pandimus
Active member
so just bridge pin one and two and i dont have to worry about another power supply? Just one for my typhoon?
DIY LED driver for reef lighting
- Thread starter der_wille_zur_macht
- Start date
so just bridge pin one and two and i dont have to worry about another power supply? Just one for my typhoon?
Yep! solder Pin1 & Pin2 together and connect the PWM signal/ ground wires from the Typhon. That's it.
rrasco
Active member
Built my PWM dimmer this morning. It is actually two circuits so I can dim both white and blue independently. The right circuit is being tested in the photo and video. The only minor issue right now is with this circuit the duty cycle can only be reduced to 50%. That will be solved with the arduino that will eventually replace this, but something to keep in mind.
Here is a little demonstration:
http://www.youtube.com/watch?v=YnLa-hY74q4
Here is a little demonstration:
http://www.youtube.com/watch?v=YnLa-hY74q4
der_wille_zur_macht
Team RC
Huh. Must be something in that specific circuit, because there are other 555-based designs that happily go down to zero duty cycle.
der_wille_zur_macht
Team RC
I've used a schematic similar to yours:
I can't see any obvious differences. Are you sure the pots you're using actually allow the wiper to go from one end fully to the other? i.e. that they don't have some "base resistance" on one of the ends or anything weird like that?
I can't see any obvious differences. Are you sure the pots you're using actually allow the wiper to go from one end fully to the other? i.e. that they don't have some "base resistance" on one of the ends or anything weird like that?
der_wille_zur_macht
Team RC
Given the length of this thread and the way things have changed I'm going to make an attempt to summarize the "current state" of our DIY LED efforts. We're generally using two ICs right now so I will write a bit about each.
The CAT4101 is a linear constant current LED driver. Datasheet is here:
http://www.onsemi.com/pub_link/Collateral/CAT4101-D.PDF
It is limited to 1A and 25v. The 25v limit means it maxes out at 6 - 7 typical HP LEDs. It can be controlled via PWM. The fact that it's linear means it turns extra power into heat. This is a big caveat - if you use this chip, you MUST carefully consider the voltage of your DC power supply vs. the voltage required by your LEDs. The power supply needs to be at least .5v higher than your LED string needs, but any higher than that means you're getting less efficient - and if you get more than a few volts of difference, the driver will overheat and shut down.
The circuit required is very simple, there are basically two capacitors and a resistor. The chip is surface mount but very easy to solder, and most designs make use of large SMT components so it's a good introduction to surface mount. The only real decision to make for component selection is choosing a sense resistor to get the drive current you want in your LEDs. There is a table in the datasheet that lists appropriate values.
There are a few pcb designs. TheFishMan65 has a design with 5 drivers on the same PCB, connections for a pot to dim, and some other nice features. I have a design that assumes PWM dimming and has three drivers per PCB:
http://code.google.com/p/hpled/downloads/list
Look for the CAT4101 files.
The LM3409 is the other current "favorite" chip. It has a datasheet here:
http://www.ti.com/lit/ds/symlink/lm3409.pdf
The chip has provisions for dimming by PWM or analog signal. In the HV version, it will work up to 75v, though higher voltages start to become questionably dangerous. Most people either use the "normal" version around 24 - 30v, or the HV version up to 48v or so. It is a switching controller and uses an external MosFET to control current. It's limited to 5A drive current. The high current and high voltage limits mean it can drive very large and complicated LED arrays (theoretically up to 375w, but practically most people don't go above maybe 150w). This is a great driver if you have a large LED array but it's very flexible (and not that expensive) so it is also often used for smaller or low-power arrays that need flexibility not available in other chips.
This flexibility comes at a price. The chip is much harder to solder (very fine pitch and a ground pad on the bottom that's not exposed). Also, component selection requires lots of careful planning and some pretty wild math. There's a spreadsheet here to help with component selection:
http://code.google.com/p/hpled/source/browse/trunk/lm3409/lm3409_component_worksheet.xls
Component selection basically consists of determining your expected input and output voltages and desired drive current, then determining the Roff (timing resistor) to get a reasonable frequency. Once you know frequency you can choose the inductor to get a reasonable ripple. Then you can fine tune the drive current by adjusting Rsense and tune input and output ripple by selecting the right caps. Also you need to carefully consider the current and voltage limits on the components you choose, as it's typical to bump against the limits on some of the components (particularly the diode, FET, and inductor).
terahz has the most commonly used design for this chip, it allows PWM or analog dimming. As soon as I find the most recent version I'll link it here, or maybe he will come along and do so.
