Smartphones come equipped with USB OTG functionality that allows their USB port to be used not only for charging the phone battery but also allow the smartphone to act as a USB host and deliver power to external accessories such as headphones, pen drives, and so forth. Some smartphones also support a wireless charging path which can also be used to wirelessly share power to other devices. TPS259482x can be used as a bi-directional power switch in such applications as shown in Figure 9-3. For the USB power path, when an external charger is connected at the port, TPS259482x provides a conduction path from IN pin to OUT pin and the battery charger IC is configured to charge the battery and also power the internal circuits. TPS259482x also provides overvoltage and overcurrent protection in this case. In another use case scenario where an accessory such as headphone is connected to the USB port, the phone MCU detects this and the battery charger is configured in OTG boost mode to provide power from battery to the USB port. MCU will also pull down RCBCTRL pin to allow current flow from OUT pin to IN pin of TPS259482x and enables the TPS259482x and establishes a low impedance power path capable of delivering high power to the accessory. Similarly, the TPS259482x also provides controlled bi-directional power flow in the wireless charging and power share sub-system.

Figure 9-2 Smartphone Power Path Example