Although segregation is crucial, but its design is extremely complex also. When control power and data signal pass segregation bar, meeting generation electromagnetism is disturbed (EMI) . These radiate blast off (RE) the meeting function generation to other electron system and network is negative influence.

 

To taking the circuit design of segregation, an important step is to cross segregation bar to transmit power, alleviate the RE of generation. Although traditional method is possible effective, but often need balance to accept or reject, include possibly to use schism type circuit and transformer to transmit power among them. Ponderosity of this kind of method is time-consuming, can take up valuable PCB space, without won’t raise cost. More the solution with efficient economy is the circuit that wants transformer and place compositive in smaller appearance, if chip is enclosed.

 

Although can save circuit board space so, reduce the complexity of the design and cost, but also make transformer bulk decrescent, had winding is fewer, the switch frequency with taller need (be as high as 200MHz) ability transmits needs power efficiently sub end. Below more high frequency rate, parasitism in all model (CM) the winding that electric current may pass transformer from primary end with allowing sexual kind coupling comes sub end. Because keep apart the nature place of bar to be restricted, without physics method can let these CM electric current return primary end. Segregation bar forms occasionally extremely, aux will be able to measures the formal radiate with CM electric current, let its return primary end. This caused element of another serious consideration: Add up to compasses sex.

 

Electromagnetism compatibility (EMC) requirement

 

Before the product appears on the market, must accord with EMC regulation. The circuit that wants transformer and place is compositive produce EMI to the smaller conference in enclosing, because this needs to use complex and the RE with high cost restrains a technology, in order to satisfy electromagnetism compatibility (EMC) the requirement of code.

 

EMC is subsystem pointing to report work normally in its target environment and noninterference is other systematic ability. Different area has the whole world EMC code, fall to be able to work normally with the case that has other product presence at ensuring all products are in. Radiation emissive quantity must use the formulary level of environment and correspondence of applied circumstance place under the target. Accordingly, it is important that EMC checks a of the process to already became a product to appear on the market with attestation component. The product that sells in the European Union needs to have CE sign, and the product that sells in the United States needs to obtain FCC to classify attestation. To obtain these attestation, need carries out an EMC test to the system. In industry, medical treatment, communication and consumptive environment, radiation blasts off to must accord with CISPR 11/EN55011, CISPR22/EN 55022 or FCC Part15 standard normally.

 

Graph 1: Launch the give a demonstration that measures heighten

 

CISRP 11/EN 55011

 

This standard is applied to for industry, science and medical treatment (ISM) purpose and the produces radio frequency energy equipment of the design. Inside standard limits, equipment may be divided it is two groups. The 2nd group is included be generated of purpose and the equipment of all ISM RF in energy of local use radio frequency. The 1st group includes all facility that the 2nd group does not belong to inside this standard limits.

 

CISRP 22/EN 55022

 

The IT equipment that this standard applies to contented and undermentioned condition (ITE) : Main function is input, memory, show, retrieve, transmit, processing, exchange or control data and telegraphic news union rise, the likelihood deploys port of one or more terminal, use at transmitting information normally.

 

Below each standards, equipment is classified further, every category needs to abide by a group to discharge limitation alone:

 

● A kind: Use in the equipment with industrial application and uptown blame

● B kind: With the equipment in residential environment

 

As a result of B kind what limitation enclothes is the residence (or light industry) environment, and the product in this kind of environment is more possible each other are very adjacent (inside 10 meters of limits of broadcast and TV receiver) , because this is more strict (than A kind of low 10dB) , lest pose interference problem.

 

Graph 2 showed the A related to CISPR11/EN55011 and CISPR22/EN55022 kind with B kind limitative line. Inside this frequency limits, accord with CISPR22/EN55022B kind the standard is meant also accord with CISPR11/EN55011B kind standard.

 

Graph 2: Radiation launchs standard — to limit a line

 

In the design cycle considers EMC at the beginning

 

According to the report, the product of 50% first EMC test ends with failing. Because lack relevant knowledge,this may be, and fail to design a technology in the inchoate application EMC of products plan phase. Before if be in,functional design is finished all the time oversight EMC problem, can bring bad news to expend time normally and the challenge with high price. In addition, develop the ceaseless development of the process as the product, can use the technology that solves EMC problem less and less also, because of product side change be sure to bring about plan overtime and cost to increase.

 

Want utmost ground to shorten design time and reduce project cost, undertake in the project EMC design is crucial in the begining. It is very important also to choose and be placed of package. Bring into the parts of an apparatus that accords with occupation standard choice and design to be able to rise add up to compasses sex.

 

EMC restrains a technology: Earnestly needs better method

 

The traditional method photograph with transformer of use schism type is compared, mix transformer circuit is compositive to chip class package amount can reduce in enclosing, save PCB space greatly then, but may introduce taller radiate to blast off. Radiation blasts off restrain a technology to be able to make the design of PCB more complex, or need additional package, the cost that because this may offset,compositive transformer saves and space.

