The backup battery is charged from the power path of the VRO pin (output of 3.3-V LDO) via an external diode and resistor. The input of the LDO voltage regulator comes from the internal boost converter. The 1.2-V output LDO and 1.8-V output LDO voltage regulators have a enable pin, V_CTRL. If these outputs are not necessary, V_CTRL should be connected to AGND to save power consumption. The self-power consumption is less than 3 A (maximum) using the backup battery.