Electronics > Projects, Designs, and Technical Stuff

Driving P-Channel Mosfet

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girishv:

--- Quote from: T3sl4co1l on June 27, 2020, 02:30:19 am ---If the load does not need to be common-ground, yeah, a logic-level FET can do that without the resistor(s) and BJT.

--- End quote ---

I did not want to restrict myself to logic level FET. I thought, driving with BJT would help to keep the BOM cost low as I will have more FET's to choose from.

T3sl4co1l:
Shrug, there's probably about as many logic-level as PMOS.

I suppose the widest option is regular NMOS + gate driver, a single (additional) component solution -- but a bit more expensive than a BJT or two.

Tim

magic:

--- Quote from: girishv on June 27, 2020, 01:02:23 am ---Motor: The motor is brushed DC motor and consumes around 850mA. The +12V supply will come from a AC-DC regulator. The logic level is 3.3V. I am going to use a MOSFET with continuous drain current rating of 7A or more.

--- End quote ---
I don't think it would be hard to find dozens of logic level N-FETs capable of driving 1A with miniscule RDS(on) from 3.3V. Did you really try?

girishv:

--- Quote from: magic on June 27, 2020, 06:18:38 am ---
--- Quote from: girishv on June 27, 2020, 01:02:23 am ---Motor: The motor is brushed DC motor and consumes around 850mA. The +12V supply will come from a AC-DC regulator. The logic level is 3.3V. I am going to use a MOSFET with continuous drain current rating of 7A or more.

--- End quote ---
I don't think it would be hard to find dozens of logic level N-FETs capable of driving 1A with miniscule RDS(on) from 3.3V. Did you really try?

--- End quote ---

I am considering using a NMOS + gate driver as suggested by @T3sl4co1l. I will also checkout the logic level devices.

David Hess:

--- Quote from: aheid on June 26, 2020, 10:43:26 pm ---For the sake of curiosity, was it something like this you meant? Ignore the load specs, I don't know motors.
--- End quote ---

That is exactly it.  I tried to find an example online but they were all for n-channel MOSFETs which I thought would be confusing.

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