Power source development is a technical work, also be a tired work, the hard to avoid when the job is multifarious can make a few elementary small mistakes. These are wrong, can bring about a series of chain-reacting, need purchases the numerous branch such as the ministry, production ministry, PM, ministry that taste a canal, business department, engineering department to cooperate, in order to correct that your small error. Article author will share him to work in power source of 10 years of research and development for everybody in, accumulated a few practical experience, hope to be helped somewhat to everybody.

 

1.Transformer blueprint, PCB, principle pursues this 3 person transformer flying line date needs to agree, this is to bring compasses attestation demand. The meeting when a lot of engineers are applying for to install compasses attestation to submit a data makes this mistake.

 

2.The release resistor of X capacitance needs to put two groups. Attestation of UL62368, CCC asks to disconnect the rudimental voltage that a group of resistor check X capacitance again.

This is a mistake that a lot of novices can make, amend can change PCB Layout afresh only, waste oneself and the time that purchase make a proof.

 

 

3.The PCB aperture of transformer flying line needs to consider diameter of the biggest flying line, when necessary obligate two groups one big one small PCB hole, avoid to assemble difficulty or problem of solder of sky crossing furnace.

 

Install compasses application attestation to be able to have a series normally, file a series e.g. 24W, include 4.2V-36V voltage among them paragraph, the way of flying line line that exports small electric current of low-pressure 4.2V big electric current and high-pressured 36V is different.

 

Computation of diameter of many flying line consults as follows form:

 

 

4.The PCB aperture that outputs DC wire needs to consider diameter of the biggest wire, avoid to assemble difficulty.

 

Because your PCB may be used in different electric current paragraph go up, the wire that for instance 5V/8A and 20V/2A use is different.

Reference is as follows form:

 

 

5.Circuit is debugged, the block value of many paralell connection should design resistor of OCP current limliting same, the power of that resistor susceptive with block greater value is greater.

 

6.Circuit design, the rectangle of aperture make it that carbon fin cites a base is elliptic (experience value: 2*1mm) , avoid to assemble difficulty.

 

Convenient radiator has elliptic opening a mobile space, this is very advantageous to assemble and crossing furnace.

 

7.Circuit is debugged, when unusual test, output voltage or OVP design should be less than 60Vac (Vpk) /42.4Vdc (Vrms) , this is to bring compasses demand.

The novice compares easy oversight, the product that applies for attestation so must do OVP test, catch output instant weaveform.

 

8.Circuit design, electroanalysis the distance of explosion proof aperture of capacitance is more than 2mm, horizontal is bandy-legged leave 1.5mm. General and regular corporation has this demand, the problem Japan of explosion proof aperture takes seriously quite, special situation except.

 

9.Circuit is debugged, the circuit that outputs wave of filter having LC needs ageing to affirm ripple, if ripple is unusual,adjust annulus road please. This are very important, this problem often is encountered before me, ripple of the test after ageing yield a line can become tall, the phenomenon is annulus road concussion.

 

10.Circuit is debugged, when diode is shunt-wound, when should testing open a way of breakdown of a diode, of generation unusual (include the two diode) in TO-220. Small company won’t make this motion commonly, an outstanding product is to want withstand of any test.

 

11.Circuit design, if PCB space is ample, design please kill all installing compasses standard, revise a number in order to reduce PCB.

 

Hypothesis some product accords with UL60335 standard only, if the client hopes to satisfy UL1310, need revises PCB Layout and go off with installs compasses cable equipment. If accord with of all kinds standard namely at the beginning, the job from the back will be a lot of more comfortable.

 

12.Circuit design, ESD designs standard of ±15KV of osculatory ±8KV/ air, reduce sequel to rectify and reform a frequency.

Like flying benefit riverside such client asks to ESD very severe, hear of Fuji health still need to achieve ±20KV, where day has demand of this kind of client, you get busy period of time again.

 

13.Circuit design, when designing transformer, VCC voltage is owed in what carry voltage gently to want to be more than IC pressure close voltage to be worth. Judgement carries VCC voltage to need to be more than chip to close the 5V of voltage to control for nothing, affirm to chip cannot is more than to control protective cost too when be fully loaded with at the same time.

 

14.Circuit design, the design is common transformer needs to consider the VCC voltage when using tension of the biggest output, the VCC when microtherm has a little NOSIE can be touched strike OVP action.

 

If your product 9V-15V is common a transformer, affirm VCC voltage and power are in charge of compression please.

 

15.Circuit is debugged, rcs and Ccs value cannot pass big, can cause VDS to exceed opportunity of blast of the biggest compression otherwise.

