JAJSH18A March 2019 – September 2019 TPS7A78
The TPS7A78 incorporates two undervoltage lockout (UVLO) circuits; the UVLO_SCIN circuit and the UVLO_LDO_IN circuit. UVLO_SCIN is used to make sure that the active clamp for the bridge has charged the CSCIN capacitor to a voltage level that surpasses the UVLO_SCIN rising threshold to start the switched-capacitor stage. The UVLO_SCIN rising threshold voltage is a function of the LDO output voltage, VLDO_OUT(nom), as indicated in the Electrical Characteristics table.
The UVLO_LDO_IN circuit is used to ensure that the switched-capacitor stage has charged the CLDO_IN capacitor to a voltage level that surpasses the UVLO_LDO_IN rising threshold to enable the LDO circuit to begin regulation at the specified LDO output voltage. See the Startup Behavior section for details.
The LDO_IN pin must not be driven externally and must not be used as a supply rail to an external load.