# Electrical Switch for LED’s (Providing enough MOSFET gate voltage)

I am designing a circuit to independently control (ON/OFF) up to 8 LED strips. So 8 independent channels

The LEDs are of a single color (Not RGB). LED’s are also rated 12V.

The controlling signal is from a 5V Microcontroller (maybe 3.3V later on).

The maximum continuous current possible for a single channel is 2A (1A is an option). A major constraint is the size of the final PCB layout. As such I have chosen to use N channel MOSFETS as the switching device.

Another constraint is that all parts will have to be sourced from ALIEXPRESS, with a low Bill of Materials cost.

NOW TO MY QUESTION:

Most of the low cost mosfets need a gate voltage of about 10V or greater to efficiently turn on the MOSFET (archive low Rds).

I found an Ideal product from Microchip (MIC4468) that fits the application. However, it seems to be on the high side in terms of cost.

Another solution I was looking at was to use level shifter circuits. I found CD40109B which I can design around. I will like to know if it is good practice to use a generic level shifter IC like the CD40109B to drive MOSFET gates.

Also any recommendations and alternate solutions are welcome.

• why do you think the parts from aliex are intrinsically cheaper than from a established distributor like mouser or digikey? If it is a hobbyists project (low volume) some more cents for for your fets won't add up much in total cost. If it is a high volume production, you probably don't want to fiddle around with likely conterfeit components. Feb 3 '20 at 14:13
• @Ariser ALIEXPRESS is preferred choice because of accessibility. Assembly of circuit will be done in West Africa. FARNELL is my go to source. Feb 3 '20 at 14:21
• IRLZ44N is cheap and can switch 2A w/o a heatsink. Feb 3 '20 at 20:54

Look for "logic level mosfet".

Don't be guided by the $$\V_{GS(th)}\$$ value (or look for $$\V_{GS(th)} < \text{about } 3.3V/2\$$), but rather check the conditions for $$\V_{GS(th)}\$$ given for the $$\R_{DS(ON)}\$$ parameter.

Below is a visual explanation of the text above.

This is not a product recommendation: product recommendations are off-topic on this site.

• Thanks. I came across this MOSFET, but was a bit hesitant because of the package size (No heat sink attachment). Can it dissipate graciously the heat generated when conducting 2A of current ? Feb 3 '20 at 15:06