# How to calculate if mosfet doesn't need gate drive IC and heatsink

#### uzairali001

Joined Sep 8, 2015
8
I'm trying to build controller circuit for RGB led strip, I will be using esp32 and it will provide 3.3v on GPIO output so I wonder whether should I get lower VGs mosfet or do I need mosfet driver IC. I'm just hobbyist so I don't much about mosfet (but willing to learn more) so please correct me if I'm wrong. My load will have 2amps each channel for full brightness, Lets take AO3400 for example it has 52mΩ for VGS=2.5V and VGS(th) is 1.4 so this should be suitable with 3.3v right?
For Heatsink:
TJ(max)-TA/Rth
= 150-50/125 = 0.8 w
it can dissipate upto 0.8w without heatsink right?
And my load is R * I^2 = 0.052 * 4 = 0.208 w
looks like I can use this mosfet without heatsink right?
Since it will be using with PWM signal so is there anything I need to add in calculation formula?
Also when do I need mosfet gate driver IC

I've also asked similar question on : StackExchange : and got great answer but to be honest I've got overwhelmed by the information

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#### marcf

Joined Dec 29, 2014
295
According to the data sheet for the A03400A, this part is going to have trouble delivering any current at 1.4Vgs.

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#### ericgibbs

Joined Jan 29, 2010
19,091
hi,
With a Vgate of 3V the Ao3400A MOSFET will be fully On, also 0.2W should not be a problem, its rated at 0.9W at 70C
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