Hi all,
In my project I'm using an RGB 12 V strip of leds.
Each color is driven by a PWM Arduino Pin, through a Mosfet IRF 530.
So I built a little shield with 3 Mosfet,
something like this:
Now, I need to miniaturize as such as possible the shield, so I'm wondering if it is possible to replace the Mosfet with some other TINY component. My knowledge about electronic props is very poor.
Thanks a lot
Maybe with a smaller MOSFET?
How much current does it need to handle?
Ahahahahah! You are right! 
The strip is about 1 meter long.
Given that I never use white light, I think I'm reasonably below 1 ampere (I'll check!).
About "smaller Mosfet", do you have any advice?
As I said, my Knowledge about electronic props is poor
(I always used IRF530)
Thanks!
What matters is the per-channel current, since each channel has it's own fet (right?)
1m is probably under an amp per channel - You can easily get SOT-23 MOSFETs that will handle that; you don't even need to look at the top of the range. SI2302's can be had for like 3 cents each on ebay, and they should be able to handle ~1A no problem. You can also search for SOT-23 n-channel mosfets on digikey and use their sorting/filters to find many many other candidates.
Try switching to other mosfets for your projects.
The IRF 530 you normally use is not a "logic" fet.
Leo..
No, it's not. I don't know why it's so popular - I think it's just because they recognize it because all the chinese mosfet modules use that or the 510. It kinda works at 5v on gate, though.
valerio_sperati:
Now, I need to miniaturize as such as possible the shield, so I'm wondering if it is possible to replace the Mosfet with some other TINY component. My knowledge about electronic props is very poor.Thanks a lot
DPAK or DPAK2 packages are hand-solderable but a lot more compact than TO220.
There are many smaller (but harder to solder) package sizes too.
Pick a logic-level MOSFET with 20 or 30V rating and Rds(on) <= 50 milliohms. Find a
decent supplier that stocks 100,000+ component lines and you'll have a wide choice of
device. That depends on which territory you are in.
That Jerome guy has his FETs wired wrong, as several pointed out in the Comments there - some have the Gate pulldown on the Gate and some on the Source.
(He never addressed the matter.)
Depending on the current required, you may be able to use FET drivers (MIC4427 et al.) instead.
Ok, thanks a lot for your informations.
As I understand, the Mosfet I used till now (IRF 530) is a "TO-220" package,
while the suggested SOT-23 is a "DDPACK" package.
I'll try with the SOT-23.
Thanks again
SOT-23 is a much smaller package, rice grain size.
DPAK is almost as large as the TO 220, but surface mount.
You can see IRF530 package sizes here. SOT-23 does not appear to be an option.
It's not that small - see the 3.3V regulator on the Uno.
What you really want is Logic level, Low Rds, N-channel MOSFET to sink current and be controlled by Arduino output. I like AOI514 for thruhole:
If you want SMD:
I just found a few IRLM6401 P-channel Mosfets. Would they be suitable in this application? I get the feeling they're designed for 1.8v logic level (from the datasheet), but I'm still having a hard time reading transistor datasheets. Here's a typical datasheet for these so-23 parts :
http://www.irf.com/product-info/datasheets/data/irlml6401.pdf
Thanks,
jimmy
That device will work at 5V. Just note that the gate is very sensitive to over-voltage (+/-8V will
trash it), so it will also be very static-sensitive, use proper handling precautions and make sure
the 5V supply is decent.
You'll note the on-resistance is a lot higher when driven from 1.8V, at 5V drive you get 50 milliohm,
but at 1.8V drive that becomes 125 milliohm