ZHCSH31B August 2017 – February 2018 DRV10987
Two options are available for stopping the voltage applied to the motor when the current threshold is reached. If IPDRlsMd = 0, the recirculate mode is selected. The low-side (S6) MOSFET remains on to allow the current to recirculate between the MOSFET (S6) and body diode (S2) (see Figure 21). If IPDRlsMd = 1, the high-impedance mode is selected. Both the high-side (S1) and low-side (S6) MOSFETs are turned off and the current flies back across the body diodes into the power supply (see Figure 22).
In the high-impedance state, the phase current has a faster settle-down time, but that could result in a surge on VCC. Manage this with appropriate selection of either a clamp circuit or by providing sufficient capacitance between VCC and GND. If the voltage surge cannot be contained and if it is unacceptable for the application, then select the recirculate mode. When selecting the recirculate mode, select the IPDClk[1:0] bits to give the current in the motor windings enough time to decay to 0.