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Using Arduino => Project Guidance => Topic started by: sjim on Jan 30, 2013, 02:08 am

Title: 3w RGB color bar (BOM w/ TLC5940, Fets, UNL's
Post by: sjim on Jan 30, 2013, 02:08 am
I want to make fixtures with 6 3w RGB's (3.5v blue/green and 2.5 red @350ma) and wanted
to use this preprogrammed mini 3ch RGB controller-below, some say they wouldn't go over 2amp per channel. Could this be
done and what parts (TLC5940, npn, mosfets(p/n), LM317s, constant source/sink...etc) would I need for such as small wash color bar.
 I could forego the mini controller but would need a build to support pwm.

mini RGB controller:
(http://www.ebay.com/itm/12V-12A-3-Channels-Mini-Controller-for-RGB-Strip-Light-/140818921963?pt=US_Car_Lighting&hash=item20c97639eb)

These are the RGB's (look to be common anode)
http://www.ebay.com/itm/320938690780?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649


I seen posting below, is this a viable solution to using the TLC to get 350ma per channel ?
"I used ULN2003 TransistorArrays (they are just about 70cent for 7channels) and 1W resistors to get enough current through.
The ULN2003 needs inverted signals on the base, so I used 74HC04 HexInverter to get the right HIGH and LOW signal."


-------Also---- but how do I connect a pwm device or RGB controller to this-----
Could using these below be one possible solution for the drivers?
http://www.ebay.com/itm/2pcs-3W-RGB-LED-Driver-Converter-Transformer-DC12-24V-for-3W-RGB-Light-Bulb-Lamp-/221182454255?pt=Vintage_Electronics_R2&hash=item337f8069ef

Title: Re: 3w RGB color bar build-out
Post by: johnwasser on Jan 30, 2013, 03:49 pm
The 'mini RGB controller' is common-anode, 12V, 4A per channel.

You need some way to limit the current through each LED.  You could use series resistors:

For each blue and green:
12V - 3.5V = 8.5V across the resistor.
8.5V at 350 mA = 24.3 Ohms  (call it 25)
8.5V * .35 A = 3W  so you will need resistors rated 3W or more.

For each red:
12V - 2.5V = 9.5V across the resistor.
9.5V / .350 A = 27.1 Ohms  (call it 28)
9.5V * .350 A = 3.3W  so you will need resistors rated 3.5W or more.

Six LEDs, each drawing 350 mA is 2.1A, well within the stated 4A-per-channel limit.

As an alternative to the series resistors you could use a constant-current regulator PER-LED.  The LM317 adjustable voltage regulator can be wired as a constant-current source.

If you had separate R, G and B LEDS you could put several in series and need only one resistor for each series string:

For three blue or green in series:
12V - (3*3.5V) = 1.5V across the resistor.
1.5V / 0.35 A = 4.28 Ohms  (call it 5)
1.5V * 0.35 A = 0.525W  so you will need resistors rated 1W or more.
Title: Re: 3w RGB color bar build-out
Post by: sjim on Jan 30, 2013, 08:54 pm
I'm wondering how well the LM317 can do fading..etc  I found this circuit that looks like it would work really well, although the mini 3ch RGB controller uses programmed modes with pwm and so I don't know how these two will work together, perhaps, it will work fine.  I'd like to consider using TLC5940 or Mosfet N or P, but don't know exactly what the MOD/layout would be for either (at this moment) and if could still use mini 3ch controller.

http://projects.dimension-x.net/archives/37




Title: Re: 3w RGB color bar build-out
Post by: sjim on Jan 30, 2013, 11:33 pm
I know the TLC5940 can only do 120ma per channel 16 which is 5 RGBs but I'd have to mosfet p (I believe) do regulate current before entering the TLC, does this sound right?  It would be more feasible to just do 5 RGBs(3w) per fixture and therefore only needing single TLC per fixture, however, wouldn't I need a mosfet per color so in this case 15 of them?

I suppose you must run these 4pin 3w RGB in parallel?  or could it done in series?

