Network Transformer: How to use “small” changes to play a big market?

[Introduction]With the advantages of excellent performance, simple connection, and perfect ecology, Ethernet has become a common communication protocol standard in the local area network (LAN) field, and it has continued to evolve rapidly with the rapid growth of data consumption.

The development trend of Ethernet today is reflected in three aspects:

● Performance is getting higher and higher: 10/100Gbps Ethernet has become the mainstream technology, and 400Gbps technology is also coming. When it comes to increasing transmission rates, Ethernet has never slowed down.

● Wider and wider application: In addition to the field of data communication, Ethernet is also entering the fields of industrial automation control and in-vehicle network that have strict requirements on real-time and determinism. Technologies such as TSN (Time Sensitive Networking) are working hard to adapt Ethernet to the requirements of these new scenarios, and a single Ethernet architecture is becoming a reality.

● The functions are becoming more and more diverse: In addition to transmitting data, Ethernet can also undertake the responsibility of power transmission on the same medium through Power over Ethernet (PoE) technology, which makes the deployment of Ethernet terminal equipment easier and makes Ethernet The tentacles can extend to more places.

It is not difficult to judge that the above three trends determine that for a long period of time in the future, the growth of Ethernet ports will maintain a considerable acceleration, and the demand for related components will continue to rise. This article will focus on one of these materials – which may seem less eye-catching in the BOM, but is indispensable in every Ethernet connection port – it is the network transformer (also known as “” LAN Transformer”).

The role of the LAN transformer

The LAN transformer is a magnetic module, which is usually used as the interface connecting the physical layer (PHY) transceiver and the RJ45 connector, and mainly plays the role of signal conditioning and isolation to achieve higher signal quality and ensure more reliable network connections.

Specifically, the working principle of the LAN transformer is the same as that of the transformer we are familiar with. It couples the differential signal transmitted by the PHY to the other end of the connecting network cable through the conversion of the electromagnetic field. In this seemingly “simple” process, the LAN transformer plays a very important role:

● By coupling and filtering the differential signal from the PHY with differential mode coupled coil coupling, the LAN transformer can enhance the signal and support longer transmission distances.

● Usually, the levels of the devices on both sides of the Ethernet port are inconsistent. If they are directly connected, a large current may flow from a device with a high potential to a device with a low potential, causing damage to the device. Transient energy changes—such as electromagnetic induction and static electricity—are also conducted to other equipment, which can easily damage sensitive devices such as chips. The LAN transformer can play a role in isolation and improve the overall stability and reliability of the system.

● When the common mode signal passes through the isolation transformer, since the voltage polarities at both ends of the coil are the same, no current will be formed, and the common mode signal will not be transmitted to the secondary coil, so the LAN transformer can suppress the common mode interference . For the common mode noise transmitted to the secondary through the coupling capacitor path between the coils, the common mode choke coil can be used in conjunction with the LAN transformer to suppress and improve the quality of the signal. Therefore, LAN transformers can also play an important role in suppressing EMI interference and optimizing the network transmission environment.

Network Transformer: How to use “small” changes to play a big market?

Figure 1: Typical application of a LAN transformer

(Image source: Bourns)

Shortcomings of LAN Transformers

Traditional LAN transformers usually consist of two parts, a pulse transformer (T1) and a common mode choke (T2). These ferrite cores wrapped with enameled wires are integrated into a plastic case with terminal pins to form a complete module.

Figure 2: Traditional LAN Transformer Module

(Image source: Bourns)

Careful friends may have found that traditional LAN transformers use toroidal ferrite cores (T-shaped cores). This core is chosen because its symmetrical closed-loop structure can minimize the leakage of magnetic flux, so it has higher efficiency and less radiated EMI, and the performance advantage is obvious.

However, everything has advantages and disadvantages. Although the traditional LAN transformer with T-shaped magnetic core has good performance, it will inevitably use a lot of labor in the winding process during manufacturing, which cannot realize automatic production. On the one hand, this is not conducive to improving production efficiency and reducing production costs. On the other hand, manual winding is also difficult to ensure the consistency of the electrical performance of the product, resulting in the “non-uniformity” in the transmission quality of traditional LAN transformers. In addition, since the traditional LAN transformer is a module that encapsulates two magnetic components, a transformer and a common mode choke coil, the components are larger in size and require higher PCB design.

