The VSYS gate control circuit monitors the PPHV and VBUS
voltages and detects reverse current when the VVSYS surpasses V
VBUS by more
than V
RCP. When the reverse current condition is detected, GATE_VBUS is
disabled within tPPHV_RCP. When the reverse current condition is cleared, GATE_VBUS is
re-enabled within tPPHV_ON. This action limits the amount of reverse current that can
flow from PPHV to VBUS through the external N-ch MOSFETs. In reverse current protection
mode, the power switch controlled by GATE_VBUS is allowed to behave resistively until
the current reaches VRCP/ RPPHV and then blocks reverse current from PPHV to VBUS.