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I am trying to use a FET to switch on a boost converter.

schematic

simulate this circuit – Schematic created using CircuitLab

From reading I have found that people like to use IRFML8244TRPBF for logic level FET's. I have about 200mA of current draw from the boost converter.

Will this turn on when I apply 3.3V to the gate? Does anyone have any better part suggestions?

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  • \$\begingroup\$ Where is the boost converter ? Is it represented by the 0Ohm resistor ? Usually, integrated boost converter chips have an enable pin. Why not use it, or choose a part with such a feature ? \$\endgroup\$ – dim Apr 27 '16 at 15:27
  • \$\begingroup\$ I'd consider adding a pulldown resistor (~10k) between the gate and ground to make sure the MOSFET doesn't stay on after it was initially turned on or static charges make it turn on/off randomly. \$\endgroup\$ – Big6 Apr 27 '16 at 15:54
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R2 cannot be 0 ohm; I'm guessing this is a typo. When the Fet turns on it has an on resistance of .024 ohms, so you would essentially short to ground. The part you have will be fine, use the "gate threshold voltage" in the data sheet to choose parts that will switch at your logic level.

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  • \$\begingroup\$ I'm Sorry, That was a typo. It should just be a generic resistor. But that sounds good. I was looking at Vgs and confused myself. Thanks! \$\endgroup\$ – mitch33 Apr 27 '16 at 15:37
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If the boost converter is non-isolating i.e. relies on 0V being common to its input and output then using a MOSFET this way is probably not a good idea. Any current through the MOSFET (when it is on) will cause the 0V on the drain side to be noisy compared to the 0V on the source side. This might mean that some analogue functionality is upset or at least becomes noisy.

As you haven't spelled out what the target circuit is attached to the boosted output and how it might interact with the potentially different 0 volts on the system (due to this way of switching) then I have give this answer as a caution.

Better to use a P channel MOSFET switching the 3V3 thus 0V integrity is maintained.

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