Re: Lava Micro FlexDrive Driver (lavadrive2) fits
TheMonk said:
IgorT thanks a lot for clear things up. [smiley=tekst-toppie.gif]
I have >300mW 635nm 9mm case positive LD that requires over 900mA to drive.
I did ask my supplier if the 3x AMC7135 board was OK to use, but they said it wasn't a good driver for this LD and I didnn't want to risk a >$300 LD. :-/
I understand your concern.. Altho i don't understand, why your supplier would think, that an AMC is not a good driver (unless of course they tested them ;D). Because from the datasheet, it seems like a very good driver.
But i made several reds using the AMC, and the first thing i noticed was of course the current changing a little with the input voltage.. But i limited it so, that the max current was bellow what i considered safe. The other thing was, that the original polarity protection makes it not work with output caps. This almost drove me nuts, as i tested 30 AMC chips, and i found two, that worked with an output cap. After changing the polarity protection (in a way, that a diode shorts the battery, if polarity is reversed), the problems with the AMCs stopped, and they are now actually quite decent for powering reds, if you can figure out a way to insulate the diode from the heatsink electrically, but at the same time not thermally (this was the hardest part)..
I also made two high current 3xAMC drivers for LikeItBright, who wanted to power a 300 and a 400mW 635nm diode, which are case positive, of course. High power diodes, like pumps and similar are case positive, so that the hot side of the die is facing the pedestal, instead of the heat having to flow through the die first, to dissipate into the pedestal, thereby cooking itself....
But with all the problems i had with the AMCs, i became hesitant to send him those drivers. I wouldn't want to be responsible for killing his >$400 diode(s)..
But now, that i figured them out, i believe they could do just fine. Of course i would test them first under hard conditions, to make sure there can be no failure... The small voltage dependant current changes are nothing for a diode that takes close to 1A.
I would use AMCs for myself, if making such a laser, and had no other choice.. But on the other hand, i do have an extremelly good common anode driver from a CNI pen, with only 0.39V dropout voltage, and the DX200 drivers are actually not bad either, altho their dropout voltage is higher (and varies). Of the three i tested, one did perfect constant current from a Li-Ion (but i killed it somehow
) another had slight changes in the current with the input voltage dropping (first down a little and then back up to where it was set), and the third was perfectly stable and actually regulated from <3V (for IR pumps with 1.8V Vf of course - 635nm diodes have a Vf of around 2.4-2.5V). But with a 3.6V Li-Ion, all three could drive a case positive 635nm diode quite reliably... But so could a properly modified and tested AMC driver....
BTW, since you want to make a high power 635nm pointer, did you buy a diode with FAC? I sure hope you did, cos i don't know how else you're going to collimate the multimode beam. A FAC microlens has to be installed in the factory, and this costs around $110 extra.
