Introduction to TI's GaN-based power solutions and reference designs

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Introduction to TI's GaN-based power solutions and reference designs [Copy link]

TI is a leader in promoting GaN development and supporting system designers in adopting this new technology. TI's GaN-based power solutions and reference designs are committed to helping system designers save space, achieve higher power efficiency and simplify the design process. TI's novel solutions not only optimize performance, but also overcome challenging implementation issues, allowing customers to design energy-efficient systems and build a greener world.

GaN technology and solutions power advantages
GaN provides more efficient and superior power for many reasons. Fast ramp times, low on-resistance, low gate capacitance and output capacitance all reduce switching losses and support operation at multiple frequencies, often an order of magnitude faster than today's silicon-based solutions. This is shown in Figure 1. Lower losses equate to more efficient power distribution, which reduces heat and simplifies practical cooling solutions.

Figure 1. Comparison of device losses for GaN vs. Si
Additionally, high-frequency operation has a positive impact on solution cost because the size, weight, and required materials of necessary magnetic components such as transformers and inductors are reduced.

An application that benefits most from GaN's inherent advantages is switch-mode power supplies.

The goal of an AC/DC power supply is to convert the AC line power to a lower voltage to power or charge low-voltage electrical devices such as mobile phones or personal computers, and this is usually achieved through several power stages. The first stage is the normal power supply, which includes supplying AC line power, which generates a DC bus high voltage, usually 380 V, through a power factor correction (PFC) stage. In the second stage, this voltage is converted to a low voltage (usually 48 V or 12 V) via a high-voltage DC/DC converter. These two stages are called AC-DC conversion stages. They are generally deployed together and provide isolation measures to protect equipment and personnel. The 12 V or 48 V output voltage of the second-stage converter is distributed to the end-use circuits located at different load points (POLs), such as different circuit boards in an equipment cabinet. The third-stage converter has one or more DC converters that can generate the low voltage required by the electronic components.

The example in Figure 2 shows a 1kW GaN-based AC/DC and how GaN improves the power density of the PFC stage, high voltage DC/DC converter, and POL stage. The most important point in this example is not just that GaN is used, but more importantly how it is used. We still use PFC, DC/DC, and POL, but their implementation or the power topology used is different, and the optimized power topology can maximize the performance of GaN.

Figure 2. GaN solutions enable smaller size and higher efficiency in all stages of the power supply.
The PFC stage (Figure 3) uses a high-efficiency totem-pole topology, which enables a unique combination of high power density, high efficiency, and low power consumption that cannot be achieved in similar silicon-based designs. Compared to traditional diode bridge boost PFC using silicon, this stage has an efficiency of over 99% and reduces power consumption by more than 10W.

Figure 3. The GaN PFC topology
high-voltage DC/DC stage uses a highly efficient resonant logic link control (LLC) converter (Figure 4). Although the use of silicon in LLC converters is common, the advantages of GaN are that it increases power density by 50% and increases switching frequency by an order of magnitude. A 1-MHz GaN-based LLC requires a transformer that is one-sixth smaller than the transformer used in a 100-kHz silicon-based LLC design.

Figure 4. The GaN LLC topology
POL stage leverages GaN’s efficient switching properties to enable a 48 V high-efficiency hard-switching converter directly to 1 V. Most silicon solutions require an intermediate fourth stage to convert 48 V to 12 V, but GaN enables true single-stage conversion directly to 1 V. In this way, GaN-based designs can reduce component count by half and increase power density by a factor of three (Figure 5).

Figure 5. Two POL stages to a single stage

Meeting a range of application requirements
GaN's advantages are not limited to AC/DC power supplies.

There are a variety of other applications that can benefit from the higher efficiency and power density that GaN offers, as shown in Figure 6. The end devices mentioned below or some of the more exciting areas are rapidly increasing the utilization of GaN.

Figure 6. Actual and potential GaN application areas

Motors and Motor Control
In motors for robotics and other industrial applications, size and power efficiency are key, but other factors also come into play.

