The TPS4022 device has output overvoltage protection and undervoltage protection capability. The comparators that regulate the overvoltage and undervoltage conditions use the FBx pin as the output sensing point so the filtering effect of the compensation network connected from COMPx to FBx has an effect on the speed of detection. As the output voltage rises or falls below the nominal value, the error amplifier attempts to force FBx to match its reference voltage. When the error amplifier is no longer able to do this, the FB pin begins to drift and trip the overvoltage threshold (V_OVP) or the undervoltage threshold (V_UVP) .

When an undervoltage fault is detected, the device enters hiccup mode and resumes normal operation when the fault is cleared.

When an overvoltage fault is detected, the device turns off the high-side MOSFET and latches on the low-side MOSFET to discharge the output current to the regulation level (within the power good window). After the output voltage comes into PG window, the controller resumes normal operation. If the OV condition still exists, the above procedure repeats.

When operating in dual-channel mode, both channels have identical but independent protection schemes which means one channel would not be affected when the other channel is in fault mode.

When operating in two-phase mode, only the FB1 pin is detected for overvoltage and undervoltage fault. Therefore both channels take action together during a fault.