8.3.3.3 Power up REGN Regulator (LDO)
The REGN LDO supplies internal bias circuits as well as the HSFET and LSFET gate drive. The LDO also provides bias rail to TS external resistors. The pull-up rail of /PG can be connected to REGN as well. The REGN is enabled when all the below conditions are valid.
- VBUS above VVBUS_UVLOZ in boost mode or VBUS below VVBUS_UVLOZ in buck mode
- Poor Source Qualification detects a valid input source
- Input Source Type Detection completes and sets appropriate input current limit
- After 220 ms delay is complete
If one of the above conditions is not valid, the device is in high impedance mode (HIZ) with REGN LDO off. The device draws less than IVBUS_HIZ from VBUS during HIZ state. The battery powers up the system when the device is in HIZ.