National Semiconductor LM5113 half-bridge gate driver

National Semiconductor has introduced what is claimed to be the first 100 V half-bridge gate driver optimised for use with enhancement-mode gallium-nitride (GaN) power field-effect transistors in high-voltage power converters.

The LM5113 is a highly integrated, high-side and low-side GaN FET driver that reduces component count by 75% and shrinks printed circuit board area by up to 85% compared with discrete driver designs.

Designers of power bricks and communications infrastructure equipment require high power efficiency in the smallest form factor. Enhancement-mode GaN FETs enable new levels of efficiency and power density compared with standard MOSFETs due to their low on-resistance (Rdson) and gate charge (Qg) as well as their ultra-small footprint, but driving them reliably presents new challenges. The driver IC is said to eliminate these challenges, enabling power designers to realise the benefits of GaN FETs in a variety of power topologies.

The device regulates the high side floating bootstrap capacitor voltage at about 5.25 V to optimally drive enhancement-mode GaN power FETs without exceeding the maximum gate-source voltage rating.

The driver also features independent sink and source outputs for flexibility of the turn-on strength with respect to the turn-off strength. A low impedance pull down path of 0.5 Ω provides a fast, reliable turn-off mechanism for the low threshold voltage enhancement-mode GaN power FETs.

The device features an integrated high-side bootstrap diode, further minimising PCB real estate. It also provides independent logic inputs for the high-side and low-side drivers, enabling flexibility for use in a variety of both isolated and non-isolated power supply topologies.