looking for mosfet recommendations

Hi,

I'm looking for some mosfet recommendations that can be used on 3.3v and 5v systems. Arduino nano and esp modules.

I'll be mainly switching 5v up to 12v. And up to about 5 amps.

I have been switching ledstrips with relays since i did not have mosfets laying around so it's time to do something about that.

I hope some of you can give me some recommendations about your favourite allround workhorse.

You fail to mention the required current rating(s) of the MOSFET(s).

Hi,

I like the RFP30N06LE Power NFET (Low-Side power switching transistor). See it HERE (That has a link to the datasheet)..

MAX of 30A, 60V But usually OK for 10A with 5V on gate and no/small heatsink.

Some good How-To HERE: http://bildr.org/2012/03/rfp30n06le-arduino/

Here's a shot from that page:

There are many other possibilities; someone will add to this...

DISCLAIMER: Mentioned stuff from my own shop...

groundFungus:
You fail to mention the required current rating(s) of the MOSFET(s).

Ah ofcourse, up to 5 amps or so. Updated opening post.

terryking228:
Hi,

I like the RFP30N06LE Power NFET (Low-Side power switching transistor). See it HERE (That has a link to the datasheet)..

MAX of 30A, 60V But usually OK for 10A with 5V on gate and no/small heatsink.

Some good How-To HERE: http://bildr.org/2012/03/rfp30n06le-arduino/

Here's a shot from that page:

There are many other possibilities; someone will add to this...

DISCLAIMER: Mentioned stuff from my own shop...

Thanks i will have a look. 5v on gate you say, so not possible to use with 3.3v arduino boards i guess. Would love to have some that works with both.

So i had a look at the datasheet. I read a bit more about mosfets. Is my following idea right?

With 3.3v at the gate from an esp module, max 10ma output, running a 5v device i could use up to ~20 amps? (Green line)

With 5v at the gate, running a 5v device, ~70 amp? (Red line)

70 amps? Sure, for 80 microseconds. Read all the text on that plot, it is meaningless for normal use.

You’re looking at the pulse behavior of the drain to source voltage when you hit the device with a 80us pulse (0.5% duty cycle max). The drain to source amps on the y axis and gate voltage on the x. The curves represent the d-s voltage at the various combinations of gate voltage and drain current. Useless stuff for non-pulse applications.

You’ll need a small heat sink for 5 amps to keep the temperature rise reasonable since a 47 milliohm on R isn’t as low as you can go with modern devices. You can spend a fair amount of time with the DigiKey parametric search tool finding a best fit device.

Lol theo is what i ment, there are so many graphs so much new terminology... drain to source, d-s voltage.

I will look at the digikey search tool, however not knowing what values to put where makes it confusing.

Farnell gives me 7 fields to fill and all i get is smd parts without heatsinks. I will probably not need more that 2 amps mac but having the option to go to 5 would be nice. Probably not such "allround" option around.

Back to more reading and trying to master this " magic"

Hello, I'm a beginner but I thought I could help out with this.

You can use IRLB8721. It has 16 milliOhm RDSon at 4.5V Vgs.

I have used it myself to control a 2m 12V RGBW LED strip. Adafruit tutorial says it works with 3.3V logic as well.

Will have a look at it thanks

There are pitfalls for the unwary with MOSFET datasheets - many are full of graphs of "typical" response.

Unfortunately "typical" isn't very useful as the variation between devices (concerning any gate voltage) is large,
a volt or more, sometimes +/-1V spread, perhaps 20 to 50% in absolute terms.

If you want guaranteed behaviour you have to use the maximum Rds(on) rating, which will specify
a particular gate voltage or voltages - that's a figure you can rely on for all devices across the full
temperature range given.

Another pitfall is not understanding the various gate voltages.

There's the threshold voltage, the point of full turn-off - this is almost never relevant for anything,
so long as its larger than 0V.
There's the plateau voltage, where the main channel forms and the gate charges up (mid way
through switching),
There's the fully on gate voltage, normally taken to be about twice the typical plateau voltage so
that switch on and switch off are fairly symmetrical in time and both rapid and device variation
is allowed for.

Most logic level devices have threshold of 0.5--1.0V, plateau voltage around 2 to 3V.
Most non-logic level devices have threshold of 2.0--4.0V, plateau at 4 to 7V or so

For large loads its common for gate charge and discharge currents to be in the 0.1 to 1A range,
due to the large capacitance between the gate and channel. Feeble gate currents mean very
slow switching, and this can lead to large losses and heat generation.

Although FETs are voltage switched, practical use of a power MOSFET with PWM requires large
gate currents and attention to circuit layout to reduce stray inductance and reduce interference.

This means it very wise to use a gate driver chip to drive the MOSFET gate - its a tough job
so use the component designed for the job. The faster the PWM and the larger the load on the
MOSFET the more important it is to have tight control of the gate waveforms and to have sufficient
gate drive voltage.

MarkT thank you for the extra information.