1.8 Ampere Driver (~9Vin)

[yesthisissean]

So I want to build a DDL/LM317 style current driver for a M140 laser diode, but the LM317 build only goes up to 1.5 Amperes

I want to find out how to build a 1.8A current driver that can use 9V....any help I will be thankful for

 

[sinner]

Kind of redundant since your last thread mentions you have decided to use the L200 driver.

As for the driver...
I saw that the LM317 Constant Current Driver was good for outputs up to 1.5A. This diode requires an amperage of 1.2A-1.8A, so the LM317 will be no good for this diode (I know you can set up the regulator with a heatsink, but I prefer not to :3).

If you want to run your m140 above 1A and you're preferring not to heatsink it, the driver would always overheat and either the thermal shutdown will occur or your whole laser will start blinking within seconds after turning it on..

My advice, Save yourself trouble and get the diode with a pre-installed X-Drive if you havent ordered yet, otherwise order a new buck driver..

If not, the better alternative to it would be LM1085/1084 if you can get one , use 0.7Ohm resistor and 16v 10up caps on input and output , make it like a ddl , Do heatsink it otherwise read the above once again..

 

[Things]

You won't be running any linear driver at 1.8A without heatsinking, that's for sure.

 

[yesthisissean]

I know that the L200 is a possibility, but I've also heard that you can set up the LM317 in parallel with another LM317. I could not find any more information about doing this...

As for the L200 voltage regulator, it is simply too complicated to impliment a viable circuit just to regulate the current. The regulator has too many capabilities and ends up being a waste of time.

but yeah, im currently (haha) trying to figure out that two LM317 parallel circuit right now

Kind of redundant since your last thread mentions you have decided to use the L200 driver.




If you want to run your m140 above 1A and you're preferring not to heatsink it, the driver would always overheat and either the thermal shutdown will occur or your whole laser will start blinking within seconds after turning it on..

My advice, Save yourself trouble and get the diode with a pre-installed X-Drive if you havent ordered yet, otherwise order a new buck driver..

If not, the better alternative to it would be LM1085/1084 if you can get one , use 0.7Ohm resistor and 16v 10up caps on input and output , make it like a ddl , Do heatsink it otherwise read the above once again..

 

[MarioMaster]

Check out the LM350 instead, you will still need heatsinking

 

[yesthisissean]

Awh I really dont want to mess with a heatsink for the regulator. How small can they be?

 

[MarioMaster]

Assuming your supply voltage of 9v and a diode forward voltage of 4.25v, the regulator will be dissipating 8.55W of heat to run the diode at 1.8A.

With no heatsinking the regulator will quickly reach thermal shutdown temperature and your laser will dim/flash as the regulator protects itself from turning into a mess of burnt plastic and silicon. No heatsink is probably doable at 1W, but at 8.55W not even close

 

[SKeeZ]

anyone know if parrallel 317's would work?

 

[The Lightning Stalker]

Yes. Each should have its own series resistor.

 

[yesthisissean]

anyone know if parrallel 317's would work?

yep, here it is with the output of 2.301A

and this one dialed in at 1.755A

 

[The Lightning Stalker]

Don't forget to add a capacitor across the diode or you'll be blowing diodes.

 

[yesthisissean]

Don't forget to add a capacitor across the diode or you'll be blowing diodes.

How do I know how much capacitance I need?

 

[The Lightning Stalker]

The drivers I've seen use around 10μF per amp of output.

 

[yesthisissean]

so if they are in parallel does it make a difference?

 

[The Lightning Stalker]

No. I would round up to the nearest amp. So say you're running at 1300mA total. I would go with 20μF.