V_C is the bias supply for the DC-DC controller. The MOSFET gate driver runs directly from V_C. V_B is regulated down from V_C, and is the bias voltage for the rest of the converter control. A start-up current source from V_DD1 to V_C is controlled by a comparator with hysteresis to implement a bootstrap start-up of the converter. V_C must be connected to a bias source, such as a converter auxiliary output, during normal operation.

A minimum 0.22-μF capacitor, located adjacent to the V_C pin, must be connected from V_C to RTN to bypass the gate driver. A larger total capacitance is required for start-up.