What need to find is several circuits used with high voltage/current LED drivers..etc
Title: Re: 3w RGB color bar (BOM w/ TLC5940, Fets, UNL's
Post by: dtokez on Jan 31, 2013, 01:45 am
http://arduino.cc/forum/index.php/topic,139792.45.html#msg1072956

check out the top post on the thread I linked above written by David (DC42), I'm using a TLC in that config and it drives LED strips nicely :)

The TLC will not source 120mA per channel with them all active, I think it can only source 120mA max between all channels, its only a small IC at the end of the day so to have almost 2A running through it would produce magic smoke. You could use big resistors to regulate the current or a driver such as http://www.diodes.com/datasheets/ZXLD1360.pdf and use the PWM signal from the TLC to control the dimming on the ADJ pin - if you read through the whole thread I linked to it will become clearer.
Title: Re: 3w RGB color bar (BOM w/ TLC5940, Fets, UNL's
Post by: sjim on Jan 31, 2013, 08:31 pm
Thankyou... I tried following the threads (gets a bit confusing for me) not great at reading circuits, moreless better at drawlings ,lol.   I'll look up the ZXLD1360 and do some learnings about it.  If I do use the TLC  it would give me multiplexing capabilities or individual control over each RGB within fixture (nice to have), but, could go either way.  Have you used the ZXLD1360  ?     
Title: Re: 3w RGB color bar (BOM w/ TLC5940, Fets, UNL's
Post by: dtokez on Jan 31, 2013, 08:57 pm
yes I'm using some ZXLD1360's in some Halogen replacement LED bulbs and the Tlc can control the brightness

check out this post (and the attached schematic) for the way to connect them up, let me know if I can clarify anything!
Title: Re: 3w RGB color bar (BOM w/ TLC5940, Fets, UNL's
Post by: sjim on Feb 01, 2013, 06:33 am
After look up the ZXLD1360, that's exactly what I need... (also HV9910 possible supposedly), would need one per 3wRGB.  Do you have a drawling of your circuit available, what parts would I need besides the 1360 and 5940, capacitors, resistors..etc  for 350ma per ch for each RGB?  Would the flow go as folllows:  12v(power) > 1360 > TLC5940 > RGB led  and/or what pieces hang off of any of these?   R1, R2, uf's...etc

Thank you, this will be such a big help!

Title: Re: 3w RGB color bar (BOM w/ TLC5940, Fets, UNL's
Post by: dtokez on Feb 01, 2013, 10:23 am
Sorry I forgot to post the link! http://arduino.cc/forum/index.php/topic,139792.msg1052456.html#msg1052456 (drawing of the circuit I used attached).

The 1360 datasheet should show an example circuit also for working out its support components.

it would be more like

Microcontroller > tlc > 1360 > led

Title: Re: 3w RGB color bar (BOM w/ TLC5940, Fets, UNL's
Post by: Riva on Feb 01, 2013, 11:46 am
I have built constant current drivers for a 10W RGB LED and it runs for hours quite happily. See here http://arduino.cc/forum/index.php/topic,134827.0.html (http://arduino.cc/forum/index.php/topic,134827.0.html)
Title: Re: 3w RGB color bar (BOM w/ TLC5940, Fets, UNL's
Post by: bobmalaria on Feb 01, 2013, 12:38 pm
Hi,

following Riva's tutorial for a constant current driver, I just finished the prototype for a 10W 350mA RGB LED. works great with PWM and the parts
were relatively cheap. For each channel: a simple NPN transistor, a Logic level mosfet, two resistors. Per channel maybe ~1.5£. The most expensice was the 12V wall PSU that I had to buy.
Title: Re: 3w RGB color bar (BOM w/ TLC5940, Fets, UNL's
Post by: sjim on Feb 01, 2013, 09:52 pm
Would there be any advantage to use this circuit below using ULN2803's ?  Would only need 2 x 2803's  vs 15x1360's (3 per RGB for 5 RGB fixture) is that correct?  My concerns are is performance change w\ multiplexing...etc.  You can reach 300ma with 3v on the 2803's if you look at the spec sheet.

http://www.mikrocontroller.net/attachment/33304/LUXEON_TLC.png

http://www.doyoung.net/video/DATASHEET/PDF/ULN2803.pdf


I did order a few 10w RGB, once I get the 3wRGB driver figured out I'l just change to accommodate the 10w...  I'm new into this but tech enough and detailed so that it's pretty fun doing so....
Title: Re: 3w RGB color bar (BOM w/ TLC5940, Fets, UNL's
Post by: sjim on Feb 01, 2013, 11:46 pm
Posting my learnings here today,

Just discovered WS2803D (in place of the TLC) and it's datasheet says it can handle up to 12V directly so no need for the NPN's in some cases, can drive 6RGB's per chip, serial interface

Here quick breakdown I could use for either 5-6 RGB3w fixtures:

WS2803 = 18 channels (1 IC needed)
TLC5940 = 16 channels (2 IC = 32 channels)
74HC595+ULN2803 (pair) = 8  ( 3 pairs of IC = 24 channels

