SLUSDB2A August 2018 – December 2021 UCC28951
Operate the UCC28951 controller from a VDD rail within the limits given in the Section 6.3 section of this data sheet. To avoid the possibility that the controller might stop switching, do not allow the VDD to fall into the UVLO_FTH range. To minimize power dissipation in the controller, ensure that VDD is not unnecessarily high. Maintaining VDD at 12 V is a good compromise between these competing constraints. The gate drive outputs from the controller deliver large-current pulses into their loads. This indicates the need for a low-ESR decoupling capacitor to be connected as directly as possible between the VDD and GND terminals.
TI recommends ceramic capacitors with stable dielectric characteristics over temperature, such as X7R. Avoid capacitors which have a large drop in capacitance with applied DC voltage bias. For example, use a component that has a low-voltage co-efficient of capacitance. The recommended decoupling capacitance is 1 μF, X7R, with at least a 25-V rating with a 0.1-µF NPO capacitor in parallel.