Controlling High Power LED's

Using Arduino Project Guidance
1

Hi,

I need to control 24 HPL's with Arduino drawing 800mA each (only one is lit at the time). For the LED's I need to use external power since Arduino can't provide that amount of current from its pins and I have setup done which provides the proper current. Now I need some kind of switch that directs this 800mA current to different LED's that I can control with Arduino. I checked ULN2003A transistor package but it's rated 600mA peak current and all transistor packages I have seen are rated around 500-600mA max. Any recommendations what I should use? I basically need something that has 7 switches to control all the LED's I need.

Could I do this by using two ULN2003A DIP's and directing the current from the driver through 2 collector pins at the time? And for curious cats here is the super simple HPL driver I'm using (for 3W HPL's)

Thanks, Jarkko

2

I have setup done which provides the proper current.

Which I am not going to tell you anything about.

High power LEDs require a constant current drive.

3

Grumpy_Mike:
Which I am not going to tell you anything about.

Because it's not relevant for the question. I have 800mA coming out from the driver and I need to direct it to the LED's with a switch.

4

There are plenty of transistors & MOSFETs that can handle one amp or more. ...Or a relay, but you generally need a driver for the relay and they are bulky.

But usually, the current is switched on & off by the same device that's already built-into your constant current power supply. It's redundant to have a MOSFET or transistor, or other device controlling the constant current and a 2nd device to switch the current on & off. So, it's best to avoid that if you can.

Many LED power supplies have an input for switching/dimming the LEDs ([u]example[/u]). The standard is a 10V control signal, so you have to step-up the Arduino's voltage, but the control signal requires almost no current.

Or, I recently bought a couple of [u]these[/u]. (I haven't used 'em yet.) They are set-up for 300mA so they won't work for you, but you just feed it an on/off logic signal from an Arduino I/O pin, or PWM if you want to dim the LEDs.

I think it might go up to 800mA if you change the (surface mount) resistors, so you can research the specs on the chip if you wish. Or, you can build/buy something similar with an 800mA rating.

5

Thanks DVDdoug. I like this to be rather cheap and compact because it's part of a portable device that runs on 9V battery. So I was hoping to need only one current regulator (because I have only one LED on at once) and the current to be directed to an appropriate LED.

6

TIP-120, but it is a transistor, not as efficient as an FET

if you want to drive with constant current, you can use pwm and monitor current.

7

JarkkoL:
Because it's not relevant for the question.

If you know enough to know it is not relevant then you know enough to solve your problem.

Obviously you don't.

8

JarkkoL:
I like this to be rather cheap and compact because it's part of a portable device that runs on 9V battery.

800mA LEDs on a smoke alarm battery.
Really?
Leo..