In order for charging to occur, the source voltage as measured at the IC's USB or IN pins (factoring in cable/trace losses from the source) must be greater than the VINDPM threshold (but less than the maximum values above) and the source's current rating must be higher than the buck converter needs to provide the load on SYS. For charging at a desired charge current of I_CHRG, V_USBorINx I_USBorIN x η > V_SYS x (I_SYS+ I_CHRG) where η is the efficiency estimate from Figure 7-1 or Figure 7-2 and V_SYS = V_BAT when V_BAT charges above V_MINSYS. The charger limits I_USBorIN to that input's current limit setting. With I_SYS = 0 A, the charger consumes maximum power at the end of CC mode, when the voltage at the BAT pin is near V_BATREG but I_CHRG has not started to taper off toward I_TERM.