We all want devices that charge quickly and reliably, while also expecting the chargers themselves to be small, light, and affordable.
To achieve these goals, the consumer electronics industry is turning to gallium nitride (GaN). While switching power supplies have traditionally used silicon for their semiconductor components, GaN provides significantly better power efficiency and thermal management, and enables more compact chargers. According to estimates from STMicroelectronics, using GaN devices in all chargers globally could save 3.5 million tons of CO2 emissions annually.
Power GaN devices are transforming the power electronics industry, with the market expected to exceed $2 billion with a 41% CAGR from 2023 to 2029 – with the consumer market, including fast charging, making up more than $1.3 billion, according to Yole Intelligence.
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The USB-C power standard
At the same time, the consumer charger market is moving to USB Type-C® (also known as USB-C) as the standard for power delivery. USB-C has already become the go-to connector standard, carrying power, video, audio and other data. It is increasingly being used to supply power for smartphones, laptops, and many other devices, including routers, wireless speakers, and wireless headphones.
A standardised USB-C power port is now featured on almost all consumer devices. This is in large part due to the European Union (EU), which now requires most gadgets sold in the EU to charge with USB-C – so long as their power requirements are 100 W or less.
More flexibility with USB Type-C Power Delivery
The original USB-C specification mandated that cables and connectors support a minimum of 60 W, but there has been a growing demand for higher power to enable faster charging.
This has led to various revisions of the specification. The latest version, announced in 2021, is the USB Type-C Power Delivery (USB PD) Revision 3.1. Also called extended power range (EPR), this supports power delivery of up to 240 W.
USB PD also provides intelligent features to optimise power management, including an adjustable voltage supply mode, bi-directional power supply, and flexible system-level control, enabling each device to only take the power it needs for its operation.
GaN and USB-C, the perfect match
GaN technology and the USB-C standard are a perfect match: GaN significantly reduces the size of USB-C chargers while increasing output power, up to 300 W or more, thus enabling fast charging.
GaN-based USB-C external power supplies and chargers are expected to dominate the market over the coming years, offering more compact, higher power output solutions, while setting new industry standards for energy efficiency. Their smaller size also reduces the resources required for production, packaging and recycling, helping to decrease their environmental impact.
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Figure 1: USB PD charger reference design
A study by PECTA showed that the efficiency of silicon-based laptop chargers is typically around 70% to 88% during the charging cycle, while an equivalent GaN-based charger can achieve efficiency of circa 83.5% to 94%. While this is a broad range of figures, the overall trend to lower power losses with GaN chargers than with silicon-based products is clear.
How GaN technology functions in a USB PD charger
For switching power supplies, the typical GaN component used is a high-electron-mobility transistor (HEMT), a type of field effect transistor (FET). This may be used in various topologies, such as active clamp flyback and hybrid flyback, along with controller ICs, drivers and passives.
While GaN’s maximum operational voltage is relatively low at circa 650 V, meaning it is not suitable for high voltage applications, this is more than adequate for consumer power supply use cases, where voltages are much lower.
Let’s look at an example of a recent USB PD charger reference design that uses GaN HEMTs, from Nexperia. This reference design uses the latest power ICs for synchronous rectification (SR), quasi-resonant (QR) flyback converters, and USB Type-C PD (Figure 1 - Click to enlarge image).
The design has excellent efficiency and performance, due to the 650 V e-mode GaN HEMT from Nexperia (Figure 2). Test results demonstrate the reference design achieves efficiency up to 93% at 20V and 3.25A, in compliance with the EU CoC V5 specifications. It also exhibits low standby losses (also in compliance with EU CoC V5) and low EMI, in compliance with EMC Standard EN55022B.
Compared to a best-in-class silicon MOSFET, the GaN HEMT provides multiple advantages:
- Low switching and conduction losses
- Very low reverse recovery losses – there is no body diode
- Increased power density – the charger or adapter can be much more compact
- Increased efficiency – the heatsink size is reduced or eliminated
- Increased switching frequency – passives in the system can be smaller and lower cost
Conclusions
GaN chargers are setting a new benchmark for fast charging with their superior energy efficiency and thermal management capabilities as well as their ability to enable much smaller charger designs.
Figure 2: Test results show high efficiency and low standby losses
With billions of smartphones, laptops and other devices in use worldwide, the impact of moving to GaN is enormous, helping to drive decarbonisation.
Avnet Silica’s power semiconductor portfolio supports the future of power chargers, including the latest GaN devices for consumer applications. Get in touch with our experts to find out how we can help you with your power system design.
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