Laser driver adjustable current

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

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!

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.

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.

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.

Bluefan said:

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.

Click to expand...

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.