SLVS979C October 2009 – May 2018 TPS65720 , TPS65721
PRODUCTION DATA.
The charger automatically detects if a battery is connected or removed. Once a charge cycle is complete, the battery voltage is monitored. When the battery voltage falls below VRCH, the device determines if the battery has been removed. A current, IBAT(DET), is pulled from the battery for a duration tDET. If the voltage on the BAT pin remains above VLOWV, it indicates that the battery is still connected, but has discharged. If <CH_EN> = 1, the charger is turned on again to top off the battery. Recharge cycles are not indicated by the <CH_ACTIVE> Bit.
If the BAT voltage falls below VLOWV during the battery detection test, it indicates that the battery has been removed. The device then checks for battery insertion. The FET Q2 is turned on and sources IPRECHG out of BAT for the duration of tDET. If the battery voltage does not rise above VRCH, it indicates that a battery has been inserted, and a new charge cycle begins. If the voltage rises above VRCH, it is possible that a fully charged battery has been inserted. To check for this, IBAT(DET) is pulled from the battery for tDET. If the voltage falls below VLOWV, a battery is not present. The device continuously checks for the presence of a battery.