If the controlthat controls the is a or steper digital components so it’s good for every port that controls the stepper circuit is given a buffer first so as not to burden port or control circuit is used. As in the following image path of this control can be digitally controlled using a with input signals to the component that serves as a buffer as shown below. In the picture below is only shown one part to control one stepper motor coil. There are two alternatives that is by using a buffer terlebuh first or use the FET, which has a very high input impedance, as a component of the switch. Voltage V motor not necessarily always equal to the voltage VCC to the microcontroller. Therefore used a buffer component which has an open collector output so the output can be in the pull-up to the desired voltage.
Examples of Stepper Motor Driver Circuit
R pull-up of 470 will give a current of 10 mA to the base of transistor Q1. If Q1 has a gain of 1000, the current that can diliewatkan is about several amperes, depending on the large currents drawn by the stepper motor coil. This current must be smaller than the current IC is allowed.
For FET components can be used IRL540 components that can stream flow to 20 A and able to withstand voltages up to 100V back. This is caused by the FET is able to absorb the voltage spikes without protection diode. But these components require a large heat sink and should be good enough in terms of heat absorption. It is better if used capacitors to suppress the voltage spike caused by the switch transitions from on to off.