The battery charger is in TTDM when the TS pin goes high from removing the thermistor (removing battery pack/floating the TS pin) or by pulling the TS pin up to the TTDM threshold.

When entering TTDM, the 10 hour safety timer is held in reset and termination is disabled. A battery detect routine is run to see if the battery was removed or not. If the battery was removed then the CHG pin will go to its high impedance state if not already there. If a battery is detected the CHG pin does not change states until the current tapers to the termination threshold, where the CHG pin goes to its high impedance state if not already there (the regulated output will remain on).

The charging profile does not change (still has precharge, fast-charge constant current and constant voltage modes). This implies the battery is still charged safely and the current is allowed to taper to zero.

When coming out of TTDM, the battery detect routine is run and if a battery is detected, then a new charge cycle begins and the CHG LED turns on.

If TTDM is not desired upon removing the battery with the thermistor, one can add a 237k resistor between TS and V_SS to disable TTDM. This keeps the current source from driving the TS pin into TTDM. This creates ≉0.1°C error at hot and a ≉3°C error at cold.