Laser driver with 500mA current

Hi,

Can any one help me to make a good laser diode driver or is there any good IC which can drive laser diodes.

We have laser diodes with 200 mW power and 450mA operating current.

I have read that Constant current drivers are the best drivers to drive laser diodes,is that true?

Thanks in advance.

Regards

Have a look at iC-Haus. Also, you need to look at the data sheet of the laser carefully to find out how to drive it. Most low power devices have a monitor diode which should be used to control the laser. That also needs an optical power meter to set up.

Keith.

The voltage across the diode is about 2V and varies a bit with temperature. Because the differential resistance is very low, feeding a diode from a fixed voltage would cause very large variations in current. You say your diode is 200mW and 450mA, this is in pulsed mode, 2V at 450mA = 900mW, so make provision to pulse the diode from square one!
Frank

Thank you very much Keith,

I have made one driver circuit by using " iCHB QFN 24" driver from iC haus. But during my testing 2-3 diodes are failed. So i"m bit worried about the reliabilty of my circuit. I have one optical power meter and i"m setting up the power below the maximum level(80%) also.

You say your diode is 200mW and 450mA, this is in pulsed mode.

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The specification makes sense for a CW laser diode, because usual laser specification is for optical output, not input power.

It is worthwhile contacting iC-Haus. I have had good technical support from them.

Keith.

This may help, there are quite a few constant current laser drivers here. Many are capable of 500mA and greater, several open source drivers as well. Boost and buck designs...

https://laserpointerforums.com/f67/

And

https://laserpointerforums.com/f67/how-laser-diode-drivers-work-explanatory-thread-71513.html

The IC-haus is expensive! I looked at their pricelist and many of their chips were over $8 ea h and that doesn't include any components you will also need or PCBs. Many of the designs on laserpointerforums use the lm3417 or TI TPS6306X chips that cost less than $3 each. In many cases, using dorkbot / osh park, PCBs can be had for $0.50-$1.00 each. Most of the SMT components cost pennies, except op-amps and inductors.

The voltage across the diode will depend on the wavelength of the diode.

IR and red tend to run less than 3v, blue tend to run 4-5v and violet (blu-ray, 405nm) may be as high as 6v.

It is easy to design a constant current driver but you need to choose what is appropriate for the laser. Many have built in monitor photodiodes and should be driven to a specific optical power so a constant current driver would be unsuitable.

Keith

The laser pointer forum I mentioned above has done a great deal of testing and there are some pretty good basic reference points for many of the more common diodes. It is fairly rare to be using diodes that have a built in monitor photodiode at those current levels.

Diodes commonly driven at 500 mW include the 12x 405nm blu ray burner diodes, which can handle 500mW for a reasonably long lifetime and yield 600-750mW of power at these levels. Also, the LPC-826 and less commonly the LPC-836 red 650nm diodes can be run at 500mW and will yield 250-350mW of power at these levels.

It all depends on reading the drive requirements from the datasheet. If the laser has a built in monitor photodiode then you should be using it. You will find monitor photodiodes in lasers up to a few watts but also plenty without them - it depends on the market the laser is intended for and the laser design. I don't think my customers would be happy with my designs if I told them it should have a "... reasonably long lifetime".

Keith

As an additional point, if you are talking about laser diodes designed for CD/DVD drives, you should consider that they have the option to do an in-system power calibration utilizing the dual receiver diodes. Other laser diodes may rely on an initial production adjustment with a power meter.

Of course, if the laser diode data guarantees both reliable operation and sufficient output power with current programming only, you don't need a power measurement.

keith1200rs said:

It all depends on reading the drive requirements from the datasheet. If the laser has a built in monitor photodiode then you should be using it. You will find monitor photodiodes in lasers up to a few watts but also plenty without them - it depends on the market the laser is intended for and the laser design. I don't think my customers would be happy with my designs if I told them it should have a "... reasonably long lifetime".

Keith

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I understand what you are saying. I am making the mistake of assuming this is a hobbyist level project. If you are making something for mass market then you will need to run the diode at a manufacturer rated level.

It would be more helpful if we knew what the OP was using the diode for in the first place.

Yes, the original poster hasn't given many facts other than even with a power meter he is blowing them up!

Keith

For the design of laser driver circuits this application report is very helpful: https://www.ichaus.biz/wp4_fastlaserdriver .

Enjoy your design work!

Very interesting read, thanks!

I did some looking and these are not inexpensive.

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Don't get me wrong, they look very incredible but I know many of the designs we are coming up with are coming in at under $10 per driver and some as low as $5 per driver.

Some of these are admittedly hobbyist level designs, but at the photon lexicon forum, there are plenty of folks using these drivers to run professional laser projectors for very high end laser shows at concerts and the like. I will say this driver looks very detailed and the price is not ridiculously high, but just a bit over target for some apps.

If you are looking for an inexpensive open-source boost driver, (boost from one Li-ion battery) do a google search on "Ben boost" and I think you will be pleasantly surprised.

Here is a direct link...

http://laserpointerforums.com/f67/free-diy-open-source-boost-driver-tested-working-71433.html

At the very least, there are some very smart people there who are working on a lot of different drivers.

http://laserpointerforums.com/f67/

Also, Dr. Lava (Andrew Kibler, Phd) is a bit of a genius in the laser field and as created a very well-received driver that is used by projector professionals as well as pointer hobbyists.

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It depends on the requirements to pick the best solution. Discrete driver are cost effective but have their limitations( more details can be found here: https://www.ichaus.biz/upload/pdf/Appl3_a3es.pdf ). The device iC-HG has six 500mA driver channels integrated and that maybe the reason for the higher price. There single channel integrated driver iC also. You may take a look at this table showing the different parameters: https://www.ichaus.biz/selector_laserdrivers .

Enjoy yur design work!

HTA said:

It depends on the requirements to pick the best solution. Discrete driver are cost effective but have their limitations( more details can be found here: http://www.ichaus.biz/upload/pdf/Appl3_a3es.pdf ). The device iC-HG has six 500mA driver channels integrated and that maybe the reason for the higher price. There single channel integrated driver iC also. You may take a look at this table showing the different parameters: http://www.ichaus.biz/selector_laserdrivers .

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I agree completely and getting up to 3A is a great option since most of the drivers we have are struggling to get much past 2A right now and we have laser diodes that are capable of more than 2A input now.

I do notice that most of these drivers seem to only go to 5.5v which could be a problem as some of the diodes are approaching 6v.

Overall I think the ic-haus stuff is pretty nice, but I would consider them a tool to be added to the arsenal. I also think they can be found for about $9 with some searching.


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