 

For example, a kind of when restrain radiation to blast off in PCB level common method is to be CM electric current to form a low impedance way that from sub Duan Zhichu class carries, reduce RE level thereby. Should come true this, bypass electric capacity can be used between primary end and sub end. This bypass capacitance can be schism style electric capacity, also can be embedded interlining capacitance.

 

Schism style electric capacity is the simplest solution, the likelihood is to have down-lead or exterior installation package. It still has the advantage that applies to 2 PCB, but price of schism style electric capacity is high and volume is huge, can take up valuable PCB space, be in especially likelihood pile by the segregation bar of many component.

 

Another is not very good solution it is to use embedded bypass capacitance, can form this capacitance when the two faces coincide in PCB (graph 3) . This kind of capacitance has a few very useful character, the inductance that the reason depends on making the same score andante capacitance is extremely low, because this is effective inside bigger frequency range. It can improve emissive performance, but because need to define a layer oneself thick will acquire right electric capacity, and PCB needs 4 or more layer, so design complexity and cost are met heighten. In addition, return the kind that must carry segregation, the lowest that ensures interior overlaps the span of the layer satisfies place of relevant segregation standard to set is apart from a standard.

 

Graph 3: The capacitance of in-house PCB bypass that forms between central power source and ground connection layer

 

Bypass capacitance still allows to communicate leak and twinkling to change cross segregation bar to receive layer coupling to receive layer to another from. Although bypass capacitance is general very small, but twinkling of high-pressured high speed changes can cross segregation bar infuse through this capacitance a large number of electric current. If application needs to bear,abominable electromagnetism twinkling changes, like electrostatic discharge, report fast twinkling changes and surge, also must consider this.

 

No matter be minute of vertical,still be embedded, use bypass capacitance is not ideal restrain a technology. Although it can be helped reduce radiation to blast off, in order to raise package, use complex PCB layout and raise transient state sensitivity to be cost. Ideal inhibition the technology does not need to use bypass electric capacity, because this can reduce cost and the complexity that PCB designs.

 

Discharge use complex those who restrain a technology is necessary

 

Below good case, component of compositive segregation power source should include the measure that drops chip radiate to blast off, need not be in exterior and additional add complex measure, can ensure through systematic level radiation launchs a test. Come so, need to lay package 2 layer board to go up only, can launch a test through severe radiation, and need not make circuit board for many times.

 

Low radiation launchs isolator

 

Products of next generation IsoPower® series use the design technology of innovation, can avoid to produce a large number of radiate to blast off, go up in the 2 layer board that do not have bypass capacitance even not exceptional also. ADuM5020 and ADuM5028 are measuring contented CISPR22/EN55022B with making rich considerably kind limitation while, can cross segregation bar to provide 500mW and 330mW power respectively.

 

Graph 4: ADuM5020 and ADuM5028

 

ADuM5020 is used 16 bring SOIC of crural wide system to enclose, and to ADuM5028, what can choose is the smallest enclosing is the 8 SOIC that cite a base. ADuM5020/ADuM5028 offers 3V and 5V option of two kinds of power source, and 3kV Rms rated segregation.

 

Blast off to reduce radiation, ADuM5020/ADuM5028 has outstanding coil symmetry and coil drive circuit, conduce to the CM electricity that will carry segregation bar transmitting the smallest change. Enlarge frequency technology also is used to reduce some the noise chroma of specific frequency, diffuse radiation emissive energy more extensive frequency paragraph. In ferrite of sub end use low magnetism bead can reduce radiation to blast off further. During RE combines compasses test, these technologies can improve peak value and exact peak value to measure a level.

 

Graph 5: ADuM5020 and ferrite character curve

 

Graph 5 showed place the sub Duan Tieyang that standing by VISO and GNDISO to cite a base body magnetism bead. These ferrite have tall impedance inside wide frequency limits (1800Ω is when 100MHz, 2700Ω is when 1GHz) . These ferrite were reduced occasionally extremely effective radiate efficiency. If the graph is shown 6 times, because of ferrite the impedance of magnetism bead, annulus of CM electric current is reduced, occasionally extremely effective length shortens apparently, make occasionally extremely loss of efficiency, radiation blasts off decrease.

 

Graph 6: Magnetism bead comes to use ferrite reduce rare effect occasionally extremely

 

ADuM5020/ADuM5028 is offerred use namely model dc – solution of direct current source. The sexual price of this kind of solution is lower than tall, complexity, cover an area of an area small, and RE performance is excellent, in if designing cycle,bringing into products plan in the begining, the requirement that conduces to contented EMC code.

