Diode voltage?

[Anthony P]

I am designing adjustable current power supply for RGB module.

http://optoengine.com/images/Documents/OEMLasers/PL530.pdf?fbclid=IwAR3MzLQXRSVLxpFo9Kb4TPuf6nGXGqHkLszr2OnNiLHL3mPplbaPay4ogUo

It uses 3 diodes: red HL63603TG, blue PL459B, and green PL530. All have different power requirements. I intend to power them all from a single wall adapter. Each will have its own LM317 current regulator with in line current meters.

My question is about voltage. I have searched LPF and found much info on current, but little on voltage. Should I build a multi-rail power supply with 3 separate voltage regulators? red 2.7-3.0v, blue 5.3-6.5v, and green 2.2v (plus a heater voltage reg).

This project is still in the design stage. I haven't even done a breadboard yet, so nothing is etched in stone... open to suggestions.

 

[DashApple]

Since the currents are low , I would Just use one power supply to cover them all if your not worried about total power dissipation , When running the LM317 in CC any difference in voltage will just be lost as heat in the regulator .

 

[paul1598419]

I would also use just one supply for all your drivers. Since you are not using a direct diode green, you don't need a high voltage rail as the PL530 only needs a little over 2 volts Vf. There are some ready made drivers for RGB lasers that aren't terribly expensive. You might want to look into one of them.

 

[WizardG]

Should I build a multi-rail power supply with 3 separate voltage regulators? red 2.7-3.0v, blue 5.3-6.5v, and green 2.2v (plus a heater voltage reg).

NO! Whether you go with one power supply or three the output to your lasers must not be from a 'voltage regulated' driver circuit. Laser diodes need current regulated drivers.

 

[Anthony P]

Should I build a multi-rail power supply with 3 separate voltage regulators? red 2.7-3.0v, blue 5.3-6.5v, and green 2.2v (plus a heater voltage reg).

NO! Whether you go with one power supply or three the output to your lasers must not be from a 'voltage regulated' driver circuit. Laser diodes need current regulated drivers.

To clarify, I meant a voltage regulator in addition to mandatory current regulator. My concern was/is that the blue requires about 6v. If I run the other 2 at 6v they will be damaged... right? If I understand DashApple correctly, all could run 6v and cc regulator would just get hot. Fan and heatsink.

 

[WizardG]

"I understand DashApple correctly, all could run 6v and cc regulator would just get hot. Fan and heatsink. "

You do understand correctly. LM317 regulators configured for CC would (in theory) let you run with any input voltage up to about 36 volts with more waste heat the higher the input voltage is.

 

[Anthony P]

Thank you, gentlemen. I will start bread-boarding this week and do a review of rgb module with pics when completed.

 

[kecked]

Since your not modulating it why not grab an off the shelf rgbw led driver. Add voltage reg before it to supply the 5v. Will not work for higher Vf diodes as they need more voltage but should work for your needs. That’s just an example there are hundreds of chips to pick from and p,entry prebuilt.

 

[Anthony P]

Since your not modulating it why not grab an off the shelf rgbw led driver. Add voltage reg before it to supply the 5v. Will not work for higher Vf diodes as they need more voltage but should work for your needs. That’s just an example there are hundreds of chips to pick from and p,entry prebuilt.

View attachment 64303

I will look into that approach. The hobby for me is in the building of laser projects. Don't care too much for owning or collecting them. Thank you for the circuit diagram.

 

[kecked]

Same here. Circuits a random example. Just search rgbw led driver circuit. There are tons of chips to pick. Point is if you are not modulating you can do constant current will little fear of issue so long as your circuit is well behaved on turn on and turn off and the supply is stiff.