8.1 Application Information

To operate GaN transistors at very high switching frequencies and to reduce associated switching losses, a powerful gate driver is employed between the PWM output of controller and the gates of the GaN transistor. Also, gate drivers are indispensable when the outputs of the PWM controller do not meet the voltage or current levels needed to directly drive the gates of the switching devices. With the advent of digital power, this situation is often encountered because the PWM signal from the digital controller is often a 3.3 V logic signal, which cannot effectively turn on a power switch. A level-shift circuit is needed to boost the 3.3 V signal to the gate-drive voltage (such as 5 V) in order to fully turn on the power device and minimize conduction losses.

Gate drivers effectively provide the buffer-drive functions. Gate drivers also address other needs such as minimizing the effect of high-frequency switching noise (by placing the high-current driver IC physically close to the power switch), reducing power dissipation and thermal stress in controllers by moving gate charge power losses from the controller into the driver.

The LMG1020 is a 60-MHz low-side gate driver for enhancement mode GaN FETs and Si FETs in a single-ended configuration. The split-gate outputs with strong source and sink capability provides flexibility to adjust the turnon and turnoff strength independently. As a low side driver, LMG1020 can be used in a variety of applications, including different power converters, LiDAR, time-of-flight laser drivers, class-E wireless chargers, synchronous rectifiers, and augmented reality. LMG1020 can also be used as a high frequency low current laser diode driver, or as a signal buffer with very fast rise/fall time.