At a very high level, I would choose between the two ICs like this: If you need 1A or less of drive current, and can get a DC power supply closely matched to your LEDs' Vf, and don't mind being limited to 6 or 7 per string, use the CAT4101. If any of those things aren't true, use the LM3409.
The CAT4101 is a linear constant current LED driver. Datasheet is here:
http://www.onsemi.com/pub_link/Collateral/CAT4101-D.PDF
It is limited to 1A and 25v. The 25v limit means it maxes out at 6 - 7 typical HP LEDs. It can be controlled via PWM. The fact that it's linear means it turns extra power into heat. This is a big caveat - if you use this chip, you MUST carefully consider the voltage of your DC power supply vs. the voltage required by your LEDs. The power supply needs to be at least .5v higher than your LED string needs, but any higher than that means you're getting less efficient - and if you get more than a few volts of difference, the driver will overheat and shut down.
The circuit required is very simple, there are basically two capacitors and a resistor. The chip is surface mount but very easy to solder, and most designs make use of large SMT components so it's a good introduction to surface mount. The only real decision to make for component selection is choosing a sense resistor to get the drive current you want in your LEDs. There is a table in the datasheet that lists appropriate values.
There are a few pcb designs. TheFishMan65 has a design with 5 drivers on the same PCB, connections for a pot to dim, and some other nice features. I have a design that assumes PWM dimming and has three drivers per PCB:
http://code.google.com/p/hpled/downloads/list
Look for the CAT4101 files.
The LM3409 is the other current "favorite" chip. It has a datasheet here:
http://www.ti.com/lit/ds/symlink/lm3409.pdf
The chip has provisions for dimming by PWM or analog signal. In the HV version, it will work up to 75v, though higher voltages start to become questionably dangerous. Most people either use the "normal" version around 24 - 30v, or the HV version up to 48v or so. It is a switching controller and uses an external MosFET to control current. It's limited to 5A drive current. The high current and high voltage limits mean it can drive very large and complicated LED arrays (theoretically up to 375w, but practically most people don't go above maybe 150w). This is a great driver if you have a large LED array but it's very flexible (and not that expensive) so it is also often used for smaller or low-power arrays that need flexibility not available in other chips.
This flexibility comes at a price. The chip is much harder to solder (very fine pitch and a ground pad on the bottom that's not exposed). Also, component selection requires lots of careful planning and some pretty wild math. There's a spreadsheet here to help with component selection:
http://code.google.com/p/hpled/source/browse/trunk/lm3409/lm3409_component_worksheet.xls
Component selection basically consists of determining your expected input and output voltages and desired drive current, then determining the Roff (timing resistor) to get a reasonable frequency. Once you know frequency you can choose the inductor to get a reasonable ripple. Then you can fine tune the drive current by adjusting Rsense and tune input and output ripple by selecting the right caps. Also you need to carefully consider the current and voltage limits on the components you choose, as it's typical to bump against the limits on some of the components (particularly the diode, FET, and inductor).
terahz has the most commonly used design for this chip, it allows PWM or analog dimming. As soon as I find the most recent version I'll link it here, or maybe he will come along and do so.
At a very high level, I would choose between the two ICs like this: If you need 1A or less of drive current, and can get a DC power supply closely matched to your LEDs' Vf, and don't mind being limited to 6 or 7 per string, use the CAT4101. If any of those things aren't true, use the LM3409.
Thank you DWZM!
ZenMastr1968
New member
Thanks DWZM.... I was trying to re-read the whole thread to figure out where things currently stand. Now I know 
My Hydra has been itching for something more important to do for awhile and I had been saving up for a Cree retrofit for the BC29 I setup last year....since I now have the money and nanotuners isn't an option, I'm back onboard here.
I'm looking to build a 24 led array - not sure how many strands of which color yet . Have seen some good builds along this line and am still looking for a driver to fit my needs. I want to do sunrise /sunset dimming via Hydra (pwm), but want the leds to go completely off. I think I remember reading in this thread one of the designs could do that (I was told that meanwells could only go down to a certain point and then you had to kill the mains so I gave up that route). Is that still true and if so which design?
Sent from my LG-P999 using Tapatalk
My Hydra has been itching for something more important to do for awhile and I had been saving up for a Cree retrofit for the BC29 I setup last year....since I now have the money and nanotuners isn't an option, I'm back onboard here.
