DIY LED driver for reef lighting

you can run 12 off each cat4101 if it's similiar to the meanwells... just run a series - parallel config 2 strings of 6 paralleled together.. it splits the current in half thou..
 
imagex said:
you can run 12 off each cat4101 if it's similiar to the meanwells... just run a series - parallel config 2 strings of 6 paralleled together.. it splits the current in half thou..
Click to expand...
Make sure you understand the issues about running parallel strings if you do this.
 
No real reason, the CAT4101 chip isn't that expensive. Each driver board has 3 chips for a total of 18 LED's per board. My setup will have 72 LED's (90g) which means I only need 4 boards and 2 of the $15 6.5 amp power supplies. Wow, I just realized the 216 watt fixture will draw 3 more amps than my 500 watt metal halide fixture.

I wonder if people with large setups are taking that into account with their breakers. Shouldn't have to worry about any starting amps huh?
 
72 LEDs is 12 strings of . Say an Amp each. At 21 volts. So 12 amp at 21 volts. Or with 80% efficiency or 2.625 amps at 120 volts or 315 watts.

Just because you have a 6.5 amp power supply does not mean it is drawing 6.5 amps on the 120 volts. It will drawer closet to 1/5 since 5 * 24 = 120.
 
Ah, good to know. I'm not real familiar with the current relation between AC/DC. So when converting AC to DC the current is a fraction of the AC current like the DC voltage is to the AC voltage. I was under the impression that current was current even if the voltage was dropped. *off to do some reading*
 
Watts is Watts. So you use voltage * current. However hte conversion is not perfect since it takes some energy to change to waveform from AC t DC.
 
xfifi; Heat sinks.. Those parts on those boards do not lend themselves well to heat sinking. What they DO work well with is air flow, because they have so many flying leads. This makes each little lead a cooling fin. The best cooling solution in this case is a fan. Would've been nice to make those board mounting holes spaced to mount a fan. :)
 
Probably another question for kcress, but if any one knows.

The CAT4101 states that they can be run in parallel to supply more than 1 amp. They don't go much beyond that. Do they both need to be configured to supply .75 amps. Or does 1 and .5 work. Surprise I don't want to run the XP-Gs at 1.5 amps.

I am thinking moon lights. What if we configured one CAT4101 to tun at the usuall 500-750 ma and a second to run (I am guessing here) 10-100 ma. You could then run it at the high setting during the day and the low setting at night.

I am about to redo my 8 driver board. I am thinking of adding 4 PWM signal rather than 2. This might be a reason to go with 3, 1, 3, and 1 rather than 2, 2, 2, and 2.
 
Well I finally got an answer from On-Semi (took three tries for me to word the question properly). So to sort of quote them (unneeded info removed):
Response From ON Semiconductor Service Request #134984
ON Semiconductor Technical Support Center

Thank you for contacting ON Semiconductor

Please see below :
1. What are the limits of running the CAT4101 in parallel?
Yes, two CAT4101 can be used in parallel to drive a single LED.

2. Can I enable/PWM one for brightness A (which I want PWM control on) and one for brightness B (also desire PWM control ), and then enable both for a really bright level?
Yes, you can have one PWM1 signal connected to the EN of one CAT4101 and another PWM2 signal connected to the other CAT4101 EN.

Regards,
Jane

ON Semiconductor
Technical Support Center
Click to expand...
So based on this I am modifying my board. It will have 4 PWM inputs, the grounds I currently used will be replaced with 2 new PWM signals. I will then add 2 LBJs (little blue jumper) on a three pin header. So I can configure each side as
- 1 one PWM A and 3 one PWM B
or
- 2 one PWM A and 2 one PWM B
Then the same options for PWM C and D. It means the PWM don't have a separate connection for ground, but the board already has 3 ground connections.

What do folks think?
 
Well I get my LED's and heatsink in today for my 29g biocube, finally get to try my hand at an LED setup. Going to be running 12 XR-E CW and 12 XR-E RB to start with 60 degree lenses about 8" above the tank.

Also running 2 cat4101 boards with 2 drivers each off a potrans 24v 6.5a PS. Planning on running them with my hydra and tapping 5v off of it for the drivers.

