How much current can I pull through these mosfets?

[danrogers]

Hi all. I'm trying to work out how much current I can pull through some SOT23 mosfets (TSM2314) https://www.farnell.com/datasheets/1685598.pdf

The power dissipation of them is 1.25w at room temp and I'm going to be running 12v through them - plus driving the gate at 5V. I'm a bit lost with the formula?

 

[MaxHeadRoom78]

You really require a Logic level gate type.
Those are Vgs 12v.
Max.

 

[kubeek]

If you are using them for static switching - either on or off, no fast pwm or the like, then 4.9A right from the first page should be your value, dissipating 0.8W and rising 96°C above the ambient temperature, i.e. really hot but managable.

 

[kubeek]

You really require a Logic level gate type.
Those are Vgs 12v.
Max.

+/- 12V is the absolute maximum, not required Vgs. Not only do they state the max current at 1.8-4.5V Vgs, but they also state Vgs threshold as 1.2V max.

 

[danrogers]

If you are using them for static switching - either on or off, no fast pwm or the like, then 4.9A right from the first page should be your value, dissipating 0.8W and rising 96°C above the ambient temperature, i.e. really hot but managable.

I'm using it for PWM switching yes, from a arduino so I'm not sure what the switching frequency would be? How would that effect the current rating?

Thanks all for the replies - not sure what Vgs means?

 

[ronsimpson]

Thanks all for the replies - not sure what Vgs means?

Voltage from Gate to Source. In your case the voltage the micro computer outputs. 0/5V or (0 and 3.3 volts).

 

[danrogers]

thanks, so basically I can pull 4.9A through them unless the ambient temperature goes crazy?

 

[ronsimpson]

Yes.

 

[alec_t]

N.b. the ratings are for the FET "Surface Mounted on FR4 Board, t ≤ 5 sec."
If you are PWMing the FET it will dissipate more heat than if switched only occasionally. You should reckon on handling less than 4.9A (the specified absolute maximum) for reliability.

 

[mvs sarma]

You really require a Logic level gate type.
Those are Vgs 12v.
Max.

all specifications point to working at Vgs of 4.5, 3,3 and even1,8V

Vgs max is for limit and not for working,
Thus IMHO these devices are really logic level controlled only

 

[Mosaic]

If your switching is > 25Khz, you should use a dedicated MOSFET driver chip to prevent FET overheating due to linear mode transitioning. Otherwise I'd still advise a bipolar transistor like a 2n3904/6 to drive it. Direct from a 20mA max logic gate or uC pin is ok if you're under 10Khz or so.