# Can mosfet driver supply continuous current of 2Amps?

#### AAnkur

Joined Jan 29, 2015
8
Hello

I am using a MOSFET driver circuit to supply power from one section to another section in my design.
I need to pass 2Amps current from one section to another section in my design.
I have selected SI2301 (p-channel mosfet) and SI2302 (n-channel mosfet).

My question is that can a mosfet driver supply a continuous current of 2 Amps?
And for how long can the mosfet driver supply a continuous current of 2 Amps?

Thanks
Ankur

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#### djsfantasi

Joined Apr 11, 2010
8,320

#### AAnkur

Joined Jan 29, 2015
8
Yes I have seen the datasheets.
These mosfets can supply 2A current.

My application is a continuous running application.

However I am trying to understand that for how long can this MOSFET driver circuit pass 2Amps of current continuously?

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#### djsfantasi

Joined Apr 11, 2010
8,320
The SI2302 datasheet lists a continuous drain-source current of 3A. That leaves you some headroom for continuous operation at 2A.

https://datasheetspdf.com/pdf/845346/MCC/SI2302/1

However, I couldn’t find the continuous drain-source current on the p-channel SI230. It did state the maximum d-s current was only 0.75A. That looks like a problem to me.

#### Audioguru again

Joined Oct 21, 2019
4,671
If it is never warmer than 25 degrees C then it can pass 2.6A (Philips and Vishay) continuously when its Vgs is 4.5V.
With 2A in summer then it might get too hot and not last long.

#### crutschow

Joined Mar 14, 2008
29,772
The question is not so much how much current it can drive.
It's what is the Rds(on), which determines how much power it dissipates and how hot it gets.
To avoid having to add a heatsink, you want to keep the dissipation to no more than about 1/2W, which requires an on-resistance of no more than 125mΩ.
Since the SI2302 has an on-resistance of less than a 100mΩ, it should be fine to carry 2A.

If you have the P-MOSFET to control the current, why do you need the N-MOSFET?

#### Audioguru again

Joined Oct 21, 2019
4,671
How can you add a heatsink to that tiny little surface mounted thing?

#### BobTPH

Joined Jun 5, 2013
4,896
Once again we get a solution instead of a problem. What you have shown is a half bridge that can source or sink current, but it doesn’t sound like you need that. What is it you are trying to do?

Bob

#### crutschow

Joined Mar 14, 2008
29,772
How can you add a heatsink to that tiny little surface mounted thing?
Why do you think it needs a heatsink?

#### ag-123

Joined Apr 28, 2017
156
well, i've 'lousy' (cheap aliX,ebay) mosfets that has rather high Ron, they never quite hit the specs
it is quite a problem to try to heat sink these chips. I've some L293D, technically those are worse to heat sink they are bipolar, and dip package so every transistor stage burn at least 1v across it.

back on the topic, i'd guess it is 'similar', which is to try a contraption to heatsink it if it runs hot

#### ElectricSpidey

Joined Dec 2, 2017
2,146
I've always assumed the heatsinking of those small surface mount components was provided by the PCB...am I wrong?

Also after looking at Digi-Key's list of that particular component I would be concerned as to the exact suffix number because they are not all rated for more than 2 amps continuous.

#### BobTPH

Joined Jun 5, 2013
4,896
Can you please explain why you need two MOSFETs to control power to a part of your circuit? Normally this is done with one either on the high side or low side.

Bob

#### Audioguru again

Joined Oct 21, 2019
4,671
You mentioned cheap "aliX and ebay" Mosfets that never meet the specs. Because they are probably discarded factory rejects.

#### ag-123

Joined Apr 28, 2017
156
You mentioned cheap "aliX and ebay" Mosfets that never meet the specs. Because they are probably discarded factory rejects.
on aliX & maybe ebay, you buy a 'transistor', more commonly you get (another) substitute part, it is hard to be assured if you get a real TI part etc. if one gets lucky, it is from Nexperia which has plants in China; Those are normally genuine parts and works quite well.

Especially arbitrary 'transistors', i've tried LM35DZ temperature sensors
I've got a bunch of duds prior, and one keeps wondering if it is just plastic with leads and nothing inside.
real LM35DZ goes for around $1-$2 each on digikey, mouser, farnell element14 etc.
https://www.ti.com/product/LM35
alliX, ebays ones goes for like 5 for a dollar, so it is up to one to gamble.
for these 'transistor' like parts, the safe place to buy is the usual online specialist stockists digikey, mouser, farnell element14 etc.

#### ag-123

Joined Apr 28, 2017
156
I've always assumed the heatsinking of those small surface mount components was provided by the PCB...am I wrong?

Also after looking at Digi-Key's list of that particular component I would be concerned as to the exact suffix number because they are not all rated for more than 2 amps continuous.
i'd guess that's true, and that's provided it is a genuine part and one is running it according to spec and with pcb designs like extra wide/large copper traces etc for the heat sinking links.

The biggest gray area happens when it is a possibly poorer (substitute) part high Rds(on) and one runs it well above specs.
Then all the 'creative heatsinking' comes to play. How do one go about heat sinking a SOP8 to take 2-10 amps loads? assuming that without that it runs well above boiling point of water, on the die within at least.
But i'd guess, for high enough currents, it is possibly cheaper and simpler to do with a real design part that takes the load, with an ordinary heat sink etc.
btw there are a lot of 'cheap 3d printer boards', that I saw use 'SOP8' mosfets, no heat sinks ! and mind that those are driving the 100 watts heated beds at 12v x 10 amps. that's why there are so many 3d printer fires - for the 'cheap' boards.
for 2 amps, i'd guess one can get away with 'creative heat sinking'.

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#### eetech00

Joined Jun 8, 2013
3,147
i'd guess that's true, and that's provided it is a genuine part and one is running it according to spec and with pcb designs like extra wide/large copper traces etc for the heat sinking links.

The biggest gray area happens when it is a possibly poorer (substitute) part high Rds(on) and one runs it well above specs.
Then all the 'creative heatsinking' comes to play. How do one go about heat sinking a SOP8 to take 2-10 amps loads? assuming that without that it runs well above boiling point of water, on the die within at least.
But i'd guess, for high enough currents, it is possibly cheaper and simpler to do with a real design part that takes the load, with an ordinary heat sink etc.
btw there are a lot of 'cheap 3d printer boards', that I saw use 'SOP8' mosfets, no heat sinks ! and mind that those are driving the 100 watts heated beds at 12v x 10 amps. that's why there are so many 3d printer fires - for the 'cheap' boards.
for 2 amps, i'd guess one can get away with 'creative heat sinking'.
Use a higher current, 20A-30A mosfet (lower rdson, less than 70m ohm). At 2A it will barely even get warm.