High Power LED Driver Circuit Help..

[cobra1]

Hi Guys

I am working on a project that requires 9 high power leds (10watt)

6 LED'S are red, and require 10v nominal input with 1000ma - 1500ma current
3 LED'S are blue and require 10.5 - 11v nominal input with 1000ma - 1500ma current

I would like to build a fairly efficient driver to power all 9 of these leds if possible.
I would also like the ability to have 2 modes of lighting.

1: Constant light,
2: Pulsing light, this would be pretty slow so it would slowly dim and then slowly get brighter.

1: Is easy, 2: im guessing i would need some sort of PWM circuit built to perform the function.


Can anyone help with pointing me in the right direction of a circuit that could do what i require??
Im thinking it might be a PWM circit with the leds on the output, that way i can vary the brightness and have the pulsing effect i want.

any help would be greatly appreciated.

 

[cobra1]

im guessing this might not be doable then???

 

[bychon]

It's doable, but right now, I have short time, and it's not a simple circuit. Yes, part one can be done with a switch. "Click", it's on. "Click", it's off. Part 2 would work with a PWM and a slow ramp to modulate the PWM. You will probably end up driving both modes with the PWM circuit because it is simple to jam a PWM in the "on" position. Oops...having a senior moment. Must look up 556 chip to see how to make a 2 sided ramp. What about sending the ramp to a voltage regulator chip and work it like a variable analog power supply instead of a PWM? That seems like it would work.

Gotta go...dentist awaits.

 

[cobra1]

cheers for the info bychon, seems like a good starting point, i will have a look into the 556 and see what i come up with.

good luck at the dentist...lol

 

[Hero999]

It shouldn't be too hard.

What's the supply voltage?

 

[cobra1]

supply voltage will be 12v, but i can also do 24v

 

[Hero999]

Here's a link to a site which discusses different LED drivers. They're all step down regulators which means the output voltage is always less than the input so you need as high as voltage as possible.

2-transistor Black Regulator

 

[cobra1]

hi guys,
i have decided to use this circuit as my ramping circuit.

https://www.electro-tech-online.com/custompdfs/2010/05/RAMPINGLED2.pdf

Hero999. thanks for the link you posted above. In your write up it says it can supply only 1 or 2 high power leds. could this circuit be modified to power 3 leds rated @ 1500ma / 10.5v each??

 

[Hero999]

Just a few of things:

Why not use a 556 rather than two ICs?

You need to use a MOSFET with a higher current rating, the 2N7000 can only handle 200mA.

It's not very efficient but will work.

 

[Integrate]

If you are still interested, I had success with something like this:
Specs & Function
You can have pwm by disconnecting the wire from V+ to the 100K resistor and connecting that to your microcontroller.

 

[cobra1]

Just a few of things:

Why not use a 556 rather than two ICs?

You need to use a MOSFET with a higher current rating, the 2N7000 can only handle 200mA.

It's not very efficient but will work.

I will be using a 556 instead, if i use a mosfet rated at 1-2amps will i be able to run 3 leds??

how ineficient would this circuit be?? and how could it be made more efficient??

 

[keny]

Driving Hi current LEDs

I was just reading about a Buck Converter IC called the HV9910B

basically for driving a hi current LED.

I just bought "Power supplies for LED Driving" by Steve Winder, let's hope I get my Sixty bucks worth...

The inductor he uses in the book is 470µH, driven by a VN3205N8 There is a pretty good schematic very similar to the one in the PDF link with values.

 

[bryan]

6 LED'S are red, and require 10v nominal input with 1000ma - 1500ma current
3 LED'S are blue and require 10.5 - 11v nominal input with 1000ma - 1500ma current

.

Is this for hydroponics lighting. Interesting to see how it turns out.

 

[muntazir mehdi]

nice
u may get help from the site
Electronic Circuits on Discovercircuits.com - Free Electronic Circuits

 

[cobra1]

Is this for hydroponics lighting. Interesting to see how it turns out.

you coul say that bryan, its for algae culture

 

[bryan]

Macroalgae for a reef tank?. A vendor I have used in the past is Sure electronics on Ebay. they sell high power drivers. Not sure of the quality, but everything I have bought from them has been good quality in the past. They usually supply a schematic so you could probably buy a coupleand make the rest up.

**broken link removed**

 

[Ubergeek63]

I was just reading about a Buck Converter IC called the HV9910B

basically for driving a hi current LED.

I just bought "Power supplies for LED Driving" by Steve Winder, let's hope I get my Sixty bucks worth...

The inductor he uses in the book is 470µH, driven by a VN3205N8 There is a pretty good schematic very similar to the one in the PDF link with values.

ouch... i really hate it when these opportunistic jerks regurgitate data sheet app notes in various forms and make a killing off of poor saps.

the supertex hv9910 is a very robust and flexible chip easily supplying what ever power level that you need to LEDs off the regulated mains... and a 555 "PWM" circuit is more likely to blow out expensive LEDs than a simple resistive heater as a series current limiter would. LEDs need to be CURRENT SOURCED, if you try to regulate the voltage you are going to damage your LEDs

 

[cobra1]

i think i may have found a circuit ideal for the job.

Google Image Result for https://gifpdf.ic-on-line.cn/0185/yb1682_440151800001.gif

would anyone know what i would have to do to change the output to 20v@2a??

 

[keny]

I would agree that the book costed too much, but then again I feel there is a certain value to having something printed in your hand than trying to scroll through a pdf file. I had the Microchip 18f4550 datasheet printed out and it's been well worth the 45 dollar trip to staples for the print job...

I'm also really eager to get my LED chops up so I felt need to participate here.

What I did notice that was pretty cool was the CPC1001N in the optek's datasheet used as isolation from the PWM source.

 

[cobra1]

the schematic in the pdf you posted would work if i knew how to change its output values.
900ma i suppose would be close enough to the 1000ma that i require, but it is not clear on what the output voltage is, i require 20v output.

also i just need to clarify something as i havnt done this before.
i understand that when a circuit is fed a certain voltage i.e 12v. the circuit will only draw the current it needs to operate.

does this work the other way round, i.e 1000ma constant, will the circuit (leds in this case) only draw the voltage they need??

the leds i plan to use are 10v when all the buck converters available are 12v, so it just got me thinking