The most common use is output over-voltage protection. By connecting a resistor divider from the output to the PROT pin, you can detect if the feedback loop fails:
Below is a conceptual design for output OVP using the PROT pin: bd9766fv protection pin
Whether you are repairing a damaged LCD TV power board or designing a new automotive power module, mastering the BD9766FV protection pin will save hours of debugging and prevent costly MOSFET blowouts. The most common use is output over-voltage protection