2S buck driver in 17mm, i think a lot of people will want to buy it! Maybe it exist already but I do not know.

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7w? wow. This is a 1.5w with a G2 lens, and is very powerful. 2×18350, or 2×16340’s.

Not sure how you handle the heat with 7w though. This 1.5w gets hot pretty fast.

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Wait, you are going to build a driver for a 7W laser.

If it’s around 20% efficient, then you’ll need to provide 35W of power.

That’s on the level of an XHP70.2 with the die size of an 1mm2 White LED.

My very own high current Beryllium Copper springs Gen 3:
http://budgetlightforum.com/node/67401
Liitokala Aliexpress Stores Battery Fraud: http://budgetlightforum.com/node/60547

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I can foresee something like this in the near future…

LOL

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BlueSwordM wrote:
Wait, you are going to build a driver for a 7W laser.

If it’s around 20% efficient, then you’ll need to provide 35W of power.

That’s on the level of an XHP70.2 with the die size of an 1mm2 White LED.

loneoceans say for 7w light output he driving with about 21w power in! it seem like this driver can do 50w power, so this is why i suggest to make a very powerful buck driver for flashlight using same design!

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Flashlight driver doesn’t sit on a thick piece of copper though and it wont fit on 17mm. I’m sure there is some that can be adapted to flashlights though

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I wish it were harder to imagine this kind of high powered blue or violet laser getting into the hands of a nutcase.

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djozz wrote:
(…)there is simply no other use for me than playing and that is exactly what is a bad idea with powerful lasers.

Exactly my thoughts.
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hank wrote:
I wish it were harder to imagine this kind of high powered blue or violet laser getting into the hands of a nutcase.

Could just as easily be used to disable a nutcase, though. And from a nice safe distance.

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Lightbringer wrote:
hank wrote:
I wish it were harder to imagine this kind of high powered blue or violet laser getting into the hands of a nutcase.

Could just as easily be used to disable a nutcase, though. And from a nice safe distance.

Big Smile Evil “Ballz-eye!”
teacher
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Lightbringer wrote:
hank wrote:
I wish it were harder to imagine this kind of high powered blue or violet laser getting into the hands of a nutcase.

Could just as easily be used to disable a nutcase, though. And from a nice safe distance.

+1Thumbs Up

The only defense against a bad guy/nutcase with a high powered blue or violet laser is a good guy with a high powered blue or violet laser.

Hopefully the ‘good guy’ will have proper eye protection and the ‘bad guy’ will not.

If the bad guy does have eye protection, go immediately to Plan B…..
……….. the Pb & Cu solution.

You never know how a horse will pull until you hook him up to a heavy load./"Bear" Bryant 

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I was thinking about situations like the nutjob in Nebada Las Begas during that concert that used the dreaded bump-stock to do his nasties. Okay, so everyone’s pinned down, you can’t shoot back even if you were packing (at risk of peppering a bunch of innocently-occupied rooms in the process), but one good look at where the bozo’s shooting from, whip out Ol’ Blue, and give him a few multi-watt flashes to sear his retinas, and he won’t be shooting anyone except purely at random. And then won’t be able to escape without feeling his way out with a white cane.

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Lightbringer wrote:
I was thinking about situations like the nutjob in Nebada Las Begas during that concert that used the dreaded bump-stock to do his nasties.
Yeah… that was bad. Amazing it disappeared from the news so fast too.

“The dreaded bump-stock”…. Big Smile Big Smile I’ll have to assume that is sarcasm. Beer
A bump-stock is good for nothing but to play with for the most part. If your trying to really hit anything specific after the second shot…. good luck unless you are highly trained & lucky. It’s more of a ‘pray & spray’ device.

