SLVSEE8B November 2019 – May 2021 DRV8899-Q1
During fast decay, the polarity of the H-bridge is reversed. The H-bridge will be turned off as current approaches zero in order to prevent current flow in the reverse direction. In this mode, fast decay only occurs during decreasing current. Slow decay is used for increasing current.
Fast decay exhibits the highest current ripple of the decay modes for a given tOFF. Transition time on decreasing current steps is much faster than slow decay since the current is allowed to decrease much faster.