ZHCSI59I July 2009 – May 2018 TPS65070 , TPS65072 , TPS65073 , TPS650731 , TPS650732
UNLESS OTHERWISE NOTED, this document contains PRODUCTION DATA.
There are two inputs to the power path called AC and USB. Both inputs support the same voltage rating but are typically set to a different current limit with AC beeing at the higher limit and USB at the lower. If voltage is applied at both inputs and both are enabled in register PPATH1 (default setting), AC will be preferred over USB. In this case, the deivce is only powered from AC and there is no current from USB. If voltage at AC is removed, the USB input will become and TPS6507x is powered from USB. The current at the input pin AC or USB of the power path manager is shared between charging the battery and powering the system load on the SYS pin. Priority is given to the system load. The input current is monitored continuously. If the sum of the charging and system load currents exceeds the preset maximum input current (programmed internally by I2C), the charging current is reduced automatically. See the electrical characteristics or the register desciption for the default current limit on AC and USB for the different family members.
Figure 27 illustrates what happens in an example case where the battery fast-charge current is set to 500 mA, the input current limit is set at 900 mA and the system load varies from 0 to 750 mA.