The UCC3895 device should be operated from a VDD rail within the limits given in the Recommended Operating Conditions of this data sheet. To avoid the possibility that the device might stop switching, VDD must not be allowed to fall into the UVLO(off) range. In order to minimize power dissipation in the device, VDD should not be unnecessarily high. Keeping VDD at 12 V is a good compromise between these competing constraints. The gate drive outputs from the UCC3895 device 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 PGND 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 part 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.