# Using a mosfet to switch a higher voltage circuit

I have a 25W LED module and I found it to run great at around 13V on my lab PSU.
Now I’d like to switch that LED on and off using my Arduino UNO R3.
I don’t wanna use a relay, I wanna use a mosfet (IRLZ34N).
Now how would I connect that?
Should I use pulldown resistor? Does the LED need a resistor (if so, how much)? (worked just fine without one on my lab PSU without current limiting)

I just tried to design the breadboard circuit using this online tool:

Could that work?

First off a 25W LED at 13V will draw just under 2A, that is way too much for a solderless bread board.
If it is a module then it might contain current limiting circuitry already, please post a link to what you have.

I don't have a datasheet unfortunately, but if it helps, my LED module looks about like this: http://cdn-reichelt.de/bilder/web/xxl_ws/A500/LEDH10W.png
And I counted 25 LEDs inside of it.

If that is too much current, then I will just limit the current on my lab PSU.

In the end I will solder all this on a PCB anyway so it doesn't really matter anyway.

The important thing to me is if the Arduino could toggle the LED circuit or not.

Don't, just solder it

But yeah, the led needs current limiting. A led always need current limiting. A resistor is a form of current limiting but @ 2A isn't not that great... The best solution is to grab a DCDC led driver to do the job. A transistor with heatsink configured as a current limiter may also work but is pretty inefficient. And keep in mind the suppl voltages need to be above the forward voltage of the led. How much depends on the driver you use.

Okay, so generally speaking my circuit is correct?

edit:
The first post had a typo. It said IRLZ43N, but I meant to say IRLZ34N.

I would add a 150 ohm in series with the Arduino pin driving the gate - then you don't have big current
spikes everytime you charge/discharge the gate (MOSFET gates are basically capacitors, and a logic output
isn't really designed to drive a large capacitive load)

felic:
Okay, so generally speaking my circuit is correct?

Think so. Didn't check the pinout of the mosfet because of the stupid Fritzing drawing. But a simple Google search would have revealed that already.

Make sure that your lab power supply and USB power supply are at the same ground potential. I see that you are connecting the grounds togethet in your circuit which could be very very bad if your lab power supply and USB power supply have the ground tapped off at a different potential.

A lab power supply should have no reference to mains... If it does I would not dare calling it a lab power supply...

septillion:
A lab power supply should have no reference to mains... If it does I would not dare calling it a lab power supply...

As long as some chuckle-head didn't short the negative and earth terminals together for no reason (if this is a school lab and not your own equipment). People did that in our labs without having any idea why they thought they were supposed to.

Hi,
OPs pic of LED

Tom....