The UCC12040 is optimized to run with an effective output capacitance of 5 µF to 20 µF. A ceramic capacitor is recommended. Ceramic capacitors have DC-Bias and temperature derating effects, which both have influence the final effective capacitance. Choose the right capacitor carefully in combination with considering its package size, dielectric and voltage rating. It is good design practice to include one 0.1-µF capacitor close to the device for high-frequency noise reduction.