JAJSFE5C October 2009 – May 2018 TPS65720 , TPS65721
PRODUCTION DATA.
The charger contains a thermal regulation loop that monitors the die temperature. If the temperature exceeds TJ(REG), the device automatically reduces the charging current to prevent the die temperature from increasing further. In some cases, the die temperature continues to rise despite the operation of the thermal loop, particularly under high VAC and heavy system load conditions. Under these conditions, if the die temperature increases to TJ(OFF), the input FET Q1 is turned OFF. FET Q2 is turned ON to ensure that the battery still powers the load on SYS. Once the device die temperature cools by TJ(OFF-HYS), the input FET Q1 is turned on and the device returns to thermal regulation. Continuous over-temperature conditions result in the pulsing of the Q1 FET. Note that this feature monitors the die temperature of the charger. This is not synonymous with ambient temperature. Self-heating exists due to the power dissipated in the IC because of the linear nature of the battery charging algorithm and the LDO mode for SYS.