SLVSD95 November 2016 TPS25810-Q1
The device has three power supply inputs. IN1, which is directly connected to OUT via the power MOSFET, is tied to the VBUS pin in the Type-C receptacle. IN2 also has a current-limiting switch and is multiplexed either to the CC1 or CC2 pin in the Type-C receptacle, depending on cable plug polarity. AUX is the device supply. In most applications, all three supplies are tied together. In a special implementation like power wake, IN1 and IN2 are tied to a single supply, whereas AUX is powered by a supply that is always ON and can be as low as 2.9 V.
USB Specification Revisions 2.0 and 3.1 require VBUS voltage at the connector to be between 4.75 V and 5.5 V. Depending on layout and routing from the supply to the connector, the voltage drop on VBUS must be tightly controlled. Locate the input supply close to the device. For all applications, a 10-μF or greater ceramic bypass capacitor between OUT and GND is recommended, located as close to the Type-C connector of the device as possible for local noise decoupling. The power supply should be rated higher than the current limit setting to avoid voltage droops during overcurrent and short-circuit conditions.