Controlling 13 3W LEDs using Arduino

Hello, people! I'm developing a lamp that aims to simulate the sun (it slowly turns on the morning and and slowly turns off in the late afternoon). It uses 13 3W LED lamps that would need to stay on for the whole day (I'm already researching about heat dissipation too). I've been making a lot of research lately and apparently I would need to use a device called CAT4104, that is a constant current LED driver. The problem is that this device is really expensive and I would need to use 4 of them, because I'm going to divide the 13 lamps in 4 groups, so each of them can be individually controlled by the user. I would like to know if it's possible to use a simple MOSFET to control all of these lamps or if there are any other devices for me to use instead of the CAT4104. Thanks in advance for your attention!

LEDs are current driven so you need some form of current limiting - LED drivers should be pretty cheap nowadays considering how ubiquitous they are.

Do a search on eBay, Amazon, etc and you'll find heaps of complete LED drivers that are pretty cheap. Do find one with PWM control so you can actually control the brightness of your LEDs. Trying to control the supply current or output current of such a driver using PWM is a bad idea.

Heat is the worse thing for LEDs, keep them cool and they stay happy. You can use PWM quite effectively to do what you want. There is no such thing as a simple MOSFET however it would be my choice. You are looking at about 40 Watts total, so a Possibly a 15A 12V power supply would do the job with some cushion (head room) to spare. Depending on what you can afford I would go to something in the 30 Amp or larger range on the MOSFETs, to keep the heat down. If the RDSon is low enough you will not need a heat sink. Be sure to properly drive them, look at the data sheet and be sure they are saturated with some voltage to spare (Vgs). UIS rated devices would be nice but unless long wires are involved that would not be an issue. The CAT4104 will not do what you want, did you read the data sheet and determine how many amps you need? Simply PWMing the leds would do good and the current would be relative constant. You have a voltage drop across the leds, put enough in series to hopefully get to about 10 volts, calculate the resistance and place it in series. The current will not change much but the average will be dependent on the PWM duty cycle.

I offer an 8-channel N-MOSFET board with Logic level, very low Rds parts.
https://media.digikey.com/pdf/Data%20Sheets/Alpha%20&%20Omega/AOD_I518.pdf
or
http://aosmd.com/res/data_sheets/AOD424.pdf
I have to look to see what I have on hand.
Can control by driving the gates directly, or be sending data to a shift register.
If shift register, can daisy chain 2 of them.

At 600mA, they won’t even get warm. P = I^2 x Rds = 0.6 x 0.6 x 0.005 ohm = 1.8mW.
I don’t know if I’d recommend a simple resistor for current limit control.

These boards were set up for direct drive, which would be good for PWM drive from a Mega or similar if you were supplying 13 PWM signals.

Hi, Welcome to the forum.

Please read the post at the start of any forum , entitled "How to use this Forum". OR http://forum.arduino.cc/index.php/topic,148850.0.html.

Can you please post a link to data/specs of the LEDs? 13 into 4 groups, 3 ,3 ,3, 4 ?

Using them in groups is no problem, just making sure the current is within the LED spec.

You could google constant current LED driver with PWM control

There are some chips that are able to do most of the current control stuff for you.

Tom.... :)

gilshultz: Heat is the worse thing for LEDs, keep them cool and they stay happy. You can use PWM quite effectively to do what you want. There is no such thing as a simple MOSFET however it would be my choice. You are looking at about 40 Watts total, so a Possibly a 15A 12V power supply would do the job with some cushion (head room) to spare.

That's just ridiculous overkill. 180W to drive 42W worth of LEDs. Same for your suggestion of MOSFETs, makes no sense.

Just PWMing LEDs is again terrible advice, without current limiting you will break stuff very quickly.

We need detailed specs for detailed suggestions. 13 LEDs can not be put into equal groups, 13 in series probably takes about 40V (assuming 3 per LED). That's well within reach of common LED drivers.

wvmarle: LEDs are current driven so you need some form of current limiting - LED drivers should be pretty cheap nowadays considering how ubiquitous they are.

Do a search on eBay, Amazon, etc and you'll find heaps of complete LED drivers that are pretty cheap. Do find one with PWM control so you can actually control the brightness of your LEDs. Trying to control the supply current or output current of such a driver using PWM is a bad idea.

Thanks for the tip! I'm going to make some more research about them

TomGeorge: Hi, Welcome to the forum.

Please read the post at the start of any forum , entitled "How to use this Forum". OR http://forum.arduino.cc/index.php/topic,148850.0.html.

Can you please post a link to data/specs of the LEDs? 13 into 4 groups, 3 ,3 ,3, 4 ?

Using them in groups is no problem, just making sure the current is within the LED spec.

You could google constant current LED driver with PWM control

There are some chips that are able to do most of the current control stuff for you.

Tom.... :)

Hello and thank you!

I've been following the datasheet present on the AliExpress page for the LEDs (I'm going to post the link and also write the specs here). Regarding the groups, i'm probably going to make something like 6, 3, 2, 2 or 9, 2, 1, 1, because I would need to control each color separately.

