CoolGaN™ Transistor 650 V ≤ G3 for ultimate efficiency and reliability The GS66516B-TR is an enhancement mode GaN-on-Silicon power transistor. The properties of GaN allow for high current, high voltage breakdown and high switching frequency. The GS66516B-MR is a bottom-side cooled transistor in a GaNPX® package with very low junction-to-case thermal resistance for high power applications such as ACDC and DCDC converters, renewable energy, on-board and off-board EV chargers, and industrial power supplies.