The phase logic allows to decide the direction of the motor. This logic freezes one side of the bridge (for example, if phase is low, the L6393 on the right side of the diagram on this slide will always have its high side OFF and its low side ON). The half-bridge on the right will switch its high and low side ON and OFF to control the current level. The integrated comparator is used as a peak current comparator. The positive input of the comparator is the voltage across a shunt resistor at the bottom of the H-bridge.  The negative input of the comparator is a voltage reference. When the voltage across the shunt resistor is higher than the voltage reference, the output is grounded, putting the brake at a low level, turning the low side ON and the high side OFF. That creates a decay and the current decreases. The time to start the decay depends directly on the Vreg. If Vreg increases, the current in the H-bridge decreases. So, the DC motor is controlled only by the voltage reference on the CP- pin of the comparator, there is no need for a microcontroller to regulate the torque of the motor.