SLUSF25 September 2025 UCC27834
PRODMIX
The power losses of the UCC278X4 (PUCC278X4) are estimated by calculating losses from several components.The combined power losses due to quiescent current (IQDD, IQBS) and no-load switching are calculated below:
Refer to Figure 5-16 to find IVDD and IVHB.
Dynamic losses incurred due to the gate charge while driving the FETs Q1 and Q2 are calculated below. Please note that this component typically dominates over the dynamic losses related to the internal VDD and VHB switching logic circuitry in the UCC278X4.
The dynamic losses are shared between the internal pullup and pulldown resistance of the gate driver IC, the external gate resistance, and the internal gate resistance of the switching device. The pullup resistance changes dynamically during switching, so using ROH provides for an overestimate of the gate driver power dissipation, which provides for design margin.
The total power losses in the gate driver IC for this example are calculated below: