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Application Note
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With the spread of cloud computing and smartphones and the launch of 5G in 2020, the amount of data that moves on the internet is increasing as high-volume video and game data is added to existing documents, images, and sound data.
In addition, technologies are evolving, exemplified by AI, and a digital transformation (DX) is taking place as a result of the use of big data and the internet of things (IoT). To support these advances, however, large numbers of high-performance servers that can process large volumes of data will be needed. In conjunction with the increased performance of processors and various types of ICs, higher clock speeds of power supply ICs on server boards, high current power saving, miniaturization, noise countermeasures in data lines, and surge countermeasures have become urgent issues. Here, we introduce TDK products for addressing and solving these problems including the VLBU series of ferrite power inductors compatible with the high-efficiency needs of VR13 and VR14 applications, the FS series of DC-DC converters with embedded μPOL™, solutions using the ALT series of pulse transformers and ALC series of common mode filters and chokes, and chip varistors and ceramic transient voltage suppressors used for surge protection.


Power Supply Circuit Blocks and TDK’s Product Lineup

Figure 1. Power Supply Circuit Blocks and TDK’s Product Lineup

Voltage Regulator Modules (VRM) for Driving Processors

The CPU board power supply converts AC voltage to DC voltage using a front-end power supply unit and supplies DC 12V, 5V, and 3.3V to the motherboard. Current CPU operating voltages are 1.5V and lower, and the voltage supplied by the front-end unit is not suitable. Consequently, a voltage regulator module (VRM) is used to convert the DC 12V power to the voltage used by the CPU. CPU power supply voltage has been decreasing year by year in order to achieve low power consumption and high operating speeds (Figure 2 (a)), and as the voltage decreases, the allowable voltage fluctuation value becomes smaller (with a 5% tolerance in output voltage, at 1V the tolerance is 50 mV, but at 0.8V the tolerance is 40 mV), and a VRM is necessary to support fast transient response. If the current exceeds 50A, it is difficult to achieve this with a single DC-DC converter, and a multiphase circuit (Figures 2 (b) and 2 (c)) are used with a high-current VRM.

The conditions for the power inductor used in such a circuit are low inductance, high current, space saving, and low loss, and the VLBU series (Table 1) is suitable.
The VLBU series satisfy the high-efficiency conditions needed for VR13 and VR14 applications.

Figure 2. Core Voltage and Multiphase Circuit
Table 1. The VLBU Series of Ferrite Power Inductors Compatible with the High-Efficiency Conditions needed for VR13 and VR14 Applications and their Features

In addition, TDK provides support for simple layout design using the ultra-compact POL with embedded ICs.
The output voltage and various settings can be programmed at the time of IC shipment according to the use conditions. Please inquire for details.

Figure 3. FS Series of DC-DC Converters with Embedded μPOL™ and its Features

Data Line Circuit Blocks and TDK’s Product Lineup

Figure 4. Data Line Circuit Blocks and TDK’s Product Lineup

Wired LANs are used with cable connections, and Ethernet is currently used as the standard.
Data volumes are growing year by year, and transmission speeds are increasing to 100MbE, 1GbE, and 10GbE. There is also a trend toward mounting multiple pulse transformers on a single board, and there is a need for small sizes. In the current pulse transformer market, toroidal configuration products account for the majority of products, but TDK uses original structural designs to create SMD type products that are compatible with automated mounting. In addition, an automated winding process is used in production, contributing to stable quality.

Figure 5. Solutions Using the ALT Series of Pulse Transformers & ACM Series of Common Mode Filters/Chokes

Surge protection device
Since a wired LAN uses a cable, an ESD failure may occur when connecting or disconnecting the connector, or a surge voltage may be applied to the data line due to a power surge, lightning strike, etc., and the IC may be damaged. As a countermeasure, a protective element is placed for each input / output pin to reduce surge. The chip varistor is smaller than other protective elements and has excellent surge suppression characteristics.

Figure 6. Surge Protection Devices: Chip Varistors and Ceramic Transient Voltage Suppressors