Feb 18, 2022

Premises:

5G networks are cellular networks, where the service area is separated into small geographical areas called cells. In recent years, 5G has stepped into our daily life due to the deployment of the service providers.

With higher-speed, lower latency, and wider spectrum features, a new form of the base station (Micro-Cell) was introduced for 5G application. In this article, we will focus on the 5G structure and Cincon’s new format of power solution.

5G structure concept

While we look at the overview of 5G Ecosystem structure, the end-user device could be various from personnel IOT devices to the public surveillance system. They communicate and transfer data via Fronthaul RAN (Radio Access Network), Backhnaul Edge Computing, and Core Network to the Internet Cloud Server. Among these different levels of communication, the fronthaul RAN plays a crucial role and connect hundreds and thousands of end-user devices for fast exchanging data.

Fig 1. 5G Structure

Main difference from Macro to Small-Cell (Micro) station

To achieve advanced data transferring speed-rate, fronthaul RAN (Radio Access Network) station works at the condition of high-band frequency and millimeter-wave techniques, which affects the structure of base station transforming from Macro to integrated Small-Cell (Micro) station. Unlike Macro station, the coverage area of Small-Cell station is limited due to shorter wavelength and it makes service providers to install more small-cell stations to cover the service area. This change leads designers to shrink down Small-cell size for easier installation around city corners. With limited size of the enclosed case and higher power requirement, conventional types of power supply are not able to meet the needs.

In general, a conventional AC-DC power supply relies on an active fan for heat dissipation, but reliability and airflow become a big headache. For conduction cooling types open frame power supply, the common height would be around 1” to 1.5” (25.4 to 38.1mm) which makes it not possible to fit in certain cases of small cell station. In this case, there is a need of new type power supply requiring to work under the following requirements:

1.Fan-less condition

2.Environmental exposure

3.Low profile

4.High efficiency

5.Good EMI performance

Fig 2. 5G Open-RAN enclosure example

Introduction to New Type AC-DC Brick Power: PDF700S

The PDF700S is a 700 Watts AC-DC full-brick size power module with PFC feature. This series perfectly inherited the advantage of DC-DC brick converter such as great efficiency, encapsulated package, wide operating temperature, and conduction cooling design etc. System designers are no longer limited by the size issue of power supply and they could also add electrolytic capacitors externally with more flexibility. These advantages greatly fit the needs of Small-cell station requirements especially for the height restriction. The PDF700S could be mounted on PCB board with its 0.5 inches low profile. Also, the greater EMI performance meets the requirement in the telecom application.

Application example: PDF700S Evaluation Board (EVB)

The following is the example of PDF700S mounted on EVB board as a reference application. The total height of the board is under two inches, which greatly fits limited size of the enclosed box of small cell station. The module could be attached to the system case or heatsink to be the fanless solution and optimize the heat dissipation performance. System designers could take the design and component layout of EVB and EMI solutions as the reference for their system board design. The EVB could be used to quickly evaluate the performance of the power module as well.

Fig 3. Top view of EVB

Fig 4. Bottom view of EVB

Fig 5. Side view of EVB

Fanless Solution of PDF700S

To achieve the fanless condition in practical application, the following is one example, which simulates the PDF700S280 attached on a 400mm*600mm heatsink as a system case.

Fig 6. Top view of Fan-less Solution

Fig 7. Side view 1 of Fan-less Solution

Fig 8. Side view 2 of Fan-less Solution

After four hours of operation at room temperature(25℃), the hottest spot of the baseplate is under 70 ℃ and stays in heat balance. Under conservative estimation, the derating curve could be referred to the following curve. (Rca ≈1℃/W).

Fig 9. Derating Curve of Fanless Solution

Standard Testing Results of PDF700S280 (Efficiency, Derating curve, EMI performance)

Fig 10. Efficiency Curve @25℃

Fig 11. Thermal Derating Curve with Heatsink M-B012(Rca:2.4℃/W)

Fig 12. PDF700S280 Conducted Report (Class A)

Fig 13. PDF700S280 Radiated Report (Class A)

Cincon Products for 5G solution

Besides the PDF700S AC-DC brick solution, Cincon has multiple types of AC-DC power supplies and DC-DC converters suitable for 5G applications. With the features of baseplate cooling, high efficiency, wide input range, and turn-key solution package etc., designers could find the best power solution for their application. The table below is the reference for you.

Contact Cincon for more information and support: sales@cincon.com.tw