TI Turns to GaN FETs to Cut Board Space and Boost Power Density in EVsNovember 10, 2020 by Jake Hertz
The new GaN FET family, which includes an integrated gate driver, is said to double power density in onboard chargers and industrial power supplies.
Between efforts for fully electric cars and fully autonomous cars, automobiles are today are integrated with more electrical systems than ever before. With this demand comes the need for electrical engineers to innovate new designs that are both technologically and economically feasible.
Vehicles are becoming increasingly electrified. Image used courtesy of Texas Instruments
From an electrical standpoint, one of the biggest challenges in automobile design is creating systems that are lightweight and compact so vehicle performance isn’t impacted, while also prioritizing durability against high voltages.
The solution that many manufacturers have turned to is gallium nitride (GaN) FETs, a wide bandgap semiconductor that allows power electronics to withstand extremely high voltages.
TI’s New Family of GaN FETs
Texas Instruments is one such company honing in on automotive electrification. This week, the company made headlines with the release of a new family of GaN transistors meant to decrease board space and increase power efficiency in automobile electrical systems.
Simplified block diagram of TI’s new LMG342xR030 GaN FET. Image used courtesy of TI
The new components, namely the LMG3525R030-Q1 and LMG3425R030, are new 650 V and 600 V GaN FETs, respectively. Each of these devices offers different advantages, but both benefit from increased on-device functionality with an integrated 2.2-MHz gate driver.
Uniquely, these chips also offer what is called “ideal-diode mode,” a mode in which the device reduces third-quadrant losses by enabling dead-time control.
What’s Special About These Devices?
By integrating the driver on-chip, the LMG3525R030-Q1 is said to reduce the size of EV onboard chargers and DC-DC converters by as much as 50% compared to existing SiC solutions. The hope here is that saving board space will enable engineers to achieve extended battery range, increased system reliability, and lower design cost. According to TI, this integration can help engineers eliminate more than 10 components typically required for discrete solutions.
In this example, TI explains that ideal diode mode yields 38ns of dead time with 200ns dead time setting. Image used courtesy of TI
TI says the LMG3425R030 uses the integrated gate driver to enable twice the power output, hence doubling the power density compared to silicon MOSFETs. The company also boasts extremely low losses in the device, enabling up to 99% efficiency in AC/DC power delivery applications, according to the press release.
Historically, when designing GaN FETs, engineers are faced with a notable trade-off between switching speed and power losses. These new GaN FETs uniquely avoid this by using what TI calls “ideal diode mode,” which aims to reduce third-quadrant losses by up to 66% compared to discrete GaN and SiC MOSFETs.
An Electric Future
TI hopes its new GaN FETs will bring innovations to the electric vehicle industry. By integrating a driver onboard and offering new functions like the ideal diode mode, the new family of GaN FETs looks to be useful in minimizing board space and saving power, two key considerations for EV design.
Steve Lambouses, vice president for high voltage power at TI, says “Industrial and automotive applications increasingly demand more power in less space, and designers must deliver proven power management systems that operate reliably over the long lifetime of the end equipment."
He continues, "Backed by more than 40 million device reliability hours and more than 5 GWh of power conversion application testing, TI’s GaN technology provides the lifetime reliability engineers require in any market.”