When the series switch is turned off during an overvoltage fault at EXT, the INT node becomes quickly pulled up to Vcc through the external pull up resistor. Without this resistor, INT will become high impedance when the switch is turned off.
When the series switch is turned off during an overvoltage fault at EXT, the INT node becomes quickly pulled up to Vcc through the external pull up resistor. Without this resistor, INT will become high impedance when the switch is turned off.