Laser driver adjustable current

[midias]

So I have been thinking of making my own laser driver. This would be my first so I thought I would share what seems to be a very simple solution I came up with on my lunch hour. I will probably research more after work but for an hour of effort I am happy.

http://www.onsemi.com/pub_link/Collateral/CAT4139-D.PDF

 

[Ramsey_innovations]

This looks like a cool little chip but it seems like the the max current you will be able to draw is about 300ma according to the data sheet you posted: Table 5. RESISTOR R1 AND LED CURRENT
LED Current (mA), R1 ()
20.......................15
25.......................12
30.......................10
100......................3
300......................1

I suppose if thats all you need, but I wouldn't count on it pushing 300ma very long without getting hot.

Good luck to you though, making drivers can be fun and rewarding!

 

[midias]

Yea I saw the chip only wanted 350ma max so I decided to have it switch a pfet on the inductor instead of the inductor directly that way the limiting factor should be the pfet not the chip.

 

[midias]

Let me know if you guys see any other glaring errors or any questions. If I end up making them I will probably have some extras and ask for some people to help me test prototypes.

 

[Bluefan]

I'd be a bit cautios with sensitive laser diode and switching powersupplies. I'd say test the driver with a dummy load and not only check the set current but also the noise/peaks and power cycle transients.

 

[midias]

I'd be a bit cautios with sensitive laser diode and switching powersupplies. I'd say test the driver with a dummy load and not only check the set current but also the noise/peaks and power cycle transients.

All part of the plan output capacitance would be adjusted to keep peaks and noise down using a dummy load as a test. I know buck/boost style drivers have been done before and I really like the idea of powering everything off a single 3.7V battery.