DIY LED driver for reef lighting

[Devs]

Originally Posted by O2Surplus

DEVS

Here's a dual CAT driver that will work. As it is, both channels are independent of each other. If you want to Parallel the channels, just connect the negative side of your LED string to both negative terminals on the board. I included pots with both chips for current adjustment. All you'd have to do is balance the load between the two CAT chips by adjusting each one to drive half your target current. For example- Say you want to drive a string of six XPG's to 1400 ma. Connect the string to one channel only, power-up, and adjust the current to 700ma. Now connect to the other channel only, power up, and adjust it for 700ma output. finally connect both channels and check the current, It should now be around your target of 1400ma.This design is nice because you're not forced to parallel drive if you don't need to, plus it has a 5V reg included for powering up the driver for situations where there is not a controller providing the 5V turn on signal or dimming signal. Feel free to mod it any way you like.

Much appreciated O2, but i've since been reading up on the LM3409, so I think I'm gonna be going with that.

Cheers

John

[sjnovakovich]

Holy Crap! I read some stuff that's over my head before, but this sent me straight to the bottom of the Marianas Trench!

[shirley386]

Question to Terahz (or anyone else that would happen to know):

If I have multiple I2C boards and want to dim them together (all at the same time); can I set the addresses the same on the I2C bus? Will they all recognize the coding from the Arduino and perform as if they were on a unique address or will there be a conflict?

[Porgy Bait]

Anybody know if any company has the Cat1401 chips in stock? Most say that they won't have any until Sept.

[Landsailor]

Octopart shows nothing, so you're probably stuck. Just go with a LM3409 design.

[Porgy Bait]

No you're right I'm stuck. I just received my Cat1401 triple boards yesterday from Itead.

[Landsailor]

Now, imagine that your business depended on those chips.

Send me the exact part number and I will check with some of our other sources. How many do you need?

[shirley386]

The correct part is CAT4101. Try here:

http://www.newark.com/jsp/search/pro...-OP&CMP=AFC-OP

[Porgy Bait]

Thanks Shirley just ordered them from Newark! Also thank you Landsailor. While I'm handing out thanks also Thank you DWZM, TheFishman65, terahz, and every body else that has a hand in this and all the many other DIY projects here at Reef Central. I've been a long time lurker here and over the years my interests have ebb and flowed in this hobby but I always know this is the place to go when I need help or good information.

[O2Surplus]

Originally Posted by shirley386

The correct part is CAT4101. Try here:

http://www.newark.com/jsp/search/pro...-OP&CMP=AFC-OP

Cool! It's nice to see that somebodies got them in stock. They've been sold out everywhere that I've looked. I lucked out though- a friend of mine, that wanted some drivers built, found some in France, and convinced the supplier to send them to me in the USA. I got 38 Cats for $76

[Landsailor]

That doesn't surprise me. I buy reels of contacts from an authorized dealer in France for about 60% less than I can buy them in the US.

The stupid part is that they are made in the USA! How on earth, they can be manufactured here, shipped to and from Europe, and still cost 40% of where we used to buy them is beyond my comprehension.

[rrasco]

One word, Capitalism.

[jc286006]

if a 48v-150 watt-3.2amp power supply is used to supply the lm3409hv drivers and the leds have Vf of 3.4 each driver can run around 12-14 leds is this correct dont have a calculater handy right now? and if i run them at 750ma this power supply should be able to supply the volts and amps for up to 4 of the lm3409hv drivers is this correct?
i am a little confused about the whole volts milliamps watts amps thing i just want to make sure my thinking is correct
james

[terahz]

Originally Posted by shirley386

Question to Terahz (or anyone else that would happen to know):

If I have multiple I2C boards and want to dim them together (all at the same time); can I set the addresses the same on the I2C bus? Will they all recognize the coding from the Arduino and perform as if they were on a unique address or will there be a conflict?

It might work. I haven't tried it though, and from what I read it depends on the i2c client (the DAC in this case).

Originally Posted by Porgy Bait

Anybody know if any company has the Cat1401 chips in stock? Most say that they won't have any until Sept.

http://www.findchips.com/avail?part=CAT4101

Originally Posted by Landsailor

The stupid part is that they are made in the USA!

Even though OnSemi has factories in the US, I'd be really surprised if the CATs are indeed made in the USA.