Using the WS2803 chip (or chips) you don't use PWM to talk to them but a form of serial using 2 digital pins. These 2 pins will talk to all the WS2803 chips (not 2 pins per chip) as there control pins are daisy chained together CKI > CKO & SDI > SDO   (not sure I understand this yet)

The VCC pin on the WS2803 needs connecting to the +5V pin on the UNO and the GND pin needs connecting to the GND pin on the UNO and to the 12V ground. The CKI and SDI pins need connecting to a couple of the UNO's digital pins as these program the WS2803 chip(s).
The IREF needs connecting to the shared ground (preferably not ground through the UNO as I'm not sure of IREF output level)
A couple of capacitors to just reduce potential electrical noise and smooth out loads. I would try one 16V 10uF electrolytic and one 16V 100nF ceramic per WS2803 connected between VCC & ground close to the WS2803

I need to learn more about the high current output of this 2803D IC... sounds like a possible upgrade from the TLC


Title: Re: 3w RGB color bar (BOM w/ TLC5940, Fets, UNL's
Post by: Chagrin on Feb 01, 2013, 11:57 pm

I need to learn more about the high current output of this 2803D IC... sounds like a possible upgrade from the TLC


"WS2803 has 18 output channels, each channel can output up to 30mA constant current." Two more channels but 1/4 the power on any single channel.

As far as price goes the TLC5940 can be had for just as low or better price than the WS2803.
Title: Re: 3w RGB color bar (BOM w/ TLC5940, Fets, UNL's
Post by: cjdelphi on Feb 02, 2013, 12:10 am
I used that rgb mini fader with those 3watt rgb led's it works great just add a resistors ....
Title: Re: 3w RGB color bar (BOM w/ TLC5940, Fets, UNL's
Post by: sjim on Feb 07, 2013, 11:44 pm
With the ZXLD1360, can I directly connect pwm output from an 3ch RGB controller to the 1360?  They're not logiclevel (I think).  If I limit current to 300ma per color, could I then take the Blue from 3 of the RGB's connect to single 1360, do the same for RED, Green...thus needing only 6x1360s for a fixture with 6x3wRGB?  Aka, run colors in series to each 1360 chip separately.
Title: Re: 3w RGB color bar (BOM w/ TLC5940, Fets, UNL's
Post by: johnwasser on Feb 08, 2013, 12:19 am

With the ZXLD1360, can I directly connect pwm output from an 3ch RGB controller to the 1360?  They're not logiclevel (I think).


http://www.diodes.com/datasheets/ZXLD1360.pdf

Yes, you can run the Open Collector PWM signals from your controller to the "ADJ" pin of the ZXLD1360.


  If I limit current to 300ma per color, could I then take the Blue from 3 of the RGB's connect to single 1360, do the same for RED, Green...thus needing only 6x1360s for a fixture with 6x3wRGB?  Aka, run colors in series to each 1360 chip separately.


Because you have Common Anode RGB devices you can't put them in series.  That means you need one ZXLD1360 and all its associated components for EACH color of EACH LED package.  If you buy separate R, G, and B LEDs you can put several in series and run the series off a single ZXLD1360.
Title: Re: 3w RGB color bar (BOM w/ TLC5940, Fets, UNL's
Post by: sjim on Feb 08, 2013, 12:42 am
Thankyou John... that's right, can't do series with CA, I've read so much material I keep forgetting the basics, althought, is this regardless of the driver I use or is there a circuit build possible for CA in series?
Title: Re: 3w RGB color bar (BOM w/ TLC5940, Fets, UNL's
Post by: dtokez on Feb 08, 2013, 01:42 am
I'm afraid not, the nature of CA or CC is that the 3 LED's share either the anode or cathode. This means that it is impossible to wire them in series which would require separate cathodes or anodes per each colour so you could connect them to the next colour.

Hope that makes sense
Title: Re: 3w RGB color bar (BOM w/ TLC5940, Fets, UNL's
Post by: sjim on Feb 08, 2013, 05:39 am
ah, I can see now how it would not be possible... which is why vendors use individual colors led in their washes, floods and bars as it is overall less expensive on the hardware side. I was wondering why RGB's are hardly used in out of the box led fixtures, although, it's just a bit more of a task when having multiple RGBs per fixture.  Alternatively, If I could use a multi-channel IC like the TLC5940 would probably be the preferred route, but, it would need to accept 3 pwm outputs from DMX RGB controller, not sure if it's possible.