Heck, you can do the same thing with a rubber band or a belt if you know what you are doing. Wink

Lightbringer wrote:

Okay, so everyone’s pinned down, you can’t shoot back even if you were packing (at risk of peppering a bunch of innocently-occupied rooms in the process), but one good look at where the bozo’s shooting from, whip out Ol’ Blue, and give him a few multi-watt flashes to sear his retinas, and he won’t be shooting anyone except purely at random. And then won’t be able to escape without feeling his way out with a white cane.
That could possibly work well…. Thumbs Up
But, on the other hand, if you have located where the “bozo” is; Pb & Cu could work well also.

Hope we never have to find out about either…. Beer

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Lightbringer wrote:
(at risk of peppering a bunch of innocently-occupied rooms in the process)

Just to repeat, then I’m out (don’t want it to get too “political”).

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Lightbringer wrote:
Lightbringer wrote:
(at risk of peppering a bunch of innocently-occupied rooms in the process)
Just to repeat, then I’m out (don’t want it to get too “political”).
Political??? Ok??? Facepalm

Just like if you use said laser… you hit your target or blind a bunch of innocent people…. right??

The same thing applies to Pb & Cu…. hit your target, whatever it may be.

With either one, you do not do it unless you know you can hit what your aiming at.

I’ll be out to I guess…
………..would not want to offend or tip off any potential bad guys. Wink

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teacher wrote:
:

Just like if you use said laser… you hit your target or blind a bunch of innocent people…. right??

Questions (not being sarcastic and also not suggesting it’s a good idea either):
Would the buildings glass not stop said laser from hurting people behind it (so only the shot out window rooms occupants were at risk)?

Would the buildings glass reflect the laser and have it still be powerful enough to do damage to people still on the ground?

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Quote:
Class 3B
LASER RADIATION
AVOID EXPOSURE TO BEAM
CLASS 3B LASER PRODUCT

A Class 3B laser is hazardous if the eye is exposed directly, but diffuse reflections such as those from paper or other matte surfaces are not harmful. The AEL for continuous lasers in the wavelength range from 315 nm to far infrared is 0.5 W. For pulsed lasers between 400 and 700 nm, the limit is 30 mJ. Other limits apply to other wavelengths and to ultrashort pulsed lasers. Protective eyewear is typically required where direct viewing of a class 3B laser beam may occur. Class-3B lasers must be equipped with a key switch and a safety interlock. Class 3B lasers are used inside CD and DVD writers, although the writer unit itself is class 1 because the laser light cannot leave the unit.

Class 4
LASER RADIATION
AVOID EYE OR SKIN EXPOSURE TO
DIRECT OR SCATTERED RADIATION
CLASS 4 LASER PRODUCT

Class 4 is the highest and most dangerous class of laser, including all lasers that exceed the Class 3B AEL. By definition, a class 4 laser can burn the skin, or cause devastating and permanent eye damage as a result of direct, diffuse or indirect beam viewing. These lasers may ignite combustible materials, and thus may represent a fire risk. These hazards may also apply to indirect or non-specular reflections of the beam, even from apparently matte surfaces – meaning that great care must be taken to control the beam path. Class 4 lasers must be equipped with a key switch and a safety interlock. Most industrial, scientific, military, and medical lasers are in this category. Medical lasers can have divergent emissions and require awareness of nominal ocular hazard distance (NOHD) and nominal ocular hazard area (NOHA).20

Pretty sure the power and wavelength would put this far into Class 4, meaning it can mess your day up with even a diffuse reflection

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Makes me laugh that they’ve made it illegal to use & export above 5mw lasers but you can have as many guns as you like.

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Nev wrote:
Makes me laugh that they’ve made it illegal to use & export above 5mw lasers but you can have as many guns as you like.

Obvious troll since UK has some of the most strict gun laws

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I was talking about USA
I have a 50mw ,37mw & 17mw lasers , they had to be sent on the QT.

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Nev wrote:
I was talking about USA

I know, mind your own business Smile

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contactcr wrote:
Nev wrote:
I was talking about USA
I know, mind your own business Smile
I will if you will , posted with love , I seem to have acquired my stalker Troll back Wink
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Discussions about gun control derail in seconds, better not to go into that.

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