How does a low-voltage IPD sense temperature for thermal shutdown?

The thermal shutdown temperature is detected by monitoring the forward voltage (V_F) of a temperature-sensing diode on a chip.

The forward voltage of the diode has a temperature coefficient of roughly -2 mV/°C. The forward voltage of the temperature-sensing diode is compared with the internal reference voltage, and when the forward voltage falls below the reference voltage because of an increase in temperature, the thermal shutdown threshold is tripped to protect the IPD from excessive temperature.