SLVSB64I November 2011 – March 2018 TPS65217
Whenever the battery voltage decreases to less than the recharge detection threshold (VRCH), the sink current for battery detection (IBAT(DET)) is pulled from the battery for the battery detection time (tDET) to determine if the battery was removed. The voltage on the BAT pin staying above VLOWV voltage indicates that the battery is still connected. If the charger is enabled (the CH_EN bit set to 1b), a new battery charging cycle starts.
When the BAT pin voltage is decreasing and less than the VLOWV voltage in the battery detection test, this indicates that the battery was removed. The device then checks for battery insertion by turning on the charging path and sources the IPRECHG current out of the BAT pin for the tDET time. Failure of the voltage to increase to greater than the VRCH voltage indicates that a battery has been inserted, and a new charge cycle can start. If, however, the voltage is already greater than the VRCH voltage, a fully charged battery was possibly inserted. To check for this case, the IBAT(DET) current is pulled from the battery for the tDET time and if the voltage falls below the VLOWV voltage, no battery is present. The battery detection cycle continues until the device detects a battery or the charger is disabled.
When the battery is removed from the system, the charger also flags a BATTEMP error which indicates that the TS input is not connected to a thermistor.