Conducted and radiated tests from Maxwell's equations perspective

CISPR standards require testing each product from a conducted and radiated fields perspective. CISPR 11 and CISPR 32 require testing the conducted noise from 150KHz up to 30MHz. CISPR 25, addressing automotive products, requires testing the systems up to 108MHz. To complicate the understanding the MIL standards require testing the conducted noise up to 400MHz. Thus the question of what makes a noise conducted or radiated is legitimized. Things can get clarified if the Maxwell’s equations are taken into account to better analyze the effects of the conducted and radiated noise and from where they come from.

DC-DC Converter - SYNC pin from EMC perspective

Among the engineering challenges and trade-offs, beside the technical ones, there is always the system cost. The main design goal is typically to achieve what the marketing department asks for, with the minimal cost. This will enable a cheaper product and would allow a better revenue margin by selling the product in the market. The SYNC pin is a typical feature offered by high current DC-DC converters (typically from 2A and higher) that enables reducing the size of the input capacitance in case multiple DC-DC converters are required. The article will introduce how and why the SYNC feature is used, and which benefit may bring also from the EMC perspective.

CISPR Standards

    Introducing an electronic system within the European market is getting challenging from the design perspective. Indeed it is not enough to design a working system, the system must comply with several regulations. In particular what is required for a certain product is defined by the European directives. The European directives are publicly available and can be found online by Euro Lex. The directives are very high level regulations but are a “must to be compliant” with. For an engineer looking for numbers, the directives are not the answer they may search for. Indeed the directives describe general needs that a system may support, but not how to achieve it or test it to make sure that you are compliant. The directives only require the designer to test the product with the “state of the art” knowledge, but do not specify what those are. Once you are compliant with the directives you may apply the CE marching on the product that can be sold in the European market. It is important to highlight that multiple directives generally apply to the same product, thus some time may be needed to understand which ones really apply to the product and which not.

Dallo schema elettrico al PCB

Realizzare un sistema elettronico, necessita il passaggio per varie fasi e un certo numero di iterazioni al fine di rendere il progetto finale quanto più funzionale possibile. Le varie fasi possono variare a seconda dell’applicazione e soprattutto se il progetto debba essere catalogato come “Maker” o “professionale”. Frequentemente in sistemi Maker, non ci si preoccupa molto della fase progettuale e si pone ad essa poco tempo. La realizzazione è spesso anche fatta velocemente al fine di realizzare pezzi unici. Quando si voglia realizzare un sistema professionale le cose cambiano. La fase progettuale diventa una fase importante della progettazione come anche la fase di test del sistema, al fine di verificare che le specifiche di progetto siano rispettate.