This is a follow up question to my previous one,(Transistor selection for 5V LED circuit) where I was (kindly) guided to using a MOSFET to switch on this circuit.

My intention to switch this circuit on/off using a capacitive sensor IC such as this: http://www.mouser.com/ds/2/42/iqs904_datasheet-8785.pdf

At moment I'm still testing on the breadboard. In the diagram below I'v replaced the IC with a simple switch+resistor to represent the output of Pin 3 (presumed to be 3~5 mA @ 5v) The LEDs are 3.6v @ 20mA

The circuit now looks like this:


simulate this circuit – Schematic created using CircuitLab

I'm new to MOSFETS (and actually electronics). From a quick look around it looks like a 2N7002K would work.

Is this the correct choice?


Let's go over the main specs of the MOSFET...

Drain-Source Voltage (Vdss)=60v. You will be subjecting it to 5v, so you're good!

Gate-Source Voltage (Vgss)=20v. You're at 5v, so good.

Drain Current (Id)=300 mA continuous. You are at 100 mA (20 mA for each of the 5 LED's). Good!

Gate Threshold Voltage (Vgs(th))=1.0-2.5v. You'll be driving the gate with either 0.0v or 5.0v, so here again you are good.

I ignored some of the more esoteric specs, which could come into play if you were driving an inductive load like a motor or relay, or needing to have fast switching or high-frequency switching. But for turning some LEDs on or off, this MOSFET will be just fine.


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