 

Come from the result of test room

 

ADuM5020/ADuM5028 is in according to CISPR22/EN55022 test guideline 10m has a test in half darkroom. The graph shows the 10m test room that is a model 7 times. According to standard regulation, ADuM5020/ADuM5028 evaluates PCB to be placed to be in 10m of dot of distance antenna calibration is far non-conductive n on workbench. Ensure to there is other and electric surface near DUT, because this is met,the influence checks a result. Graph the 8 peak value that indicated the tall emissive frequency that is used at deciding DUT scan. After these dots locate, can undertake peak value is measured allowing. During exact peak value is measured, workbench can rotate 360° , aerial height lifts from 1m 4m. The exact peak value that records worst case measures an outcome, ask to undertake comparative with limitative line.

 

Graph 7: The image of room of 10 M test and evaluate PCB

 

Ensure the radiate that can disturb DUT without plane of any peripheral equipment, metal or cable launchs a test. Evaluate to check ADuM5020/ADuM5028 board, use belt board the source current annulus that the circuit that carries low-pressure poor manostat will come to keep lesser, eliminate needless wiring.

 

Graph 8: —ADuM5020/ADuM5028 of peak value graph

 

Graph the 8 peak value that indicated the ADuM5020/ADuM5028 that captures below different configuration pursue. Because enlarge frequency technology was used in ADuM5020/ADuM5028, need notices broadband Duan Fan surrounds the energy inside to diffuse circumstance. Graph the measured value of 9 exact peak value that showed worst circumstance falls and CISPR22/EN55022B kind the abundant amount that limitative line photograph compares. ADuM5020 is 5V in output power source (500mW) , load falls for the circumstance of 100mA, passed CISPR22/EN55022 test in order to exceed the abundant amount of 5dB, increased to design flexibility greatly. Range of volume of this kind of abundant is very good, and recommend reach capacity of this kind of abundant, because be in different test establishment, the precision that tests the quality of the room, calibration and equipment may be put in difference, the likelihood is brought about measure result occurrence wave motion. If end item needs to have a test in different test room, and must accord with CISPR22/EN55022 standard, so this are crucial.

 

Graph 9: The measured value of exact peak value below worst circumstance and CISPR22/EN55022B kind the abundant amount that limitative line photograph compares

 

Products of next generation Isor series are offerred compact use namely model power source solution, need not launch limitation to satisfy radiation and use complex PCB form to restrain a technology. ADuM5020/ADuM5028 offers the dc that applies to segregation design – dc is used namely model power source solution, contented and the following radiate blasts off to ask with product standard:

 

● X CISPR 22/EN 55022 (B kind) : IT equipment

● CISPR11/EN55011 (B kind) : Industry, science and medical treatment equipment

● X IEC 61000-6-4: The radiate of environment of industry of general standard — projects a level

● X IEC 61000-6-3: The radiate of residence of general standard — , commerce and light industry environment projects a level

● IEC 61131-2: Can make up Cheng controller — the 2nd part: Equipment asks and check

● X IEC 621326: Use at measuring, the electric equipment of control and lab utility

— of requirement of ● X EMC the 1st part: General requirement

● IEC 60601-1-2: Medical treatment is electric equipment 1-2 part: The general requirement — of basic safety and basic function is add standard: Electromagnetism disturbs — requirement and test

● IEC 61800-3: — of system of drive of gearshift electric power the 3rd part: EMC asks and check a method specificly

● IEC 63044-5-1: Family expenses and construction report subsystem (HBES) reach building automation and control system (BACS) 5-1 of — part: EMC requirement, condition and test are installed

 

Reduce the complexity in keeping apart a design and contradiction

 

Designing segregation type power source may be a side that challenge sex has most in designing a process. Compose builds a solution to need balance all sorts of design requirement, and need abides by the whole world the code of many different areas asks. The sacrifice that makes from this often brought the negative effect of dimension, weight and performance side, perhaps reduced the capacity of contented EMC standard.

 

To satisfy EMC standard smoothly, can be in of design phase inchoate use the parts of an apparatus or appliance that has carried occupation standard test and verify. EMC should bring into a design in the process, is not after the event just considers. The inhibition that uses and so on of capacitance of such as bypass the technology can reduce electronic system to fight transient ability, increase cost and design complexity.

 

Products of next generation IsoPower series offer radiation to blast off restrain a technology, need not have bypass electric capacity, still can satisfy EN55022/CISPR22B kind standard requirement. ADuM5020/ADuM5028 uses enlarge frequency technology, can reduce the power level below aleatoric frequency. Of symmetry of coil of excellent design, transformer and body of oxygen of two low Xiaotie use conduce to reduce the CM electric current that crosses segregation bar to flow to layer of second ground connection. ADM5020/ADuM5028 satisfies CISPR 22/EN 55022 B kind requirement, have on 2 PCB make rich considerably quantity, the PCB class RE that need not use cost to hold high restrains a technology, because this can reduce cost.