Both GaN and silicon carbide (SiC) are transforming PSU designs by offering higher efficiency when compared to traditional silicon (Si) devices. GaN offers even lower reductions in switching energy losses than SiC, and GaN is appropriate for high switching frequencies.

Figure 4-1 compares Texas Instruments' (TI) GaN technology with industry leading SiC and super-junction Si devices. The comparison demonstrates that GaN from TI achieves substantially lower switching energy losses and enables higher operating frequencies [see reference 6].

Figure 4-1 Switching Energy Losses Comparison

This efficiency improvement is proven in the transition conduction mode (TCM) totem pole PFC reference design (PMP40988 in Figure 4-2), which leverages the zero-voltage detection (ZVD) function of the LMG3526 GaN device, and another design (PMP23475), which utilizes zero-current detection (ZCD). Both of these designs have achieved a peak efficiency of higher than 99.0% [see references 8 and 10].

Figure 4-2 Efficiency of PMP40988

Figure 4-3 PMP40988 TCM Totem Pole PFC With ZVD GaN