How to Use a 3W Star LED – Kitronik Ltd

15 comments

Introduction

These power LED stars offer an extremely high light output in an energy efficient way. The power LED comes mounted on to special PCB star that acts to draw heat away from the LED, therefore extending its operational life. This makes them perfect for many lighting applications and this sheet explains how.

Technical Information

Forward Voltage:	3.5V – 4.0V
Angle:	110 deg
Luminus Flux (lm):	160 – 200
Colour Temp	6000K – 7000K

Mechanical Information

Ordering

		Description:
		3W Warm white power LED star
		Stock Code:
		3548

Using the LED

The LED is a 3W LED and the forward voltage is rated at 3.5V to 4.0V so for the purpose of the calculations a forward voltage of 3.7V is used. The typical current of the LED will therefore be 810mA (from Power = Current x Voltage). The power source used with the LED must therefore be able to deliver at least 810mA. Since most power supplies will be higher than 3.7V a current limit resistor will be required. The next page shows an example of using this LED with a 5V power supply. The resistor also needs to handle 810mA flowing through it and as a result will need to be a power resistor. Please note that during use both the star LED and the resistor will get hot and shouldn't be touched. The LED has markings for ‘+’ and ‘-’ as indicated below:

how_to_use_a_3w_warm_star_led_3

Single LED powered by a 5V wall block

		Parts List:
		5V wall block PSU
		(2265)

		3W star LED
		(3548)

		2.2 Ohm power resistor
		(3009-2R2)

PLEASE NOTE: The resistor value (and power rating) listed have been calculated for the specific configuration demonstrated in this datasheet. If you make any alterations to the configuration listed, you must ensure that you use a suitably rated resistor of the correct value.

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Kitronik's suggested additional learning

Which Resistor Should I Use with my LED?

LED brightness is controlled using a current limit resistor to drop some of the battery voltage, calculate the resistance using the formulas in this guide. A worked example shows the calculation used to work out the resistance to accompany an LED in a typical circuit using a 9V battery.

Tags: Electronic tutorials

15 comments

Amit Chaudhry

09 September 2019 at 12:58pm

Thanks a ton, 3W Star LEDs are brighter than standard incandescent or halogen light bulbs. And by the way, they are extremely energy efficient which is an icing on the cake.

Mark Donnison

18 July 2019 at 11:03am

Hi Deepak, You could power it with standard batteries, though you would have to adjust your resistor value accordingly. A fresh set of batteries would supply slightly more than the LED is rated for but slightly less than the example shown. Without specific testing, I couldn't say how long the batteries would last, though I suspect it will be less time than you would like.

Deepak

17 July 2019 at 21:39pm

Hello! I was wondering if I could power this LED star with 3 AAA Duracell batteries. Would this be possible? if so approximately how long would it last? Thank you for this tutorial!

Mark Donnison

13 March 2018 at 12:57pm

Hi Dennis, The forward voltage is 3.5V – 4.0V. You can find this info and more on this datasheet. https://www.kitronik.co.uk/pdf/Using_a_Kitronik_3W_star_LED.pdf I hope this helps.

Dennis

10 March 2018 at 17:59pm

I'm trying to figure out what resistor I need using an online resistor calculator. I need more data on this LED. What is the forward voltage? I see that the forward current is 800mA.

Rob Haywood

02 May 2017 at 15:25pm

Hi John, That's far beyond the capacity of anything we sell. Good luck in your search! Rob

John

26 April 2017 at 10:27am

Hi I'm currently trying to repair a light pack it has 25 of these led in a row the power pack has blown and I'm trying to figure out what will work It's running from the mains 240v the pack that was on was 50-100v 550-600ma I can't find one the same so any help would be greatly appreciated John

Mark Donnison

07 November 2016 at 14:51pm

Hi Moriam, As you guessed, knowing the voltage and the current are necessary for working out the resistor values you will need.

Moriam

07 November 2016 at 14:23pm

Hi Rob, I have found this post to be very useful but I am currently trying to work out how to find an appropriate resistor for my LEDS. I'm wiring LED lights from scratch for a project but I'm not sure resistor I would need. I have 3W and 0.5W. Is the resistors all dependant on the power source? Thanks Moriam

Mark Donnison

04 July 2016 at 16:01pm

It would work with a 2.2 ohm wire wound resistor.

john

18 June 2016 at 12:05pm

Hi there, could i connect 3 of these in series with a 12v supply and a 5 ohm resistor?

Rob Haywood

01 February 2016 at 09:34am

Hi Aaliyah, The LED will get very hot if in a confined space with no way for the heat to escape. If your design really does need to have it confined then consider mounting it to a conductive surface to help dissipate the heat. Rob

Aaliyah Ross

29 January 2016 at 09:28am

I'm a student working on a GCSE project for Product Design, I have read through the information about how to use a 3W Star LED light. I know that it does get hot but would that be suitable in a confined space. if so what are the possible consequences of using the 3W star LED in a confined space. Thanks

Rob Haywood

02 November 2015 at 10:07am

Hi Allen, Although technically the resistor could be changed to allow for the extra power, the connector itself is only rated to 500mA, which is what a USB port will comfortably output. The 3W LED draws 800mA so I would advise against this. Rob

Allen Fitzpatrick

26 October 2015 at 09:14am

Hi Guys, correct me if I'm wrong but could I substitute this component for the 1W star LED in the lighting kit you provide with the breakout board? Looking to give my students a few more options for their design work.