12W blue driver booster?

[alx]

Dear all,

Did someone use this driver in picture attached?

It is marked to be booster for blue diodes which support 3.7-4V2 input and 3A output. I am really in doubt that this driver will support 3Amps on output which is meaning at least 12w for blue diodes...

I've did some tests using a dummy driver + UIN = 4V (power bench supply)

- connecting at output a dummy driver (4 x 1N4X diodes ), output current is ~2A and output voltage across diodes around 4V.

- if I'm increasing number of dummy diodes, for 5 x 1N4X, I am getting Iout ~1,25A and for 6 x 1Nx I am getting Iout = 0.4A and Uout is decreasing somewhere around 2V...

Did someone used it successfully? If yes, what is the value of regulated current output when connected on blue diodes?

Regards,
Alx

 

[Cyparagon]

Some bench supplies do not operate well with switching loads like this. Try adding a large value (the bigger the better) cap across the drivers input. Or use an actual lithium cell and see if your results are the same.

Do you have a link to the driver?

 

[IWIRE]

I have a couple of those drivers I bought off Ebay. I could never get the output they stated. I also have some buck drives I got from Ebay and could never get the output they state either. Seems strange because I can always get the stated current from FlexDrives, Xboost/Xdrives and BlitzBuck drives. I haven't tried Cyparagon's tip. I'm going to try that. Thanks Cyparagon :beer:

 

[djQUAN]

It's not a true constant current driver. It's basically a boost DC-DC converter with constant voltage output and a current limiting resistor on the output.

I have made an analysis about it in a long block of text somewhere in this page: Laser pointers and modules

I have also modified it to run true constant current and paralleled two for my fan cooled 9mm build (see link in my sig). One can do only up to about 2.7A tops before current limits due to parts limits (mosfets and coil).

 

[alx]

Hi djQuan,

I saw your notes on provided link. Hm... not convinced ... maybe you are drawing 2.7A from power source, which is not the same with the current flowing on output circuit, through laser diode.

With 4 diodes dummy driver, at 4V2 input, is drawing ~2A from source and is taking out 1.15A through dummy driver. If Input voltage has been increased up to 4.5V, is drawing 2.2A from source and the output current is ~1.25A.

Also, from my research, output current is very unstable and is varying to much ... when Uin is positioned between 3.7V and 4V2.

So, I am asking you: did you measured current flowing through your laser diode for varying input voltage? Is current stable? If yes, could you please to post here complete values (Uin, Iin, Iout).

And another question: which 445nm diode are you using in conjuction with this driver: 9mm or 5.6mm?

Regards,
Alx

 

[djQUAN]

Sorry I wasn't clear. That was a modified version that runs on constant current. I may have remembered wrong, maximum current should have been 1.7A. output current increases as I increase input voltage since the LT1700 limits the mosfet current on the input side.
I was targeting 2.4A that's why I used two and reduced the output current on the pair. haha sorry about that. All that was running off of two fully charged panasonic 3400 cells in parallel.

At below 1.7A (IIRC I set it to 1.2A each) the current is stable at all battery voltages. But this was a modified version. Stock version's output current will vary depending on diode Vf and temperature.

 

[alx]

At below 1.7A (IIRC I set it to 1.2A each) the current is stable at all battery voltages. But this was a modified version. Stock version's output current will vary depending on diode Vf and temperature.

Hi djQuan,

Great to hear such news.

To be sure that I understood ok, on your modified version, you are powering it at:

- 2 x 18650 Panasonic cells
- you are using 2 x IIRC in parallel
- regulated output current is 1.2A on each IIRC

Question: each IIRC is drawing 2.7A from Panasonic cells and together are drawing 5.4A for an output ~2x1.2A=2.4A through laser diode!?!?

Regards,
Alx

 

[djQUAN]

I wasn't really sure how much it was drawing from the batts since I forgot to measure at the time. But it was pushing 1.2A each into the diode.

I could try to measure the current draw but I left my ammeter at work so it will have to wait.

 

[alx]

and definitely ... when output current is over 1A ... is almost like is not regulated at all ... and its value is dependent by temperature ... ballast (loading resistor) in series with laser diode is a bad option (at higher currents, dissipated power could exceed easier 2W, which will heat it more and its value will decrease, so current through circuit will increase "slowly fast" ...

and actual design will not permit output voltage across diode to move up or down (if required, depending by current)... because output voltage of IIRC it has fixed value by default ...

on my opinion, in the best scenario, it can be used only with a stable and constant input voltage and not with accumulators ... else, you are risking to have big surprises about current flowing trough diode ... far away to be, what you expect or you calculate ...