DIY LED driver for reef lighting

[der_wille_zur_macht]

Haven't used one in the flesh, but I did play with TI's design tools for it back when I was working on the original NCP design I started this thread for. At that time I did not use the LM3404 because it was in an SMT package and didn't offer any benefits (based on my criteria) over the NCP. The higher input voltage sounds nice but in practical applications it's not a huge benefit to the average DIY'er (again, IMHO) because if you figure cost per watt, the typical POTRANS 24v 6.5A supply is much cheaper than any higher voltage DC supply, so the cost savings you get by having fewer drivers is negated by requiring more expensive power supplies. Though arguably an LED array with longer strings and fewer drivers will always be slightly more efficient than one with shorter strings, so you could argue that the longterm cost advantage falls in the favor of the LM.

Also, regarding efficiency, it strikes me that switchers really only have an advantage when Vin and Vout are far apart. Since we can carefully choose and control those parameters, we should be able to get efficiency with the CAT4101 that's close to or the same as what you'd get from most switchers under the same conditions.

Again though, these are all IMHO and according to my own criteria. I'd love it if someone WOULD play with that chip and report back!

 

[theatrus]

Since I'm a tinkerer, I present you with my dual LM3404HV driver board:

I haven't built it yet, still triple checking all of my work... I'll release the design under Creative Commons once I've validated that it actually does what I claim

The board has been shrunkified by careful rearranging of parts. Currently sits at 2.5inx2in. Connectors on the right are Tyco Buchannan pluggable terminal blocks, or any other 3.5mm terminal block.

Here is a feature breakdown:

= Dual LM3404HV
- 75V input
- 6 LED chains at 24V, 12 LED chains at 48V, 18 LED chains at 60V
- No need to match input voltage with output array for efficiency (it is a buck converter after all)
- up to 1A drive (1.5A overcurrent trip)
= On board ATMega88(48/168/328) TQFP
- Controls PWM channels on both drivers
- Controls Ron shutdown FET (for really-off mode)
- Connected to a half-duplex RS485 bus with RJ12 connectors (remote control - I use an RS485 MODBUS chain to talk to various gadgets in my system)
= LM5009 buck converter for local power, or MCP1702 for provided bus power (coming from the RJ12 cable in my system is +5V)
= External breakout of PWM and ON/OFF lines (no need for the microcontroller at all!)
- 2pin 0.1 header connected to ATmega ADC for "pot dimming" or (with adaptation) 0-10V control.
- 2pin 0.1 header for GND and 3.3V (pot dimming, etc)

Cost: Not fantastic. I'm not one to make the cheapest possible things...

 

[sanamyan]

Since I'm a tinkerer, I present you with my dual LM3404HV driver board:

Looks like very promising chip. Could you post schematic of your board here?

 

[der_wille_zur_macht]

Nice work! Now this thread officially covers the entire range of HP LED drivers. From my meager and dirt simple design to your powerful uc controlled design! Can't wait to hear how it works.

 

[theatrus]

Looks like very promising chip. Could you post schematic of your board here?

Will do. I'm going to do some post-vacation cleanup of the schematic and board and post the files.

 

[theatrus]

Inductor fit test (with Coilcraft samples):

 

[rascole]

Does someone have a simplified diagram of how to wire up a series/parallel system? Say 5 rows of 5 (25).

 

[TheFishMan65]

Well how about 4x5. I posted this earlier in the main LED thread, I think.

 

[rascole]

A little more simple maybe? Can fuses be put in front of each of the 4 strings to protect them if a string goes bad?

 

[TheFishMan65]

Yes, but not in the picture above. Also if one string opens the extra current will blow the other 3 string so no lights.

 

[der_wille_zur_macht]

Inductor fit test (with Coilcraft samples):

Ohh, pretty.

The third coil is for the "local power" reg to run the AVR I take it?

 

[rascole]

Fuses

Fuses

But wouldn't it be better to replace one bad LED and some cheap fuses than replace all the LEDs? At least a parellel setup can use fewer power supplies.

Yes, but not in the picture above. Also if one string opens the extra current will blow the other 3 string so no lights.

 

[der_wille_zur_macht]

rascole, I have no objection to your line of discussion, but it might be better served in it's own thread or the "big" dig LED thread - this thread is generally for discussion of DIY drivers.

 

[rascole]

You got it.

 

[theatrus]

Ohh, pretty.

The third coil is for the "local power" reg to run the AVR I take it?

Yeah, for the LM5009 buck converter. Its optional in the latest design since the logic can run off of the 5V supply over the serial bus wiring.

Fully loaded at low-qty DigiKey/Avnet/Mouser pricing I'm looking at $25 for the whole thing (minus PCB, wire, sweat, shipping). If run at 48V (12 in series, 2 sets) thats $1.04 per LED on drivers with two controllable channels.

Its not earth shatteringly cheap, but thats the price of fun :hmm5:

 

[der_wille_zur_macht]

We'll give you a 5% discount on sweat. :lol:

That's actually relatively cheap. I can't think of any constructive criticism other than that you're relying on a slightly more expensive DC power source and long LED strings, which would be fine on a large tank but potentially give less "resolution" on a smaller tank, if that makes sense.

 

[pazhope]

Hi,

Just order all the parts for 10 of the CAT4101 triple drivers, hope I don't screw up with my soldering skills

Until now I have been running with some DIY transistor drivers, but I am going for a bigger fixture so I need something a little more pro.

Well my question is:

Mouser just ran out of the VJ1206Y104KXAMC capacitor and I was thinking on switching it for the VJ1206Y104KXAMP. They are the same family and the specs look the same so I think it will work, but wanted to ask first to see if I was missing something.

Also I can't find the JP1 and JP2 headers on mouser webpage, does someone has the part number or a place to get them?

thanks in advance

 

[TheFishMan65]

I just checked mouser for 30 CAT4101 is $3.07 future electronics is $1.54. This is probably the most expensive part you are buying so you may want to try and check total price there.

For the caps I think they are the same part. The difference is the size of the reel. Were you planning on auto placing these with a machine - it might make a difference if the machine won't take a certain size reel

I used a different board so can't help on the header off the top of my head. I will see what I can find out.

 

[TheFishMan65]

OK, I found a reference back on page 14 to 3.5 mm terminals. Anything with that spacing will probably work. The companies pretty much make them interchangeable so that they can get you to switch. If you post a link to what DWZM specified (since I can't seem to find it) I can help you find an alternate. Or I am sure DWZM will be along shortly.

 

[pazhope]

Thanks! I am planning on solder them by hand so if the difference is the real it wont make any difference.

About the CAT4101 great find, since I am putting together 10 of there is a saving of 60 bucks, the problem is I already order them from mouser, so I will try to cancel my order or something.

The header parts are:
6-position, 3.5mm pitch header for output
4-position, 3.5mm header for input

I was already thinking on going to a local electric shop, they headers seem more ore less like the ones I use for my controller so I am not that worry but it may help if I can order them,