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If a transistor works as a 'switch' and I turn it on using a controller (Arduino), how can I burn the controller?

I pass a 5v, 0.02A charge from my Arduino controller to transistor's base. The transistor opens and lets the electricity flow from the collector to the emitter powering on my other larger 40v device.

Can the current get in from the collector into the base? What's the reason for adding a resistor between the controller and the base? so that I don't add 'extra' current from Arduino into the other devices chain? Thanks!

user3578847
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2 Answers2

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Direct connection of Arduino controller to the GATE of power MOSFET is a bad idea.

  1. irf540n needs more than 8 V to become reliably conducting. The controller provides 5 V at most.
  2. irf540n input capacitance is too high for normal logical output.
  3. Taking into account that irf540n is not reliably conducting, it may start oscillations. Its AC gate current may be high in this mode and it is this current that may burn the controller.

You need to use some MOSFET driver to amplify the control signal. There are many suitable components available.

JRE
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Master
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Yes you can use this transistor as a pre-amplifier for irf540. Sure you need to put the reistor between Arduino output and BASE of this PNP transistor. This resistor controls the BASE current.

However this is a "dirty" solution. Values of resistors in BASE and COLLECTOR of PNP pre-amp are critical for correct operation. I suggest using a driver IC.

Master
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  • I'm sorry, I mean what if I use 2n3906 instead of irf540, why do I need to put the resister between the base and the controller? and how can I tell how big should I put it? – user3578847 Apr 12 '16 at 21:39