Once the adapter is re-inserted and the BQ21040 begins to supply 50uA once again, the voltage across the NTC will double as now there is double the current flowing through the thermistor. A simple algorithm that checks for a large change in VTS can be written on the MCU to be able to recognize this condition as the adapter being inserted. Once this adapter insertion condition is met, the MCU should then stop supplying 50uA and let the BQ21040 handle current biasing the NTC until the MCU detects an adapter disconnect once again. It is also important to ensure that the time period when checking for a large change in voltage to detect adapter insertion is not longer than the thermal time constant of the thermistor. This is to prevent a situation where the device actually enters an environment that induces a rapid temperature change and the MCU falsely detects this temp change as an adapter insertion. If the check time is less than the thermal time constant, the MCU will be guaranteed to detect a voltage jump faster than the thermistor would be able to respond to a rapid temperature change, effectively ruling out any situation where a temperature jump would be misinterpreted as adapter insertion.