I'm looking to build a 24 led array - not sure how many strands of which color yet . Have seen some good builds along this line and am still looking for a driver to fit my needs. I want to do sunrise /sunset dimming via Hydra (pwm), but want the leds to go completely off. I think I remember reading in this thread one of the designs could do that (I was told that meanwells could only go down to a certain point and then you had to kill the mains so I gave up that route). Is that still true and if so which design?
Sent from my LG-P999 using Tapatalk
der_wille_zur_macht
Team RC
Both of the chips mentioned above are capable of full shutdown via the PWM dimming input. In fact that's how I am running things on my tank. If you use terahz's LM3409 design make sure you get the latest version as earlier versions didn't shut down correctly when operating with analog dimming.
In your case it will probably come down to how many different strings you have and if their Vfs are similar. If you end up with lots of different colors at lots of different Vfs the CAT4101 is a pain because it's hard to tune a single DC supply to cover a wide range like that. So you might either have to use several DC supplies (not the end of the world) or use the LM3409 for some or all of your strings.
In your case it will probably come down to how many different strings you have and if their Vfs are similar. If you end up with lots of different colors at lots of different Vfs the CAT4101 is a pain because it's hard to tune a single DC supply to cover a wide range like that. So you might either have to use several DC supplies (not the end of the world) or use the LM3409 for some or all of your strings.
ZenMastr1968
New member
Thanks, I'll sort out my strings and/or colors and see where that "LEDs" me....:lol2:
Sent from my LG-P999 using Tapatalk
Sent from my LG-P999 using Tapatalk
Last edited:
terahz
1x10^12 Hz
Hey DWZM, nice summary. If only we had a RC wiki ...
Latest schematic, board and parts list for 1A, 48Vin for my LM3409 board can be found here:
https://github.com/TeraHz/I2C-LED-Driver
...Latest schematic, board and parts list for 1A, 48Vin for my LM3409 board can be found here:
https://github.com/TeraHz/I2C-LED-Driver
GreenHammer
New member
Any chance someone can publish the calculator spreadsheet for the LM3409 with the values needed to run Cree's XP-G at 1000ma and XP-E LED's at 700ma, with 24v and 48v power supplies? I think that since these are some of the most popular setups used today, having the values to run them will ease the use of the LM3409 based driver and also will serve as guides to calculate the working values of other LED's.
PS: If someone can also add calculations for the Cree XM-L running at 1.5~2.0 amps, I won't be offended at all!!!:lolspin:
PS: If someone can also add calculations for the Cree XM-L running at 1.5~2.0 amps, I won't be offended at all!!!:lolspin:
hi...
I have problem with this driver.
I have built a board for 48v 700mA with:
Vin = 50V
Vo = 48v
Roff = 7870 ohms
L1 = 47uH
Rsns = 0.33 ohms
the driver to whistle in the background.
if I dim with arduino pwm, 0% to 20% of the whistle is strong, if I dim to 100% decreases the whistle.
why?
I have problem with this driver.
I have built a board for 48v 700mA with:
Vin = 50V
Vo = 48v
Roff = 7870 ohms
L1 = 47uH
Rsns = 0.33 ohms
the driver to whistle in the background.
if I dim with arduino pwm, 0% to 20% of the whistle is strong, if I dim to 100% decreases the whistle.
why?
Pcb
Pcb
Hi Terahz,
Thanks for the recent update. I am ready to order my parts for this project. Getting the parts from Mouser seems pretty straight forward but I have no idea how to order the PCB'S. I clicked on the link to Seed and I didn't see how to order your design from them. I am probably missing something obvious. Can anybody help me out? I sure need to get going on this project. Thanks,
Clif
Pcb
Hi Terahz,
Thanks for the recent update. I am ready to order my parts for this project. Getting the parts from Mouser seems pretty straight forward but I have no idea how to order the PCB'S. I clicked on the link to Seed and I didn't see how to order your design from them. I am probably missing something obvious. Can anybody help me out? I sure need to get going on this project. Thanks,
Clif
What frequency are you using for the PWM?
If you are using software PWM, that is a low enough frequency you might be hearing some hystersis. Just like flourescents sometimes put out a 60hz buzz.
Not sure, but that's my guess.
== John ==
the PWM frequency of Arduino is approximately 500Hz
