High Power LD Driver

[TheMonk]

Guy I need help with driver.

The LD body is positive and need 900mA.

I can not isolate the LD body from the host.

I don't think any of the drivers we have here are usable, they all positive regulators. :-/

I think I need a negative regulator capable of 900mA? :-/


Any help is appreciated.

 

[ndrew2505]

ive got an ldd40 from merideth if you want to purchase it. im only asking what i paid for it.

http://www.mi-lasers.com/cgi-bin/sh...hstart=0&template=Templates/SearchResult.html

 

[thesk8nmidget]

what kind of diode?

 

[pocketfluff]

the negative version of lm317?

 

[kernelpanic]

monk,

I've been working on this negative regulator- http://www.laserpointerforums.com/forums/YaBB.pl?num=1220866048

The circuit on that thread is for 405nM from a 6v supply. But it could easily be tuned for a different combination. Only the resistor values need changed...

The IRL510 can easily handle 900mA. But you may need a heatsink if your supply voltage differs too much from load voltage.

cheers,
kernelpanic

 

[billg519]

Sounds like an IR diode ... Make your host a positive ground system. Then, you could use a negative side regulator. Or, you could still use a positive side regulator if you can fit it in the tailcap, or otherwise get it between the positive terminal of the battery and the body of the laser. Easier to do this if you are making your own host. As suggested above by pocketfluff, you could use the negative counterpart to the LM317, the LM337, it can handle up to 1.5A. Kernelpanic's design is also very interesting. One of these options should work for you.
DX also sells negative side current regulators, but the closest values are 700ma or 1050ma, so probably not applicable here.

 

[TheMonk]

The Diode is <300mW 635nm 9mm by PLT Technology. The host is Romisen http://www.dealextreme.com/details.dx/sku.7246. The Diode is very expensive I need a proven driver for it also the max driver size is no more than 15x26mm.

I was planning to use two Groove Drivers connected in parallel, but I can not isolate LD body for max heatsinking.

BTW anybody knows how to connect two drivers to parallel to double the current?

 

[jayrob]

The Diode is <300mW 635nm 9mm by PLT Technology. The host is Romisen http://www.dealextreme.com/details.dx/sku.7246. The Diode is very expensive I need a proven driver for it also the max driver size is no more than 15x26mm.

I was planning to use two Groove Drivers connected in parallel, but I can not isolate LD body for max heatsinking.

BTW anybody knows how to connect two drivers to parallel to double the current?

If you have room for a DDL style driver, you could just connect it up case positive couldn't you? A 1.3 ohm 1 watt resistor should put you right around 960mA's.
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=1.3W-1-ND
Jay

 

[rkcstr]

the problem with doing case positive is that the input positive and the output positive are not tied together, that's where the circuit regulation is going on, however the input/output negative are the same, which makes it simple for making a case negative solution. If you hook up a standard positive regulator to a case positive host, you have to isolate the diode case (also positive) from the host case, otherwise you're causing a short.

this is why he's looking for a negative regulator, so that its essentially opposite, regulating the negative side and having common input/output positive.

 

[jayrob]

Oh...ok. I thought that he was saying that he had a special diode that needed a positive connection to the diode case pin.
Jay

 

[rkcstr]

Anyway, it looks like the negative regulators work with the same type of circuit as the positive, so that may work: use the LM337 instead and making sure your caps (and protection diode) are in the right polarity and your "Vin" connected to the battery negative and then have your host as case positive (to the positive case pin on the LD).

Here's the PDF for the LM137/337:
http://cache.national.com/ds/LM/LM137.pdf

 

[toked323]

I found this lm317 calculator
http://www.cpemma.co.uk/317calc.html