i am making this project where i need to turn on the 12v 1amp motor with transistors.
i am using FDP7030BL for this project and for that i am designing a PCB because there are many motors that i need to control with this circuit.
i want this circuit to be as safe as possible and not to blow my arduino or anything else.
Please take a look at my schematics and let me know if i am putting less or excessive resistance on my board, and how much value should be of that resistance please let me know.
Your schematic should look like this. Supply at the top, ground at the bottom, signals move from left to right. The resistance values shown below are appropriate.
If this is being used for PWM I'm not at all keen on the 0.1uF capacitor being across the load; it will significantly increase the current through the FET during switching. If some filtering is needed then an inductance in series with the load would seem more appropriate.
I don't see how that 0.1u cap makes switching any slower. It will take care of a lot of noise produced by the motor, particularly those small spikes caused by switching coils (for brushless) or the brushes themselves. That's a good thing in most situations.
If this is being used for PWM I'm not at all keen on the 0.1uF capacitor being across the load
You might even become a convert if your project fails due to radio frequency noise, as has been recently reported on this very forum.
And just one ceramic cap may not be enough. The Pololu engineers use them on all of their very well designed PWM motor products, and went out of their way to create a blog article on the topic, explaining the problem and the solution.
we recommend you always solder at least one capacitor across your motor terminals. Typically you will want to use anywhere from one to three 0.1 µF ceramic capacitors, soldered as close to the motor casing as possible.
Route your motor and power wires away from your signal lines. Your motor lines can induce currents in nearby signal lines. We have observed voltage spikes as high as 20 V induced in completely separate circuits near a noisy motor.
Ceramic caps, 1 or 3, usually 0.1uF are what every RC modeller was using back in the good old days when we still used brushed motors. And those motors were driven by ESCs using PWM. Seemed to work o.k., certainly much better than if you left the caps off.
