The world is consuming energy at an unprecedented rate, and the demand for more data and more connected devices will not decline in the foreseeable future. It’s an energy conundrum — how do you accomplish more with less power? Data centers, electric vehicles, consumer electronics, medical equipment and other industrial applications are demanding larger power supplies, but the size, weight, environmental impact and cost of those systems also need to shrink.
Greater power density — defined as the ability to pack more power-delivery capability into smaller volumes — is vital to improving our electronic devices, energy sustainability and digital connectedness, with no compromise in reliability. The best way to efficiently address the challenges surrounding power density is through innovations in semiconductor technology. The opportunity for semiconductors to transform the journey of energy has never been greater.
Addressing power-efficiency needs in server PSUs
Gallium nitride (GaN) is becoming increasingly popular for its ability to enable higher power density and greater efficiency than traditional silicon metal-oxide semiconductor field-effect transistors (MOSFETs) and insulated-gate bipolar transistors (IGBTs). Especially in server and telecom power applications, GaN reduces inductor sizing and improves efficiency in power-factor correction (PFC) and DC/DC converter stages. In recent years, the density of server power-supply units (PSUs) has increased from 40 W/in.3 to over 90 W/in.3 to help meet growing user demand for more power while avoiding increased PSU size. To keep power dissipation manageable in existing PSU volumes, power-circuit efficiency has been a primary focus, with requirements increasing from 93% to >96%. In fact, the European Union is targeting all data center AC power supplies to have >96.5% efficiency by 2023.
Server and data center PSUs have started to adopt GaN and silicon carbide (SiC) FETs to improve the efficiency of their systems. While there is some overlap in the power levels that GaN and SiC serve, GaN has fundamental characteristics that make it a better and longer-term fit for applications in which high power density is critical. GaN-based architectures are capable of working efficiently at much higher switching frequencies, which will enable vastly reduced inductor and magnetic component sizes well into the future. Put differently, the runway for further increases in power density with GaN in these applications is significantly larger than that of any other competing technology.
Complex power topologies enable higher efficiency and power density
To reach higher power levels in ever-smaller form factors while limiting wasted heat dissipation in AC/DC PSUs, designers have adopted advanced structures like bridgeless PFC circuits. A bridgeless PFC topology requires high-frequency switches to have low or no reverse-recovery charge for minimized switching losses; therefore, wide-bandgap devices (SiC or GaN) are necessary in a bridgeless PFC topology. For the isolated DC/DC stage of the PSU, designers are moving from hard- to soft-switching converters to switch at higher switching frequencies for magnetic size reduction and to achieve higher efficiency. In this case, SiC or GaN offers better switching coefficients over silicon devices, which allows for better efficiency at the highest frequency possible. As you can see in the below figure, the change from a traditional bridge PFC rectifier to a bridgeless PFC rectifier reduces the number of diodes and components overall, which contributes to efficiency improvement and size reduction.
Unlocking the full potential of GaN
Newer integrated GaN devices are unique in their ability to allow overcurrent and overtemperature protection, undervoltage lockout and voltage and current sensing, which discrete power switches can’t achieve. Texas Instruments’ GaN FETs with integrated drivers can reach switching speeds of 150 V/ns. These switching speeds, combined with a low-inductance package, reduce losses, enable clean switching and minimize ringing. They also help engineers achieve switching frequencies over 500 kHz, which results in up to 60% smaller magnetics, enhanced performance and lower system costs. When coupled with GaN, real-time control microcontrollers (MCUs) like the TI C2000 family can maximize GaN-based power solutions and deliver benefits such as complex, time-critical processing; precision control; and software and peripheral scalability. Additionally, these MCUs can fully unlock the potential of GaN-based power solutions by supporting different power-design topologies and high switching frequencies to maximize a design’s power efficiency.
As we look to the future, the world’s appetite for energy will continue to increase; technology will need to continue to significantly change and advance along with it. The impact of this evolution will mean increased global demand for innovation and performance excellence in applications like data centers and electric vehicles. Being able to anticipate user needs, adapt to industry trends and swiftly adopt new technologies will be even more important to efficiently and safely advance the journey of energy.
