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Can someone help me understand driver specifications?

cosmonaut

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Mar 26, 2019
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I've been looking through the commercial driver route (as opposed to the DIY approach) but I think I'm a little lost. Honestly, I'm a physics major so electronics should make sense to me but I've never had to focus on powering laser diodes. Basically, I was thinking of doing a custom build with a Osram PLT5510, but ultimately decided against that due to them being case positive and not wanting the hassle. I'll probably end up buying from the famous DTR since he has a selection of PL520s.

Now comes the driver part: I'm more than happy using DTR's included driver but I just want to get some things straight because I'm curious. It looks like my diode has an operating voltage of above 4V with the ideal range around 6V. Therefore, I'm looking for a boost driver to power it off of less than that. Most boost drivers however will have a range of values. They will say something like "Vin: 3-6V Vout 3-6V," so how do I know I will be getting a voltage out that is above the forward voltage of my diode? Similarly, since these drivers offer constant current output, the more current drawn the lower the voltage due to Ohm's law, correct?

If we look at the graph on the data sheet for the diode in question, a reasonable value for driving this is 50mA. The specs however say that the threshold current is 60mA. If I were to drive this on say an 18650, would I need a driver that can boost to at least over 6V to meet the operating parameters? Could the driver even supply 6V at all when the diode is driven with >60mA?

Finally, some help sourcing. Does DTR's driver that is included in the module fit inside the area a 17mm pill would? Are there any decent drivers being made by LPF members right now that could work for what I want?

Sorry about the newb question but thank you for your help!
 



paul1598419

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Sep 20, 2013
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You do seem confused about this. Forget Ohm's law when looking at boost drivers for these diodes. Most boost drivers will give you enough current at the forward voltage of your diode as long as it is set to the current you wish to drive it at. The reason for using a boost driver is to allow you to use one Li-ion battery. You could actually use a buck driver instead if you are willing to use two batteries. I did this with my NDG7475 build. It is easier on the batteries when you do this with high power diodes. Since you are using a low power diode a boost driver should be fine.

If you are using a boost driver here for a low power diode the driver can be attached to the diode's pins directly instead of separating it for heat sinking. So, you needn't worry about the pill size.
 




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