Originally Posted by jc286006

if a 48v-150 watt-3.2amp power supply is used to supply the lm3409hv drivers and the leds have Vf of 3.4 each driver can run around 12-14 leds is this correct dont have a calculater handy right now? and if i run them at 750ma this power supply should be able to supply the volts and amps for up to 4 of the lm3409hv drivers is this correct?
i am a little confused about the whole volts milliamps watts amps thing i just want to make sure my thinking is correct
james

3.4V * 12-14 LEDs = 40.8V-47.6V, the 14 count is pushing it.

4 strings at 750ma will be 3A. I strongly advise against using a 3.2A PSU under a constant load of 3A. My personal limit would be about 2.5A. In other words, I wouldn't put more than 3 strings on it.

To sum it up, I would put at most 3 strings of at most 13 LEDs (with 3.4Vf) on this power supply (assuming it can actually regulate the specs you list under load)

[jc286006]

thanks terahz i didnt have a calculater handy when i posted this but you have answered my question !!!! its better to be under the max to be safe!!! but i was just trying to get my head straight about how the volts amps works in trying to figure out how many drivers and how many power supplies you needfor a build
thanks for clearing it up for me
james

[Landsailor]

Originally Posted by terahz

Even though OnSemi has factories in the US, I'd be really surprised if the CATs are indeed made in the USA.

I didn't state that they were. I was referring to the multiple reels of 4,000 contacts that I buy a few times a year.

[terahz]

Originally Posted by Landsailor

I didn't state that they were. I was referring to the multiple reels of 4,000 contacts that I buy a few times a year.

My apologies, misunderstood you.

[Porgy Bait]

Thanks terahz for the link to FindChips. Its like Google for chips. I will be using it for future projects. Man I wish they had it back when I went to school it would have made life a bit easier.

[MaLi]

Greetings,

does anyone have some extra pcb for TeraHz schematic (Arduino I2C commanded) ?
PM please.

cheers,
MaLi

[Landsailor]

A couple of spreadsheet related questions for the LM3409.

How do I pick the Output Voltage of these 10W chips when the Vf is listed as "10-12"? It would be great if I could use one of these 24VDC power supplies we have laying around the shop.

What's a desired Switching frequency?

Thanks,
Jason

[Landsailor]

Double post deleted.

[Aqua@Home]

Can anybody share me the pot controlled PWM circuit diagram for dimming the led. I wanted to use it with either CAT or LM IC's.

[O2Surplus]

Originally Posted by Aqua@Home

Can anybody share me the pot controlled PWM circuit diagram for dimming the led. I wanted to use it with either CAT or LM IC's.

Aqua@Home, use a 10k pot and 549ohm resistor with the CAT4101 and a 250kohm pot and .1mf cap with the LM3409. I've attached a couple of diagrams for you, good luck with your drivers.

[Aqua@Home]

O2Surplus, thanks for providing the circuit diagrams. But I have a small problem here. I already have the pcb done for the CAT4101_triple_separate_PWM with me. I have 10pcb's with me for the CAT4101_triple_separate_PWM.

Hence I think, I would not be able to apply the design you have provided for the cat IC. I could solder the pot wires to the resistor track. But it would be too risky to do in the smd track!!!

Is there any other circuit diagram, which I could use? I tried using the 555 pwm circuit but no success

[rrasco]

Originally Posted by Aqua@Home

O2Surplus, thanks for providing the circuit diagrams. But I have a small problem here. I already have the pcb done for the CAT4101_triple_separate_PWM with me. I have 10pcb's with me for the CAT4101_triple_separate_PWM.

Hence I think, I would not be able to apply the design you have provided for the cat IC. I could solder the pot wires to the resistor track. But it would be too risky to do in the smd track!!!

Is there any other circuit diagram, which I could use? I tried using the 555 pwm circuit but no success

I built a circuit I found online, but it didn't work very well. Any reason you don't want to use something like an Arduino? That makes it a lot funner and adds a ton of capability. I wanted the pot controlled generator for a temp setup, everything is now run off an Arduino and I couldn't be happier.

This is the circuit I used: http://pcbheaven.com/circuitpages/LED_PWM_Dimmer/

http://www.youtube.com/watch?v=YnLa-hY74q4