DIY LED driver for reef lighting

[perikaruppan]

i have no other option, but to use the ZXLD IC as i have already procured 15 nos in a haste!!!

I have taken the Design of DWZM and made a pcb for 48V/7A power supply to drive 6 Drivers in 1 PCB i.e., 72 LEDs!!!! using 4 PWM signals.

Now I read from the spec sheet that the adj pin @ 1.25V gives 100% output and at 0.3V give 25% output.

And the PWM from teh Ardunio comes at 0-5V into the resistor and then onto the NPN transistor (as deviced by DWZM) and into the Adj pin.

Is this alright? kindly advice. Or is it risky for dimming on the ZXLD? as if the V goes over 1.25 the output current increases!!!

 

[der_wille_zur_macht]

i have no other option, but to use the ZXLD IC as i have already procured 15 nos in a haste!!!

I have taken the Design of DWZM and made a pcb for 48V/7A power supply to drive 6 Drivers in 1 PCB i.e., 72 LEDs!!!! using 4 PWM signals.

Now I read from the spec sheet that the adj pin @ 1.25V gives 100% output and at 0.3V give 25% output.

And the PWM from teh Ardunio comes at 0-5V into the resistor and then onto the NPN transistor (as deviced by DWZM) and into the Adj pin.

Is this alright? kindly advice. Or is it risky for dimming on the ZXLD? as if the V goes over 1.25 the output current increases!!!

In the design I published a while back, the transistor provides a path from the pin to GND, so it pulls it down to zero volts. So, as the transistor switches on and off, the pin goes from floating to zero volts. Per the datasheet, if you float the pin, it sits at 1.25v. So, the end result of my design is the pin switching between 1.25v (floating) and 0v (grounded).

The resistor on the base is just to regulate current switching the transistor, it has no real impact on the signal reaching the IC.

FWIW, I pulled that concept right out of the datasheet, so if it doesn't work, it's their fault! :lol:

 

[marspeed]

Or, a simple conversion circuit to generate a PWM signal from whatever source you have. What would you have available to control the drivers?

<meta **********="CONTENT-TYPE" content="text/html; charset=utf-8"><title></title><meta name="GENERATOR" content="OpenOffice.org 3.1 (Win32)"><style type="text/css"> <!-- @page { margin: 0.79in } P { margin-bottom: 0.08in } --> </style> planning on using an ardunio for my build but
my little LED project has mushroomed beyond my tank
my son has DMD and was critically ill for the last year he has made a recovery beyond the expectations of all his doctors including more than one hundred doctors at a symposium thanks to professor John R Bach MD at UMDNJ. now that he feels much better he has big plans. Solar panels deep cycle battery's and LED's every where, for his room, wheelchair and so on at the same time my wife would like to use LED's for her tortoise and water turtles so I was curious how to dim the 4101
without an ardunio


marc

 

[shackscs]

So digikey was out of the two following items. For kicks and giggles I put in the digikey product number for the first one and voila!!! It brought back the cap that I needed. Smooth. Very Smooth

Digikey 493-1905-ND
Mouser 647-UPW1H221MPD

Unfortunately it did not work for the other one that I need:
Digikey 811-2046-ND

However a product search for 100uH 1A brought back this:

Mouser 13R104C
http://www.mouser.com/ProductDetail/Murata-Power-Solutions/13R104C/?qs=sGAEpiMZZMukHu%252bjC5l7YUaCifuFHuH%2fUqyjtq4%252bX2o%3d
Is this good enough?


Mouser

 

[marspeed]

Manufacturer Part Number13R104C at digikey

 

[shackscs]

What's the difference between the 13R104C and 811-2046-ND or does it not make a difference?

 

[marspeed]

they seem to have the same Manufacturer Part Number13R104C

 

[shackscs]

Thanks

 

[perikaruppan]

thanks dwzm. i also saw that on the spec sheet. but didnt know how the transistor will operate in 0-1.25v if there is a pwm input of 0-5v. so it is not proven then.

 

[shackscs]

Thanks, now to fill my cart with stuff to make up a decent order or I might to try to get them from the local Rat SHack.

 

[der_wille_zur_macht]

Unless your Rat Shack is a magic place different from all other Rat Shacks, it probably won't carry those parts.

 

[shackscs]

Yeah, I figured as much so I went and ordered the parts from Mouser along with an RTC, 3v battery holder and other things to make the order worth spending 4.50 for shipping.

 

[shackscs]

The mpja.com website has a 6.5A 24v supply that's only $15. You can drive three of the NCP3066 dual drivers on one of those if you keep the current below 600mA or so, with a reasonable headroom. That's 48 LEDs, three PCBs, 6 ICs, on one power supply.

DER do you have a wiring diagram for this? The PS shows only two -V and +V outputs.

I ordered 3 of these for my build but not sure I am following the wiring.

 

[der_wille_zur_macht]

The two +V output terminals are electrically the same - you can connect wires to either. Same with the -V terminals. They just provide two of each so you can spread things out if you want to. You can connect multiple wires to one screw terminal, so just stack them up however you want. You want the drivers to be parallel - i.e. connect all the Vin from the drivers to +V on the PS, and all the GNDs on the drivers to the -V on the PS.

"Progress" on the CAT4101 prototype - the board house sent me shipping notification yesterday. I looked at the EAGLE design to make sure I had all the right pieces, and I realized the three caps on the +V connection for the LED strings aren't grounded on the board. No biggie, I can just make a solder bridge to the ground plane that surrounds the parts, and I'll fix it for the next run of the boards.

 

[stephenrwright]

Got my CAT4101 prototype together, and when I adjust it for 700ma its only got 18v across the 6 PHILIPS LUMILEDS Rebel LXML-PWC1-0100, 3v each. I was expecting 3.40 (20.4v total) based on the datasheet


Am I doing somthing wrong? Anyone else using the Rebel LEDs with this driver?

Thanks
Steve

 

[der_wille_zur_macht]

Are you measuring current and voltage on the output side? How about the input side? What power supply are you running the driver on?

 

[shackscs]

Well the post office has been busy!!

I got my LEDS, PS, Soldering Iron station, Digikey and Mouser orders all on the same day. Feels like Xmas.

The only thing missing is my driver boards.

Are there any other must haves I need to add to my workstation?

 

[kcress]

A root beer soda tap.

 

[der_wille_zur_macht]

Tweezers, good wire strippers, desoldering braid, multimeter, small benchtop vise or "helping hands" tool.

And good lighting plus a magnifying glass or loupe if your vision is as bad as mine!

 

[stephenrwright]

Are you measuring current and voltage on the output side? How about the input side? What power supply are you running the driver on?

I was measuring the current on the output side, and the voltage on both the input and output. The power supply is one of these, I had it adjusted all the way down, but that still left the input about 2.5v higher than the output. So I added one more LED for a total of seven, at 3.1v each, 21.7v total and adjusted the power supply to keep the input less than 1v above the output. The 4101 sense resistance matches the datasheet, 780 ohm for 700ma I was just expecting the LEDs to drop closer to 3.4v. For the prototype I have it all mounted on a aluminum flat 1.5" wide with the LEDs spaced about 2" apart, and it gets very warm, so I am going to think some more about cooling. I was going to use two 1'x2' 3/16" aluminum plate I have, but think I am going to have to do more to dissipate the heat.