Texas Instruments Serves Up GaN FETs for Smaller Power Converters
As electronics get smaller, TI’s newest GaN chips keep pace by shrinking the size of power electronics such as AC-DC laptop adapters.
Enabling better efficiency for low-power fast-charging applications, Texas Instruments recently announced three new members of its GaN portfolio that offer smaller overall footprints. As designers work to improve the power handling capabilities of AC-DC converters, low-power GaN technology offers smaller and lighter solutions that improve the thermal performance of the converters.
TI’s latest GaN chips allow designers to shrink the size of power converters while maintaining efficiency and improving thermal performance.
Compared to silicon, GaN exhibits many characteristics such as a wider bandgap that makes it ideal for power electronics applications. As a result, many organizations have worked to create smaller and more efficient GaN FETs for designers to use.
This article takes a closer look at the new GaN FETs from TI and puts the improved specs in context in an example power conversion application. In addition, we will discuss the broader trend toward GaN technology to find out how the material could spell out better efficiency and smaller power devices.
A major benefit of GaN compared to silicon is the higher reverse voltage tolerance combined with the improved on-resistance, making it ideal for switching power supplies that rely heavily on low resistance switches. In addition, GaN exhibits a faster switching time compared to silicon, minimizing energy losses while the transistor is turning on or off. TI explores these issues in its technical article about the benefits of lower low-power GaN technology.
In addition to the GaN FET, each LMG362x device includes gate drivers and current-sense emulation, allowing for improved performance with less power loss and fewer components.
Each new member of TI’s GaN product line, the LMG3622, LMG3624, and LMG3626, offer 650 V reverse voltage tolerance, allowing designers to increase the maximum voltages that may be handled in small power converters. In addition, the on-resistance for each GaN FET ranges from 270 mΩ down to 120 mΩ for the LMG3622, allowing designers to find the optimal tradeoff between price and efficiency for their specific applications.
In addition to the benefits afforded by the GaN FETs inside the ICs, each chip also includes several key blocks that simplify the development process with the LMG362x series. Primarily, the internal gate driver allows the chips to be used with industry standard controllers, ensuring that turning on and off the GaN FET is as simple as possible.
In addition to the gate driver, each IC is also equipped with current sense emulation to allow designers to monitor the output current of the GaN FET in a power efficient manner. While other GaN ICs may require output current measurement directly using a shunt resistor, the LMG362x series uses a scaled replica of the output current to reduce power consumption and remove the need for large passive components. Check out the LMG3622 datasheet for more information on this.
Current-sense emulation allows designers to reduce the power consumption of external shunt resistors, improving thermal performance for small power converters.
The peripherals included in the TI GaN ICs ultimately allow designers to reduce the size of their power converters by reducing the number of passive components and integrating more functionality on-chip. The LMG362x series is available now in both production and pre-production quantities.
Maximizing Efficiency with GaN
While GaN likely won’t replace silicon anytime soon, the efficiency benefits afforded by the material have allowed designers to reduce the size of their devices while simultaneously improving their performance. With the release of the LMG362x lineup of GaN FETs, this momentum may continue as designers are provided with more tools and resources.
As more devices begin to include the LMG362x series of GaN FETs, it will be exciting to see how power electronics adapt to the potential for smaller footprints. Regardless, increasing the number of GaN-powered electronics is certainly a benefit for designers and consumers alike, and has the potential to shift the way that electronics are powered.
All images courtesy of Texas Instruments