In using a switching regulator per color per RGB, what's consider the best choice considering dimming to be important, does the zxld1360 suffice or what other IC's, Fets..etc  I know many others have gone this route so curious as to what would be the best /cost effective way... ULN2003,LM317...etc

I had a lapse,  here's what I would need to do with 1360, as stated by John....
" Yes, you can run the Open Collector PWM signals from your controller to the "ADJ" pin of the ZXLD1360."
Title: Re: 3w RGB color bar (BOM w/ TLC5940, Fets, UNL's
Post by: sjim on Feb 09, 2013, 09:07 am
since my output from the 3chRGB controller... each color output ranging from 12v and below, I will need to regulate before connecting to the ADJ pin bc the zxld1360's ADJ pin max is +6v. It seems the only way to do so is use a NPN transistor so the 1360 only receives voltages from 0 to +6 volts, is this the correct way to do this?  In reading the specs, do I regulate the NPN operational at +6v or is it +2.5v (according to the DC voltage method) ?
+
(1360's specs)
Driving the ADJ input via open collector transistor
The recommended method of driving the ADJ pin and controlling the amplitude of the PWM waveform is to use a small NPN
switching transistor as shown below:
This scheme uses the 200k resistor between the ADJ pin and the internal voltage reference as a pull-up resistor for the
e.

• Drive with DC voltage (0.3V < VADJ < 2.5V) to adjust output current from 25% to 200% of
IOUTnom
• Drive with PWM signal from open-collector or open-drain transistor, to adjust output current.
• Adjustment range 25% to 100% of IOUTnom for f>10kHz and 1% to 100% of IOUTnom for f <
500Hz
• Connect a capacitor from this pin to ground to increase soft-start time. 
(Default soft-start time = 500µs. Additional soft-start time is approximately 500µs/nF)
Title: Re: 3w RGB color bar (BOM w/ TLC5940, Fets, UNL's
Post by: johnwasser on Feb 09, 2013, 01:18 pm

I will need to regulate before connecting to the ADJ pin bc the zxld1360's ADJ pin max is +6v.


No, because the outputs of the RGB controller are Open Collector and the zxld1360 datasheet says you can use an Open Collector signal directly.

"Open Collector" means the output pin is internally connected to the Collector of an NPN transistor.  When the NPN transistor is off the output pin is floating. When the NPN transistor is ON the pin is pulled to ground.  In those cases where you need a HIGH/LOW signal from an Open Collector output you must provide a pull-up resistor.

Since the zxld1360 accepts an Open Collector output as an input it must have an internal voltage source.
Title: Re: 3w RGB color bar (BOM w/ TLC5940, Fets, UNL's
Post by: sjim on Feb 12, 2013, 08:23 pm
Would I a pull-up in this scenario, like a 10k pull-up between ADJ and controller's output?   
would it be close to this model below?
(each color 350ma)

3ch RGB controller output1(12v >)  -> 10kpull-up -> Adj 
10kpullup -> c1=100nF -> Grnd

12v -> Vin -> Rsense(.1ohm) -> RGB(eg.Red) -> 47uH -> Lx

I think also it might better to the use the ZXLS1350(350ma) vs 1360(1a)
Title: Re: 3w RGB color bar (BOM w/ TLC5940, Fets, UNL's
Post by: Chagrin on Feb 13, 2013, 03:43 am

Would I a pull-up in this scenario, like a 10k pull-up between ADJ and controller's output?   
would it be close to this model below?
(each color 350ma)

3ch RGB controller output1(12v >)  -> 10kpull-up -> Adj 
10kpullup -> c1=100nF -> Grnd


The RGB controller output goes to the gate of an NPN transistor, the collector connects to the open collector output, and the emitter connects to GND.
Title: Re: 3w RGB color bar (BOM w/ TLC5940, Fets, UNL's
Post by: sjim on Feb 16, 2013, 06:55 am
How about this config to drive 1x3wRGB (r=2.5v, b/g=3.5v) at 350ma per color

(eg. 3chRGB Controller output for Red(only) from 12vDC > 3ch RGB controller(each separate output to) > NPN > ZXLD1352

12v+ ----47k 5% .25w----\  prevent flicker when power on
R  -------10k -------------/ (gate) BC848(npn)-collector -> ADJ(zxld1352)
B                                   (emitter)--GND           
G

Grnd  ---- power grnd of zxld

Any better way or different part configurations for doing so?  The ZXLD1352 has 1000:1 dimming vs 100:1 for the 1350 (assuming would this give better dimming spectrum)
Title: Re: 3w RGB color bar (BOM w/ TLC5940, Fets, UNL's
Post by: sjim on Jul 06, 2013, 09:34 pm
Can anybody validate this design for a single 3w RGB using a mini 3 ch RGB controller, see attachment.