The LMG3626 is an integrated 650-V 270-mΩ GaN power FET intended for use in switching-power converters. The LMG3626 combines the GaN FET, gate driver, current-sense emulation function, and protection features in a 8-mm by 5.3-mm QFN package.

The 650-V rated GaN FET supports the high voltages encountered in off-line power switching applications. The GaN FET low output-capacitive charge reduces both the time and energy needed for power converter switching and is the key characteristic needed to create small, efficient power converters.

The LMG3626 internal gate driver regulates the drive voltage for optimum GaN FET on-resistance. The internal driver reduces total gate inductance and GaN FET common-source inductance for improved switching performance, including common-mode transient immunity (CMTI). The GaN FET turn-on slew rate can be individually programmed to one of four discrete settings for design flexibility with respect to power loss, switching-induced ringing, and EMI.

Current-sense emulation places a scaled replica of the GaN FET drain current on the output of the CS pin. The CS pin is terminated with a resistor to AGND to create the current-sense input signal to the external power supply controller. This CS pin resistor replaces the traditional current-sense resistor, placed in series with the GaN FET source, at significant power and space savings. Furthermore, with no current-sense resistor in series with the GaN FET source, the GaN FET thermal pad can be connected directly to the PCB power ground. This thermal pad connection both improves system thermal performance and provides additional device routing flexibility since full device current can be conducted through the thermal pad.

The AUX input supply wide voltage range is compatible with the corresponding wide range supply rail created by power supply controllers. Low AUX quiescent currents support converter burst-mode operation critical for meeting government light-load efficiency mandates. Further AUX quiescent current reduction is obtained by placing the device in standby mode with the EN pin.

The IN and EN control pins have high input impedance, low input threshold voltage and maximum input voltage equal to the AUX voltage. This allows the pins to support both low voltage and high voltage input signals and be driven with low-power outputs.

The LMG3626 protection features are under-voltage lockout (UVLO), cycle-by-cycle current limit, and overtemperature protection. The overtemperature protection is reported on the open drain FLT output.