EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: help_me_pick_username on November 16, 2019, 02:50:29 am
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I want to fully drive a 30N06L MOSFET. I have an ESP8266 driving a 10w LED through the MOSFET. The ESP has 3.3v logic levels, and the LED runs at 12v. I am controlling the LED by PWMing the MOSFET gate. My problem is, the 3.3v output level of the esp does not seem to be enough to fully saturate the MOSFET output.
I'm pretty sure that a dedicated MOSFET driver IC is the solution to this, but since I don't have any, and I don't want to wait another few weeks for it to arrive from online, I was wondering if there was some other solution to my problem. (Can I maybe use a BJT to drive the MOSFET at a higher voltage level...?)
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The datasheet of your 30N06L Mosfet shows that it works fairly well when its Vgs is 5V but gives full power when the Vgs is 10V. Some of them work poorly with a Vgs of only 3.3V.
A gate driver IC is not a voltage booster generator, instead it is a circuit that can produce a fairly high current that can quickly charge and discharge the high gate capacitance at a high frequency without boosting the gate voltage.
If you have a power supply that is a littler higher than 5V or 10V then a transistor might be able to be driven from the 3.3V signal and give 5V or 10V pulses to the Mosfet gate.
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I have a 19v power source powering the whole thing. So should I just be able to drive the MOSFET with a signal from a transistor?
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With the high voltages involved here, it seems the safe transistor to drive from the ESP8266 would be an NPN. And all that NPN can really do when you turn it on is ground its collector. To me, that strongly suggests using a P-channel mosfet, which would turn on and apply the full 12V to the LED when its gate is grounded by the NPN collector. It's not obvious to me how you would make this work using another transistor to drive the N-channel mosfet. I'd like to see a schematic of how that would be done.
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