Looking for a specific DC CC driver for LEDs

[oreo57]

Yes, the jumper matrix allows selecting a range of output current, making the driver more versitile. Fire it up and find out, it works on of two ways, adding resistance increases current, or reducing resistance increases current.

The way they have it labeled and the way their smaller drivers work makes me think the latter.

As you've probably figured out their documentation isn't that good.

Pretty sure they are "additive".. i.e add jumper til total output is set..

 

[karimwassef]

As received
<a href="http://s1062.photobucket.com/user/karimwassef/media/FF5D1D4C-88C1-4439-BD9E-7051C9818A52_zpsigryq4dz.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/FF5D1D4C-88C1-4439-BD9E-7051C9818A52_zpsigryq4dz.jpg" border="0" alt=" photo FF5D1D4C-88C1-4439-BD9E-7051C9818A52_zpsigryq4dz.jpg"/></a>

Jumpers out
<a href="http://s1062.photobucket.com/user/karimwassef/media/72BF694B-0985-4CE4-921A-2985D78F233A_zpsf0ru2jxl.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/72BF694B-0985-4CE4-921A-2985D78F233A_zpsf0ru2jxl.jpg" border="0" alt=" photo 72BF694B-0985-4CE4-921A-2985D78F233A_zpsf0ru2jxl.jpg"/></a>

Jumpers in at max (I think)
<a href="http://s1062.photobucket.com/user/karimwassef/media/4502402B-ED54-47AE-8F53-271A26891518_zpsopur2ejg.jpg.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/4502402B-ED54-47AE-8F53-271A26891518_zpsopur2ejg.jpg" border="0" alt=" photo 4502402B-ED54-47AE-8F53-271A26891518_zpsopur2ejg.jpg"/></a>

 

[zachts]

I think you are correct. as shipped looks like it was configured for 300mA with the other jumpers not connecting the circuits and just stored there. Curious how the test fire goes. I guess they just sent an extra jumper?

 

[oreo57]

I think you are correct. as shipped looks like it was configured for 300mA with the other jumpers not connecting the circuits and just stored there. Curious how the test fire goes. I guess they just sent an extra jumper?

Yep the big "sum" sign is a dead give away...

Σ

 

[theatrus]

My test boards showed up sometime last week, but just got around to pulling them out of the envelope.

Inductor "for scale", which is a fair chunk beefier than the other units.

I'll report back soon.

 

[karimwassef]

Wow. Looks very professional. As slow as I go, you might end up testing yours before I get to mine...

Work is a cruel mistress, but I love her too.

 

[theatrus]

It is!

I need to double check if I ordered the sense resistor for 4A or 3.5A, might as well test at the limits

 

[oreo57]

like watching an artist paint..

 

[zachts]

Yep the big "sum" sign is a dead give away...

Σ

I knew that was there for a reason, didn't have a clue what it meant :lolspin:

 

[oreo57]

I knew that was there for a reason, didn't have a clue what it meant :lolspin:

geek speek..

 

[zachts]

geek speek..

Gonna have to study up on that dialect...

 

[theatrus]

Fresh from the toaster:

I don't have any suitably high power LEDs, so I'm making do with this:

Based on initial tests, it works well. The hottest component is the shunt - something to tweak in the future. I'm waiting for some actual LEDs (the 100W 3A Royal Blues).

Still more testing to do (UVLO, etc) but its functional. I can build another board from parts if there is interest.

 

[karimwassef]

very nice and very compact. Can you dim it with a digital signal? does it need a dedicated voltage for the IC or can it run directly off the input 36V? what's the efficiency of 36 to 33 at 3A?

 

[theatrus]

The EN pin is a dimmer signal. It's strapped to Vin with the yellow wire. You can also feed a 0-2V signal which influences the current limit - not the same range of control but no PWM.

No logic supply needed, just Vin. I haven't measured efficiency, but expecting >>85%.

 

[theatrus]

Did a basic test with a 100W royal blue LED. Some notes:

- An in->out differential voltage minimum of about 3-4V is ideal for the control scheme of the LM3409. If its way too low, it will run at peak inductor current (so +10%), if its barely too low, the constant off time variable frequency control scheme is audible (annoying), and after about 3.5V its fine.
- The Vf of these LEDs changes a good amount as they heat up. The 30V LED is really more around 34V. With the above mentioned variable switch frequency, you can hear it ramp
- Efficiency is good as the convertor is not hot (lots of science here), while the LED I can only run for about 5minutes before it burns a hole through my bench (4x4x3in fin heatsink). I'll get setup for actual measurements soon.

 

[karimwassef]

Excellent. How are you cooking the LED? Do all the chips come on at once ?

 

[theatrus]

Its a classic parallel+series Chinese $10 100W module, just an anode and cathode connection. Driven at ~3A.

 

[karimwassef]

cooking = cooling .. mistype

Some chips are better than others. If you ramp the voltage slowly, you can see if all the LEDs come on together or in groups.

 

[theatrus]

Looking for a specific DC CC driver for LEDs

Ah, I see what you mean. Mounted on a passive heat sink which is undersized, weighed down by an old hard drive on top.

I haven't checked the minimum Vf of each internal parallel segment. The tempco is a real feature though

 

[zachts]

Ah, I see what you mean. Mounted on a passive heat sink which is undersized, weighed down by an old hard drive on top.

I haven't checked the minimum Vf of each internal parallel segment. The tempco is a real feature though

yeah, the light emitting side gets darn hot on those at close range, they say LEDs are cool to the touch but not with that many photons in such a small space! and even with the current generations of "3watt" chips that is really a myth, even those could scorch paper and will melt plastic at close range under the right conditions.