The LMG2640 is a 650V GaN power-FET half bridge intended for switch mode power supply applications. The LMG2640 simplifies design, reduces component count, and reduces board space by integrating half-bridge power FETs, gate drivers, bootstrap diode, and high-side gate-drive level shifter in a 9mm by 7mm QFN package. The low-side current-sense emulation reduces power dissipation compared to the traditional current-sense resistor and allows the low-side thermal pad to be connected to the cooling PCB power ground. The high-side gate-drive signal level shifter eliminates noise and burst-mode power dissipation problems found with external solutions. The smart-switched GaN bootstrap FET has no diode forward-voltage drop, avoids overcharging the high-side supply, and has zero reverse-recovery charge. The LMG2640 supports converter light-load efficiency requirements and burst-mode operation with low quiescent currents and fast start-up times. Protection features include FET turn-on interlock, under-voltage lockout (UVLO), cycle-by-cycle current limit, and over-temperature shut down.