I'm trying to put together my own board so to speak for plugging in a nano. Part of what I'm trying to do with this board is incorporate a mosfet simple power switch transistor (think IRF520) to control a power strip of LEDs (on and off). I have gone through tons of sites trying to education myself on what components to pick up that will be compatible with what I'm trying to accomplish.
What is the choice here of a SMD transistor that can control up to a 1 amp load at 12v with a 5v digital control signal?
You need a "logic level" MOSFET rated for more than 1A. (The IRF520 is not logic level. It can't turn fully-on with only 5V.) [u]Here's one[/u] I just found by Googling.
Just FYI - Although a MOSFET is a type of transistor, we usually don't call it a transistor because when you say "transistor", people think of a regular bipolar transistor. A regular transistor can work (in a slightly-different circuit) but in power switching applications they generally run hotter and can't handle as much current.
Would I be wrong in saying at these low voltages, the component should stay pretty frosty. The amps are going to be very low, so it shouldn't need cooling.
When choosing a MOSFET (there are 10's of thousands of devices available, I just use parametric search to
choose one) the key parameters are:
max drain-source voltage
Rds(on) value (on-resistance)
The Vgs needed to achieve the Rds(on) - this is always given with the on-resistance, sometimes there's several.
p- or n- channel
package style.
Nothing else matters normally. You compute the power dissipation from on-resistance and the current,
checking that's low enough for your heatsinking (or lack of it).
If the device is logic level there will be an Rds(on) rating for Vgs = 5V (or less)
The threshold voltage is NOT the voltage to switch-on. Ignore it.
The current rating is simply the absolute max power rating in disguise, normally you'll never even be close to it.