Anyone measured the VCC current on the CAT4101 chips? Not finding anything in the datasheet on that. I'm sure it's pretty small, but I'm just curious. I take it several people are tapping 5v from an arduino or similar?
 
stugray said:
DWZM,

I saw this device in a recent copy of Electronics products:

http://www.micrel.com/page.do?page=/product-info/products/mic3203.jsp

A search of the DIY forum didnt turn up MIC3203 and I dont recall what all chips you messed with.
However this one looks like it has all (or most of) the requirements that I said I would like to see in a driver chip.

Stu
Click to expand...

Indeed that looks interesting. The chip itself is pretty cheap, too. I think it would be a good replacement for the NCP306x chips we started talking about at the beginning of the thread. I still like the dirt simple CAT4101 design but for someone who doesn't, that's a good chip.

DustinB said:
Anyone measured the VCC current on the CAT4101 chips? Not finding anything in the datasheet on that. I'm sure it's pretty small, but I'm just curious. I take it several people are tapping 5v from an arduino or similar?
Click to expand...

I have not measured but I've run a big huge stack of the CAT4101's Vcc pins off a single Arduino and didn't notice a thing. I know several others have as well. I'm guessing it's very very small current.
 
TheFishMan65 said:
Probably another question for kcress, but if any one knows.

The CAT4101 states that they can be run in parallel to supply more than 1 amp. They don't go much beyond that. Do they both need to be configured to supply .75 amps. Or does 1 and .5 work. Surprise I don't want to run the XP-Gs at 1.5 amps.

I am thinking moon lights. What if we configured one CAT4101 to tun at the usuall 500-750 ma and a second to run (I am guessing here) 10-100 ma. You could then run it at the high setting during the day and the low setting at night.

I am about to redo my 8 driver board. I am thinking of adding 4 PWM signal rather than 2. This might be a reason to go with 3, 1, 3, and 1 rather than 2, 2, 2, and 2.
Click to expand...

I'm pretty confident it'd be fine. You could always use some diodes to prevent any back-emf on the second (lower rated) CAT4101 though, couldn't you? My guess is that their statement of being able to run in parallel means there already is such a diode (or equivalent) internally...

[aside]
I'm about to test this in a big way, with 30 '4101's ganged in parallel, to see if they'll do a good-enough job controlling the current used in a reverse-pulse plating machine so I can do plated-through holes at home without sending off to a board-house. That's 30 connected in each direction (60 in total, but only 30 will be active at once). Combined with some high-frequency solid-state relays and an AVR, I think they'll make a good enough job. When you consider that even the lowest-priced pulse-plating PSU I can find is ~$1500, it ought to save me some cash if it works - worth a try at any rate :)
[/aside - returning to fish-related topics now ]

Simon
 
TheFishMan65 said:
72 LEDs is 12 strings of . Say an Amp each. At 21 volts. So 12 amp at 21 volts. Or with 80% efficiency or 2.625 amps at 120 volts or 315 watts.

Just because you have a 6.5 amp power supply does not mean it is drawing 6.5 amps on the 120 volts. It will drawer closet to 1/5 since 5 * 24 = 120.
Click to expand...

If it's any surprise you lost me here somehow. Where does the 2.625 come from here? Trying to figure out what type of amps I will be drawing for my build now because I am looking at two 15v 23amp supply and am nervous about the draw on my breaker as well.
 
Well that should read 12 string of 6. So now 12 string at 1 amp and I am guessing a voltage of about 21. So the power used is 12 * 21 or 252 watts. No if we only use 80% of the poer supply we need one rated at 252 / ,80 = 315 watt power supply. Put the power supply has an input of 120 volts so 315 / 120 is 2.625 amps drawn from the wall socket.

So 23 amps time 15 volts is 345 watts. I assume this is the rating so you will only use 80% of it so we don't need to divide by .80, So 345 watts at 20 volts will draw 2.875 amps from the wall.

Does that help?
 
on steveleds version of this cat4101 driver... he has a 5v chip hooked to a outlet to run a pot and it makes it dimmable is this capable on the triple board?? just add a pot on the 5v in??
 
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