About the LEDs, I'm going to use 3 warm white, 6 cool white (3W, 3-3.4V, 600-700mA), 2 blue, 1 red (3W, 3-3.4V, 400-500mA) and 1 ultraviolet (we are still searching for it). I'm going to post the link for the website where I found the datasheet at the end of the post (unfortunatelly, it is necessary to scroll down the page a little to find it).

I'm also going to do a little more research on LED drivers to see if I find something nice. Thanks for the advice!

Thank you all for your answers, you people are really kind!

The webpage with the datasheet: https://pt.aliexpress.com/item/32831596858.html?cv=47843&af=1424725&utm_campaign=1424725&aff_platform=api-new-hotproduct-download&mall_affr=pr3&utm_medium=cpa&aff_trace_key=3f0ee95de958454b92db07b1e57df410-1610415070637-07607&dp=7bd33334b0fe95917d70998fc5628ad4&terminal_id=f6aeb6743d3c49fbaa744b36314288b9&tmLog=new_Detail&utm_content=47843&utm_source=admitad

Oh, and I forgot to say that I'm probably going to use a 24V power supply to power everything.

Are you planning on lighting them all at the same time, or do you need individual control of each LED or each colour of LED?

wvmarle: Are you planning on lighting them all at the same time, or do you need individual control of each LED or each colour of LED?

I'm planning on having individual control over each color.

Ideally you would use constant current drivers like these.

“Three signal inputs are provided for dimming control. You can use the PWM signal from an Arduino or your favorite microcontroller to dim each channel individually, or you can tie them all to the same PWM for simultaneous dimming. Dimming can be done by an analog voltage (20%-100% of max current by varying voltage from .5V-2.5V) or by PWM (so long as PWM minimum voltage is less than .4V and maximum voltage is more than 2.4V) for a full 0-100% range. A small jumper is provided for each channel to allow you to increase the drive strength from 330mA to 660mA.”

Each has a AL8805 HIGH EFFICIENCY 36V 1A BUCK LED DRIVER
so it meets your 24V/600mA requirements:

The

solidliquid: Hello, people! I'm developing a lamp that aims to simulate the sun (it slowly turns on the morning and and slowly turns off in the late afternoon). It uses 13 3W LED lamps that would need to stay on for the whole day (I'm already researching about heat dissipation too). I've been making a lot of research lately and apparently I would need to use a device called CAT4104, that is a constant current LED driver. The problem is that this device is really expensive and I would need to use 4 of them, because I'm going to divide the 13 lamps in 4 groups, so each of them can be individually controlled by the user. I would like to know if it's possible to use a simple MOSFET to control all of these lamps or if there are any other devices for me to use instead of the CAT4104. Thanks in advance for your attention!

Although everything is relative, the CAT4104V-GT3 isn't that expensive: Digikey shows $1.83 (Canadian dollars; USD will be considerably less) for qty 1. You could get four of them for less than ten bucks.

See digikey.com part number CAT4104V-GT3OSCT-ND

You'd need some SOIC adapter boards to mount them (or get creative in how you mount and wire them...)

Seems like a pretty sweet, simple solution if it meshes with all the other aspects of your design.

CrossRoads: Ideally you would use constant current drivers like these. https://www.sparkfun.com/products/13705 "Three signal inputs are provided for dimming control. You can use the PWM signal from an Arduino or your favorite microcontroller to dim each channel individually, or you can tie them all to the same PWM for simultaneous dimming. Dimming can be done by an analog voltage (20%-100% of max current by varying voltage from .5V-2.5V) or by PWM (so long as PWM minimum voltage is less than .4V and maximum voltage is more than 2.4V) for a full 0-100% range. A small jumper is provided for each channel to allow you to increase the drive strength from 330mA to 660mA."

Each has a AL8805 HIGH EFFICIENCY 36V 1A BUCK LED DRIVER so it meets your 24V/600mA requirements:

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Thank you so much! I'll take a look at that component and try to learn how it works. It seems to be a very good solution. And I will also start posting printscreens of datasheets to avoid posting links hehe. Thanks for the tip about the driver!

Blackfin: The Although everything is relative, the CAT4104V-GT3 isn't that expensive: Digikey shows $1.83 (Canadian dollars; USD will be considerably less) for qty 1. You could get four of them for less than ten bucks.

See digikey.com part number CAT4104V-GT3OSCT-ND

You'd need some SOIC adapter boards to mount them (or get creative in how you mount and wire them...)

Seems like a pretty sweet, simple solution if it meshes with all the other aspects of your design.

Thank you! I think maybe the shipping price along with the exchange made it become more expensive, since I'm not from north america. But I will take a look at that site, since I haven't found it before. Thank you for the SOIC adapter tip too, since that was another thing that I didn't know how to solve!

solidliquid: And I will also start posting printscreens of datasheets to avoid posting links hehe. Thanks for the tip about the driver!

In general best to post the link (as well). Datasheets are often many pages long, and unless you know exactly which parts are important chances are you're posting the wrong or incomplete bits.

wvmarle: In general best to post the link (as well). Datasheets are often many pages long, and unless you know exactly which parts are important chances are you're posting the wrong or incomplete bits.

Oh, ok. That makes sense. Thank you very much for the tip!