1 Features

• 650V GaN power-FET half bridge

• 105mΩ low-side and high-side GaN FETs

• Integrated gate drivers with low propagation delays

• Current-sense emulation with high-bandwidth and

high accuracy

• Low-side / high-side gate-drive interlock

• High-side gate-drive signal level shifter

• Smart-switched bootstrap diode function

• High-side start up : < 8μs

• Low-side / high-side cycle-by-cycle over-current

protection

• Over-temperature protection with FLT pin reporting

• AUX idle quiescent current: 250μA

• AUX standby quiescent current: 50μA

• BST idle quiescent current: 65μA

• Maximum supply and input logic pin voltage: 26V

• 9×7mm QFN package with dual thermal pads

2 Applications

• AC/DC adapters and chargers

• AC/DC USB wall outlet power supplies

• AC/DC auxiliary power supplies

• Mobile wall charger design

• USB wall power outlet

3 Description

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 halfbridge

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 overtemperature

shut down.