SBVS343A March 2019 – September 2019 TPS7A78
This LDO functional block follows the conventional definition of dropout voltage (VDO) between VLDO_IN and VLDO_OUT. However, the supply mode can have an effect on the dropout voltage.
When the AC input is used as the supply, a fixed dropout (VDO) of 600 mV (typical) between VLDO_IN and VLDO_OUT is maintained for output voltages between 5.0 V and 3.4 V. For output voltages below 3.4 V, the VLDO_IN voltage is maintained at 4.0 V regardless of the output voltage.
A DC supply via the SCIN pin can only be used for output voltages of 3.6 V or less. Under a load condition approaching maximum output current and at high ambient temperature, the LDO can be driven into dropout; see the Switched-Capacitor Stage Output Impedance section for details.