3.8 TI Precision Labs - Motor Drivers: Decay Mode
In order for stepper motors to run smoothly and have a good micro-step resolution, stepper motors require precise current control or regulation. After the output current reaches each micro-stepping current regulation point, the inductive output current will keep the same direction during this pulse width modulation (PWM) off period. The output current drop rate is decided by the coil terminal voltage and the motor back electromotive force (EMF). The decay mode selects the re-circulation current path and determines how fast or slow the current drops once the current reaches the regulation point.