Unipolar 4 Phase Stepper Motor Controller
To sense and control the current in stepping motors and other similar devices, we can use a linear integrated circuit like L6506.
The chip set forms a constant current drive for inductive loads and performs all the interface functions from the control logic through the power stage when used in conjunction with power stages like the L293, L298N, or L7180.
Not only in two phase bipolar configurations, but L6506 also can be used in four phase unipolar motor configurations. L6506 used in conjunction with the L298N in a 2 phase bipolar stepper motor application shown in figure 1. A similar 4 phase unipolar application is shown in the figure. [Source: STMicroelectronics Application Note]