When EN is driven high, the TPS7H3302 VTT regulator begins normal operation. When EN is driven low, VTT discharges to GND through an internal 18-Ω (typical) MOSFET. VTTREF remains on when EN is driven low. EN is not tied high internally to prevent power sequencing issues with an external signal that may be controlling the enable. EN is a floating input and not internally tied, thus the user can have complete control over where and when the EN signal is generated. EN feeds directly into power-good (PGOOD). When enable is low, PGOOD is low.