ZHCSMU0D July 2009 – December 2020 TPS23753A
VC is the bias supply for the DC-DC controller. The MOSFET gate driver runs directly from VC. VB is regulated down from VC, and is the bias voltage for the rest of the converter control. A start-up current source from VDD1 to VC is controlled by a comparator with hysteresis to implement a bootstrap start-up of the converter. VC 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 VC pin, must be connected from VC to RTN to bypass the gate driver. A larger total capacitance is required for start-up.