![]() ![]() However, cost of doing this may be high in some cases. The best strategy is to get the worst-case limits and design the product for them. Knowing the standards helps in designing the packaging such that the products meet the required standards. However, from the electronic packaging point of view we need to know what standards the products should meet. While each country has its own standards, they do not vary much in values. With increased use of electronics in our daily life, compliance to these standards ensures that the users are safe and products do not pollute and affect the working of products in the vicinity. Similarly, there are voltage discharge levels that a product should withstand without getting damaged. Standard bodies like FCC (Federal Communication Commission) in the USA, CE (Conformitè Europëenne) in Europe, and VCCI (Voluntary Control Council for Interference) in Japan specify the amount of radiation an electronic product can radiate, or the amount of radiation an electronic product should withstand without any permanent failure. These acronyms define how a product can unintentionally become a source of radio frequency waves generation, or how it can become a victim of radio frequency waves that come from various sources in the environment.ĮSD defines how robust a product is to withstand the static voltage discharge that is accumulated by the human operator. This article explains the causes of failure as well as the remedies.ĮMI stands for electromagnetic interference, EMC for electromagnetic compliance, and ESD for electrostatic discharge. ![]() The designers need to take care of such international standards as FCC, CE, and VCCI if they want their products to succeed in international markets. if you wan't me to share the board layout please provide me with a non public way of sharing it (e-mail).The effects of electrostatic discharge and interference is often ignored by designers, which results in their rejection, especially in global markets. Is there an easy way to make the LNK306 MOSFET less senstive ? The IC/design seems verry susceptible to oscillation based on electric/inductive coupling. After doing some more tests we found that adding a loos wire with a lengt of about 10 centimeters to the source pin of the MOSFET it also causes the otherwise normally functioning design to start oscilllating. What we did find is that when we connect a differential probe (50Mohm / 1,25pF) between the Drain and Source of the MOSFET this design also starts to oscillate. We've been trying to fiend the key difference between the designs and have not found anything critical yet. We have another design incorporating the LNK306 which does not have this oscillation. ![]() we tried multiple filters this does not prevent the oscillation of the MOSFET and has only limited effect on the peak amlitude of the oscillation measured in the conducted emissions test. ![]() The ripple on the 24V output is well below 200mV and does not contain the 800kHz oscillation. The output voltage of our circuit is 24 volt with an approximate load of 15~50mA depending on the state of the application. We've changed the layout (groundplane) and the inductors (different types) but this only results in the frequency slightly changing to a higher/lower frequency but not an increase or decrease of this signal.Ĭan you give us any pointers with regard to origin of this oscillation in our implementation/the LNK306 and how to resolve this. When checking the design with a near field H and E probe the 800kHz signal is the strongest measured at L4 (see attached schematic). The LISN measurement clearly shows a 966kHz spike above the switching signal. The attached FFT image shows the level of noise is around the same level of the normal switching noise but the PI filter on the input does net prevent his from getting fed back to the mains grid.ĭuring startup there is no oscillation on the output, there is a very steady/clean switching signal until it reaches the required voltage. The oscillation frequency is affected by changing components and/or the board layout(but the amplitude not so much).īy using the recommended filtering and board layout we can get the normal switching noise well below the CISPR limits but the 800kHz peak amplitude remains unchanged. The oscillation frequency does not drift / change over time, it is also not depending on the amount of power drawn from the output. In our application the output of the chip creates an oscillation around 800kHz which goes out of spec during Conducted Emissions testing. I've got a question with regard to the LNK306. ![]()
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |