The device uses the internal LDO output and the VCC pin for all internal power supply. The VCC pin draws power either from the VIN (in adjustable output variants) or VOUT/FB (in fixed-output variants). In the fixed-output variants, after the device is active but has yet to regulate, the VCC rail continues to draw power from the input voltage, V_IN, until the VOUT/FB voltage reaches > 3.15 V (or when the device has reached steady-state regulation post the soft start). The VCC rail typically measures 3.3 V in both adjustable and fixed output variants. During start-up, VCC momentarily exceeds the normal operating voltage and then drops to the normal operating voltage.