 

Time of concealed of disappear of LEB forward position is set short, the time that compares aiguille pulse is short still, that does not have the effect still is meeting miscarriage of justice; If set,grew, cross the effect that spread not to rise to protect truly.

 

The RC value of Rcs and Ccs cannot exceed the Delay of 1NS, when outputting short circuit otherwise, when Vds meeting comparing is fully loaded with, return tall, exceed MOSFET the biggest compression creates scamper opportunity possibly.

 

The Delay of experience value 1nS is approximated 1;

K is right 100PF, also be equal to 100R to 102PF.
 

16.When drawing platelet, the part of 90 degrees of corner that makes a base in platelet increases bore of a circle, convenient assemble. If pursue:

 

Objective graph

 

 

Actual assembly drawing

 

Such doing can make platelet and PCB big board between close together joint, won’t have float tall appearance.

 

17.Circuit design, xiaoteji’s carbon fin can receive output anode line, the Xiaoteji that such iron seal need not be isolated from mat and insulation bead.

 

18.Circuit is debugged, the RCD of 15W above power is absorbed do not use 1N4007, because of 1N4007 speed slow 300uS, pressure fall big also 1.3V, the temperature in ageing process is very high, easy invalidation creates scamper opportunity.

 

19.Circuit is debugged, the compression of wave capacitance sends output filter to need less to accord with 1.2 times surplus, avoid exert oneself quantity is produced have attaint appearance.

Was to make this very elementary mistake before, 14.5V output uses 16V compression electric capacity, the quantity produces the capacitance be no longer in force that has 1% undesirable.

 

20.Circuit design, when large electric capacity or horizontal of other capacitance make it, if bottom has jump the line needs to be put in negative pole potential, such jumping the line need not be used wear bushing, save cost.

 

21.Rectification bridge caboodle, diode or Xiaoteji, brilliant yuan size component acknowledgment or there should be a description in BOM watch, be like 67mil (reason: The canal accuses consistency of supplier deliver goods, prevent a supplier jerry, influence product efficiency) .

 

Those who make a person vexed is a supplier play tricks, bring about one whole batch tried yield product not to cross 6 level can effect, the reason is brilliant of interior of Xiao Te radical yuan with small bring about.

 

22.Circuit design, snubber capacitance, because discrepant phonic problem, capacitance of preferential use Mylar, this is one of methods that handle different news.

 

23.Circuit design, if the resistor that start is used before rectification, want to add the resistance that strings together a hundreds of K. When resistor short circuit, won’t cause IC and MOSFET damage.

 

Circuit graph

 

24.Circuit design, high-pressured large electric capacity and position of capacitance of ceramics of a 103P, reason: Have certain effect to radiation 30-60MHz. If the space allows, can take a place to PCB Layout, convenient EMI is rectified and reform.

 

25.When undertaking EMS project checks, need a test to give the largest order of the product, damage till the product till.

For example ESD be struck by lightning, must hit till the product damages, had made relevant record, see product surplus how many have, accomplish know fairly well.

 

26.Circuit design, when unusual test, short circuit open a way if a certain component still has output voltage to want to undertake LPS checks, shed a dot to cannot exceed 8A too (exceeding 8A is to cannot apply for LPS) .

 

27.Install compasses prototype opening case, component of all and optional plug-in unit wants mount to be used for taking a picture, line of L, N and DC line and PCB point white glue are fixed.

This is a mistake that often makes, often of an interest send tripartite orgnaization sample, will be answered back and forth from the back change come to those who go change.

 

28.Circuit is debugged, the PSR when cold machine needs 1.15 times electric current to be able to switch on the mobile phone, SSR needs 1.3 times electric current to be able to switch on the mobile phone, after avoiding ageing, start undesirable. A lot of chip can realize PSR now “ 0 restore”OCP electric current, for instance ME8327N, have “ 0 restore”Function of OCP electric current.

 

29.Circuit design, notice use Y capacitance total capacity please, cannot exceed 222P, because have the effect of leakage current. Be aimed at not Tongan compasses, leakage current requirement is different also, need when the design particularly advertent.

 

30.Stimulate develop filling structure instead, transformer B value needs to be less than 3500 gauss, if transformer is saturated all movements will out of control, it is normal that following different pictures are, right graph is saturation.

  

 

The magnetism saturation of transformer must affirm, chongzhongzhi is heavy, this is safeguard of first safety performance, the magnetism saturation that has included to shed a point, switch on the mobile phone the magnetism of the magnetism saturation below the magnetism saturation of the instant, magnetism saturation that outputs short circuit, high temperature, high low pressure is saturated.