SLVSD02D March 2015 – June 2019 TPS65982
The VIN_3V3 input is the main supply to the TPS65982. The VIN_3V3 switch (S1 in Figure 49) is a unidirectional switch from VIN_3V3 to LDO_3V3, not allowing current to flow backwards from LDO_3V3 to VIN_3V3. This switch is on when 3.3 V is available. See Table 18 for the recommended external capacitance on the VIN_3V3 pin.