National Semiconductor Introduces Industry’s First 100V Half-bridge Gate Driver for Enhancement-mode Gallium-Nitride Power FETs

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 to standard metal-oxide semiconductor field-effect transistors (MOSFETs) due to their low on-resistance (Rdson) and gate charge (Qg) as well as their ultra-small footprint, but driving them reliably presents significant new challenges. National’s LM5113 driver integrated circuit (IC) eliminates these challenges, enabling power designers to realize the benefits of GaN FETs in a variety of popular power topologies.
Meeting the stringent gate drive requirements of enhancement-mode GaN FETs requires multiple discrete devices and significant circuit and PCB design effort. National’s LM5113 fully-integrated enhancement-mode GaN FET driver greatly reduces circuit and PCB design effort and delivers industry-best power density and efficiency.
“National’s LM5113 bridge driver helps designers unleash the performance of eGaN® FETs by simplifying the design,” said Alex Lidow, co-founder and CEO for Efficient Power Conversion Corporation. “The LM5113 dramatically reduces component count, and paired with our eGaN FETs, enables a tremendous PCB area savings and higher level of power density versus equivalent MOSFET-based designs.”
Technical Features of the LM5113 Bridge Driver.
National’s LM5113 is a 100V bridge driver for enhancement-mode GaN FETs. Using proprietary technology, the device regulates the high side floating bootstrap capacitor voltage at approximately 5.25V to optimally drive enhancement-mode GaN power FETs without exceeding the maximum gate-source voltage rating. The LM5113 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 Ohms provides a fast, reliable turn-off mechanism for the low threshold voltage enhancement-mode GaN power FETs, helping maximize efficiency in high frequency power supply designs. The LM5113 features an integrated high-side bootstrap diode, further minimizing PCB real estate. The LM5113 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.