The shortcomings of these traditional LAN transformers may have been “ignored” in the past, but with the rapid increase in the number of Ethernet ports, in addition to performance, developers have other factors such as cost, delivery time, component size and ease of use. It is bound to have higher demands, so it is imperative to make up for the shortcomings of traditional LAN transformers and develop an alternative solution.

Advantages of Chip LAN Transformers

An alternative that can meet the new requirements of the new trend is the chip transformer.

Figure 3: Chip LAN Transformer

(Image source: Bourns)

Compared with the traditional LAN transformer with toroidal core and integrated package of multiple magnetic components, the changes of chip LAN transformers are mainly reflected in two aspects:

● First, the magnetic structure adopted by the chip LAN transformer is: firstly, the coil is wound on the drum-shaped magnetic core, and then the closed magnetic circuit of the ring-shaped magnetic core is “simulated” by covering the ferrite plate, so as to achieve the same performance as the traditional LAN. Transformer par performance. Excellent EMI suppression can also be achieved if used with a chip common mode choke (common mode Inductor).

● Second, the chip LAN transformer is a center-tapped discrete magnetic component, which makes its shape thinner and lighter. Compared with the traditional integrated module solution, it can bring greater flexibility to PCB layout.

Another significant advantage of this architectural design change is that it enables the use of automated advanced technology in the winding process, which is based on fully automated production of surface mount magnetic components to a large extent overcome. The shortcomings of traditional LAN transformers requiring manual production and low product stability have greatly improved product quality and consistency, shortened the delivery cycle, and provided convenience for subsequent large-scale automated SMT assembly.

Figure 4: Performance comparison of conventional and chip LAN transformers (modules)

(Image source: Bourns)

Bourns Chip LAN Transformer Solution

It is precisely because the chip LAN transformer has outstanding advantages in practical application and reliability, and also achieves high performance, it has been a star product in the field of magnetic components in recent years. The two series of shielded Gigabit Ethernet chip LAN transformers recently launched by Bourns can be described as “stars among stars”.

The two chip LAN transformers, including the SM453230-121N7YP and SM453230-231N7YP series, are compact and flexible discrete solutions.

Figure 5: SM453230-x1N7YP Chip LAN Transformer

(Image source: Bourns)

Among them, SM453230-231N7YP supports 1/2.5/5Gb Ethernet, while SM453230-121N7YP can support 10Gb network. At the same time, this product can provide 1500VAC / 60s high voltage isolation and withstand up to 2400V, 1.2/50μs pulse voltage shock, supports a wide temperature range of -40°C to +85°C, so it is very suitable for high-speed telecom and network equipment products .

It is worth mentioning that the SM453230-x1N7YP chip LAN transformer can also support the PoE+ Power over Ethernet standard and can provide a current of 700mA. You must know that if you want to have the current capacity specified by PoE+ and the withstand capacity of DC bias current, you need to solve the problems of coil heating and core saturation. Obviously, Bourns’ solution has good countermeasures in these aspects.

Figure 6: Block Diagram of SM453230-x1N7YP Chip LAN Transformer

(Image source: Bourns)

In terms of EMI suppression, the SM453230-x1N7YP chip LAN transformer provides users with two options: Users can use Bourns-recommended chip common mode chokes (see Figure 7) to reduce EMI interference; even without additional common mode Filters, center taps can also achieve good common mode rejection to simplify the developer’s work in EMC design.

Figure 7: Comparison of characteristics of SM453230-121N7YP and SM453230-231N7YP chip LAN transformers (Image source: Bourns)

Table 1: SM453230-x1N7YP Chip LAN Transformer Specifications

(Source: Bourns)

Summary of this article

Finally, to sum up: Ethernet, as the backbone of today’s digital age, is developing rapidly and unstoppably with the continuous increase in data consumption. The resulting new demands are transmitted to the tiny magnetic component of the LAN transformer, which will also It poses no small challenges in terms of manufacturability, quality consistency, cost, and delivery.

The transformation from traditional LAN transformers to chip LAN transformers can well meet the requirements of the development trend of Ethernet, and use a seemingly “minor” change to play a market that is still expanding and huge.

The Links:   SKIIP 02NAC066V3 G190EAN013