SLVSDF7A December 2016 – July 2017 TPSM84A21
A linear regulator internal to the TPSM84A21 generates a 4.8 V internal supply rail on the VG pin. The input of the linear regulator comes from the VIN pin. The VG supply rail is used to power the internal gate drivers and is the input to another regulator that generates the internal supply rails used by the controller. To improve converter efficiency, an external 5 V supply is recommended to be connected to the VG pin, thereby overriding the internal 4.8 V regulator. This external supply must be between 5.0 V and 5.5 V and must be present before applying input voltage to the VIN pin. If not supplying an external voltage to this pin, leave this pin open.