As silicon-based MOSFETs and power devices approach their physical limits, power engineers have turned to gallium nitride (GaN) to increase performance and reduce overall solution size. To achieve smaller form factors and higher efficiency, more and more power supply designers are using GaN-based transistors instead of silicon-based devices. As a wide-bandgap material, gallium nitride has superior properties over silicon: it can operate at higher frequencies, dissipate less power, conduct heat more efficiently and provide better thermal management.
SiC and GaN devices have much higher critical breakdown voltages than Si, allowing thinner drift layers and higher doping concentrations. For a given die area and voltage rating, this results in lower on-resistance, which provides higher efficiency by reducing power losses. In addition, silicon carbide has more than three times the thermal conductivity of silicon, so smaller chips can be used at the same temperature rise. SiC and GaN also offer higher efficiencies than Si by having higher maximum operating temperatures and limiting stress.
In SMPS power supplies, high switching frequency is a major advantage as it reduces the size of magnetics and other components, enabling greater miniaturization and cost savings. However, switching losses are linearly related to frequency. This is why Si-MOSFETs switching at hundreds of hertz have a non-negligible energy loss. Gallium nitride, on the other hand, has higher electron saturation velocity and lower capacitance, providing higher switching rates and lower power losses.
By employing GaN-based switching power transistors, next-generation power applications can operate at higher voltages and switching frequencies, significantly improving performance and reducing losses, footprint and weight compared to traditional silicon-based solutions . These robust inherent properties make GaN an ideal material for mass adoption in evolving applications such as automotive, industrial, telecom and other specific applications in the consumer electronics market, including 100 V clusters and 650 V clusters.
Smart Integrated GaN Solutions
Any electronic device, from home appliances to laptops to data centers, relies on power conversion systems. However, much of today’s power systems are based on a technology that dates back decades, with inefficiencies that take up space that can’t be ignored.
Wise-integration leverages TSMC’s latest certified 650V GaN/Si technology available, capable of managing all industrial processes from device specification to system assembly.
“Our GaN-based product, named WiseGan, integrates a power switch with smart features on the same chip. The power transistors are 650V electronic mode, while smart features include gate control and protection circuits, designer-friendly features and application safety functionality,” said Dominique Bergogne, CTO of Wise-integration.
The WiseGan IC (shown in Figure 1) is suitable for medium power applications in the power range of 30W to 3KW, including:
Consumer Battery Chargers
In-Wall USB-C Charger
Electric Vehicles (E-Bike Chargers)
Industrial (Data Center Power)
WiseGan features an optimized architecture that reduces the size of standard GaN-based chargers by 30%. GaN technology enables extreme performance, and Wise-Integration’s proprietary architecture further improves cost performance by reducing the number of components in AC-DC power converters and enabling efficient solutions without compromising performance.
According to the spokesperson, the main benefits of adopting WiseGan technology are as follows:
Smarter use of resources and improved performance due to ultra-fast switching at high frequencies and reduced active area
Smaller size components provide higher output power and lower power losses
Integrated GaN devices capable of operating at frequencies above 1MHz, enabling higher power densities
Higher energy efficiency (98% vs. 94% of conventional converters)
Thierry Bouchet, CEO of Wise-Integration, said: “Our vision is to maximize the benefits and attractiveness of our customers’ products while reducing energy consumption, size and cost.”
To better meet the demands of the power supply market, the France-based company has combined its WiseGan technology with WiseWare’s patented AC-DC system architecture, which is run by digital controls. WiseWare is a software application that can run on microcontrollers. This dual platform reduces the size, weight and power consumption of the charger by a factor of 6.
As one of the winners of the 2019 national i-Lab competition, funded by the Ministry of Higher Education, Research and Innovation, and supported by the Innovation and Industry Fund, the Wise-Integration research team recently raised €2.7 million. According to the company, the funds will be used to support the industrialization and commercialization of its first-generation WiseGan ICs by 2022 and to further develop its WiseWare power conversion platform.
WiseGan ZVS Evaluation Board
Wise-Integration has also developed an evaluation board that allows evaluation of its WI62100, half bridge 100mΩ (or WI62175 half bridge 175mΩ), enhancement mode high electron mobility transistor (EHEMT), and Si8274GB4D-IS1 gate driver bridge configuration (see Figure 2) .
The board features a ZVS (Zero Voltage Switching) feature that allows soft switching of components, thereby reducing switching losses while enabling high frequency switching. The test board also includes an LTC6907 to generate control signals, headers for power connections, and probe points for waveform measurements.
The WI62100 IC is a half-bridge circuit that integrates two GaN power transistors with RDS(on)=100mΩ in a 6x8mm PQFN package. The LTC6907 oscillator is configured to provide a 1MHz PWM signal to the Si8274GB4D-IS1 isolated gate driver, both powered by 5VDC through the micro-USB power connector. The DT pin of the isolated gate driver corresponds to programmable dead-time control, providing overlap protection to prevent both driver outputs from going high at the same time. So it is used to set the amount of time between one output going low and the other going high. The two driver outputs are connected directly to the gate terminals of the GaN power transistors.