Hello, I'm looking for an alternative to TIP120. Of course, I'm a beginner in electronic.
I read everywhere tutorial suggesting to use TIP120 and then you find that it's draining a lot of current and a MOSFET should be a better choice.
I usually used TIP120 to command 12V solenoids (max 1A).
Thanks a lot!
If they work and you have them in stock, use them.
Make sure they saturate, Vce should be less than 1.4 volts.
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AOI514 is good for 5v on the gate, and cheap. There are a bunch of others in that product line, and comparable products from other manufacturers. The important thing is to make sure they're easily able to handle the current, and that they are logic level.
IRF3708PBF is okay at 3.3v, great at 5.
Put a ~100 ohm resistor between gate and the Arduino pin, and a ~10k ohm resistor between gate and source to keep the fet off while you're uploading a sketch to the arduino (since the pin is floating in that case)
wgh000:
Hello, I'm looking for an alternative to TIP120. Of course, I'm a beginner in electronic.
I read everywhere tutorial suggesting to use TIP120 and then you find that it's draining a lot of current and a MOSFET should be a better choice.I usually used TIP120 to command 12V solenoids (max 1A).
Thanks a lot!
You mean wasting a lot of voltage? Darlingtons only take a small base current, and the load
current you are going to need anyway - its the very large saturation voltage (1V to 2.5V or so depending
on load) that makes darlingtons ineffcient for low voltage circuits.
wgh000:
I usually used TIP120 to command 12V solenoids (max 1A).
The problem is voltdrop. ~1.5volt for a darlington.
A TIP120 is fine for solenoids, because a 12volt solenoid still works fine on 10.5 volt.
Coil current will be 10.5/12 (87.5%) of what it is on 12volt.
Different story for e.g. a LED strip.
A 12volt LED strip has three ~3.3volt LEDs in series and a resistor for the remaining 2volts.
10.5 volt on a 12volt LED strip would result in 0.5volt across the current limiting resistor.
0.5volt instead of 2volt is 25% of the original LED current.
Logic mosfets are needed for LED strips if you don't want dimmer LEDs.
Leo..
So, are you saying me to continue to use the good and old tip120?
I would suggest avoiding the obsolete darlingtons - or at least not buying more of them. For some purposes, probably including yours, they are acceptable, but for other applications they are not, and they'll certainly dissipate a lot more heat than a MOSFET would.
I suggest you use MOSFETs - I suggested a few part numbers above. Digikey has an amazing search tool, as well (that's how I find FETs). You can filter their whole huge selection by package, current rating, voltage rating, and whether they're logic level or not. For driving with the Arduino, you need logic level ones.