Using GaN solutions, pulse width modulation (PWM) frequencies are increased and switching losses are reduced, which helps drive permanent magnet and brushless DC motors with very low inductance. These characteristics also minimize torque ripple, enabling precise positioning in servo drives and steppers, and supporting high-speed motors with high voltages in applications such as drones.

The narrower width requirements of LiDAR
are quickly making GaN FETs and drivers essential components for LiDAR, which many people more commonly associate with sensing in autonomous vehicles, although it is also used in robotics, drones, security, mapping, and a variety of other fields. Requirements for the next generation of LiDAR include greater range and higher resolution to improve the instrument's capabilities, enabling it to sense farther distances and identify objects more efficiently. GaN's low input and high capacitance enable higher peak output optical power with shorter pulses, which improves imaging resolution while protecting eye safety.

Figure 7. GaN inverter, 100kHz 3-level design

High-performance audio
amplifiers require near-ideal switching waveforms to reduce distortion, because any harmonics of unwanted frequencies will lead to the audible frequency band. GaN solves this problem, it can switch efficiently at much higher slew rates, and the switching behavior is highly predictable, greatly reducing harmonic distortion, achieving more ideal audio performance, and limiting noise to a higher inaudible frequency band.

通过GaN设计更佳解决方案
由于高频电源系统设计带来了新的挑战，即使老练的电源设计师也要经受考验，但如果有现成的解决方案就可以显著缩短设计周期。TI 供应完整的电源级产品，可帮助设计师把问题大大简化。我们现有的解决方案能够满足电源供应链中不同的电压水平和需求，这些解决方案在小巧的低电感封装内集成了内置保护功能。另外，TI的GaN FET驱动器和可以与该驱动器无缝配对的高频模拟与数字控制器，共同有力支持了利用基础元件构建电源系统的设计师。

Figure 8. LMG3410: 600V/70mΩ 12A GaN power stage
The LMG3410 shown in Figure 8 is a single-channel power stage that combines a 70mΩ, 600V GaN FETs and an optimized driver in the same module to minimize parasitic effects that affect high-speed designs through independent components. Built-in features provide temperature, current, and undervoltage lockout (UVLO) fault protection to ensure safe and reliable operation.

For application designers who need efficient operation in a small size, the LMG5200 shown in Figure 9 is a fully integrated half-bridge power stage that provides an 80-V, 10-A solution including half-bridge gate drivers and high-side and low-side GaN FETs. The LMG5200 interfaces directly with analog controllers such as TI's TPS53632G for DC/DC conversion applications and digital controllers such as TI's C2000TM real-time microcontrollers for audio and motor control applications.

Figure 9. LMG5200: 80 V/10 A GaN half-bridge power stage
In simplifying the design process, almost as important as the products themselves is a complete set of development tools. Evaluation modules (EVMs) help designers understand the operation of the solution and make important decisions. Reference designs provide reliable, ready-made circuits that can be used in applications in radar, automotive, uninterruptible power supplies (UPS), motor control, current measurement, and other fields. Our deep support in all areas helps customers design GaN power systems that are as efficient as possible.

GaN today builds on the futureGaN
technology already plays a key role in reducing system size and improving power efficiency. The savings achieved by this technology have a significant impact on all applications, especially data centers, base stations and other high-density systems. In addition, GaN's high-frequency operation facilitates precise motor control and provides higher resolution for LiDAR and audio applications. As innovative topologies and new approaches are invented and applied, other types of applications will quickly follow.

So power system designers no longer have to wait for the GaN revolution to break out. GaN solutions are here today, and TI is committed to and continues to drive innovation in this technology, and we are constantly developing more advanced technologies. Integrated solutions save development time and are ready to use, and our reference designs for a wide range of applications are steadily increasing. As the demand for power efficiency becomes more and more urgent, TI technology and solutions continue to maintain leading innovation to help the world become smarter and greener.