Saturday 25 June 2016

microcontroller - Transistor Push Pull Stage to drive Mosfet


schematic


simulate this circuit – Schematic created using CircuitLab


Hi,


I want to make a Transistor based Push Pull Stage to drive a 30V Mosfet.


uC GPIO drives the transistor stage with 3.3V and GND to Turn On and Turn Off the Mosfet.


In datasheet, Mosfet has a 1.5V to 2V Threshhold voltage range.


The Problem is:



When GPIO turns the NPN Transistor ON to Turn ON the Mosfet, Gate has maximum 2.7V because of base-emitter diode and this 2.7V is not sufficient to drive Mosfet in Saturation region to allow sufficient current through Load.


I suspect it could also raise the Temperature of Mosfet being driven in Ohmic Region.


My question is:


how could I have more voltage on Gate ? or should I search another Mosfet with very low threshhold voltage ?


Thanks for your suggestions.


EDIT:


Mosfet replaced with that of one with lower threshold voltage.


NPN and PNP transistors changed with those having integrated biasing resistors as well.



Answer



Get hold of a MOSFET driver like the IR2110 and ditch the BJTs because that circuit will never perform well.



enter image description here


I'm sure you can find a single channel version of a similar device.


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