SLVSD02D March 2015 – June 2019 TPS65982
The TPS65982 Power Management block receives power and generates voltages to provide power to the TPS65982 internal circuitry. These generated power rails are LDO_3V3, LDO_1V8A, and LDO_1V8D. LDO_3V3 is also a low power output to load flash memory. VOUT_3V3 is a low power output that does not power internal circuitry that is controlled by application code and can be used to power other ICs in some applications. The power supply path is shown in Figure 49.
The TPS65982 is powered from either VIN_3V3 or VBUS. The normal power supply input is VIN_3V3. In this mode, current flows from VIN_3V3 to LDO_3V3 to power the core 3.3 V circuitry and the 3.3 V I/Os. A second LDO steps the voltage down from LDO_3V3 to LDO_1V8D and LDO_1V8A to power the 1.8 V core digital circuitry and 1.8 V analog circuits. When VIN_3V3 power is unavailable and power is available on the VBUS, the TPS65982 will be powered from VBUS. In this mode, the voltage on VBUS is stepped down through an LDO to LDO_3V3. Switch S1 in Figure 49 is unidirectional and no current will flow from LDO_3V3 to VIN_3V3 or VOUT_3V3. When VIN_3V3 is unavailable, this is an indicator that there is a dead-battery or no-battery condition.