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The TPS65510 offers a suitable solution for power switch to select the main battery or the backup battery.

This device automatically selects the power path. It depends on the voltage level of the VO_BT pin. When the main battery is removed, the power path of the VOUT pin is automatically changed from the output of 3.3-V low droppout (LDO) voltage regulator to the backup battery.

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 µA (maximum) using the backup battery.

This device has two indicators. One is CS, which monitors the voltage level of the VBAT pin and VO_BT pin. The other is XRESET, which monitors voltage level of the VOUT pin. These indicators should be connected to CPU/DSP to reset them.

This device reduces the total solution area and extends the lifetime of the backup battery.