Global telecommunications network
Today, we all depend on telecommunication networks for communication and data transfer. And these critical systems rely on servers that require adequate and reliable power. Therefore, power supply units (PSUs) are effectively the heartbeat that enable server systems to function. As server systems have grown in complexity, demands on PSUs have caused many manufacturers to look for alternatives to silicon-based power supply components to increase power supply capacity and efficiency.
Gallium-nitride (GaN) has emerged as a promising solution, especially for power factor correction (PFC) designs, providing size, efficiency and cost advantages over silicon-based solutions. As a result, many PSU manufacturers have started taking advantage of discrete GaN FETs in their designs. However, Texas Instruments’ integrated approach to GaN technology offers additional advantages for telecom and server PSUs.
Understanding Server Power Supply Unit Design
Server systems are typically powered from the grid by an AC/DC power supply. The importance of data communication system efficiency has resulted from the need to do more with less power. Global standards have been put into place to help guarantee efficiency in the AC input stage of PSUs. To help facilitate compliance, many governments mandate that PSUs have a PFC stage. Most manufacturers design and build their systems to meet the 80 Plus Titanium efficiency levels, shown below.
| 80 Plus Titanium Efficiency Levels for Certification | |||
| Rated load percentage (%) | 230 V Internal Redundant | 230 V EU Internal Non-Redundant | 115 V Internal Non-Redundant |
| 10 | 90% | 90% | 90% |
| 20 | 94% | 94% | 92% |
| 50 | 96% | 96% | 94% |
| 100 | 91% | 94% | 90% |
The above levels are used for power supplies in computing and networking architectures for all environments. In addition, data centers and service stations typically adhere to the 230 V internal redundant levels.
Advantage of GaN Technology for PSU Power Factor Correction
There are several popular PFC designs that are implemented for PSUs, including the ones below.
PSU PFC switch architectures
Of the three designs above, both the AC-switch and active bridge PFCs require more switches than the totem-pole architecture. Consequently, the totem-pole alternative has less power loss and fewer components, which results in greater efficiency and lower costs.
In order to fully take advantage of the totem-pole PFC architecture, it is necessary to consider the FET switches. MOSFETs have a high reverse recovery due to a body diode, which causes high power loss as well as potential damage from shoot-through. On the other hand, silicon-carbide (SIC) MOSFETs have a lower reverse recovery, which lowers power loss and risk. However, GaN technology enables zero reverse-recovery, which makes significantly lower power loss possible.
TI’s Integrated GaN Solution
Implementing GaN technology in a totem-pole configuration results in higher PSU efficiency for telecommunications servers. Many manufacturers use discrete GaN FETs or integrated GaN devices to power high-efficiency PSUs for a wide range of applications, including telecommunications servers.
TI’s integrated GaN solution offers significant advantages over discrete approaches. TI’s integrated GaN FETs include a gate driver as well as sensing and protection features in a single package, shown below, eliminating the additional power losses from external drivers as well as reducing the size of the power supply and increasing switching speeds.
TI LMG3422R030: Integrated GaN technology FET design
Advantages of TI’s integrated GaN Technology PFC Design for Server PSUs
- No reverse recovery
- Minimizes power loss
- 150 V/ns gate switching speed achievable
- Integrates reporting and protection in a single package
- Reduces the number of components and design complexity
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