SLVSD02E March 2015 – August 2021 TPS65982
At power-up, when VIN_3V3 is not present and a dead-battery condition is supported as described in Dead-Battery or No-Battery Support, the TPS65982 will appear as a USB Type-C sink (device) causing a connected USB Type-C source (host) to provide 5 V on VBUS. The TPS65982 will power itself from the 5-V VBUS rail (see Power Management) and execute boot code (see Boot Code). The boot code will observe the BUSPOWERZ voltage, which will fall into one of three voltage ranges: VBPZ_DIS, VBPZ_HV, and VBPZ_EXT (defined in BUSPOWERZ Configuration Characteristics). These three voltage ranges configure how the TPS65982 routes the 5 V present on VBUS to the system in a dead-battery or no-battery scenario.
When the voltage on BUSPOWERZ is in the VBPZ_DIS range (when BUSPOWERZ is tied to LDO_3V3 as in Figure 9-22), this indicates that the TPS65982 will not route the 5 V present on VBUS to the entire system. In this case, the TPS65982 will load SPI-connected flash memory and execute this application code. This configuration will disable both the PP_HV and PP_EXT high voltage switches and only use VBUS to power the TPS65982.
The BUSPOWERZ pin can alternately configure the TPS65982 to power the entire system through the PP_HV internal load switch when the voltage on BUSPOWERZ is in the VBPZ_HV range (when BUSPOWERZ is tied to LDO_1V8D as in Figure 9-23).
The BUSPOWERZ pin can also alternately configure the TPS65982 to power the entire system through the PP_EXT external load switch when the voltage on BUSPOWERZ is in the VBPZ_EXT range (when BUSPOWERZ is tied to GND as in Figure 9-24).