Stepper motor control circuit using high-power field effect transistors

High-power field-effect transistors can also be used to control stepper motors . Since high-power field-effect transistors themselves have no isolation
effect, in order to prevent high-voltage interference and damage to the computer system when used, add one between it and the computer system. level opto-isolator. The circuit using
high-power field effect transistors to control the stepper motor is shown in Figure 27-37.   
    In the figure, when a certain control output terminal (such as PAO) outputs a high level, it changes to a low level through the inverting driver 7406, causing the
photosensitive transistor at the output end of the optoelectronic isolator to saturate and conduct, thereby causing the upper end of the resistor ruler l' The output is high level (close to Ⅵm), which controls the field effect transistor to turn on and
energize phase A of the stepper motor. On the contrary, when PAO is low level, the field effect transistor is turned off and no current flows through phase A. By changing
the power-on sequence of the three phases A, B, and C of the stepper motor , the stepper motor can be controlled.