Vishay VJ Safety Series


permitting high-temperature lead-free reflow soldering. Electromagnetic interference (EMI) is a major issue in power


supply design and therefore ceramic capacitors are very widely used in the industry. As an example, aimed at applications in demanding environments, such as in alternative energy, industrial/lighting, medical and telecommunications markets, which need to keep potentially disruptive or damaging line transients and EMI from susceptible equipment, Kemet has recently released a line of industrial-grade ceramic safety disc capacitors. Also suitable for suppressing mains supply line disturbances in motors, relays and switching power supplies, the 900 series of radial through-hole ceramic safety disc capacitors also offers reliable operation up to 125°


Kemet radial through hole ceramic safety disc capacitor


C.


Meeting the requirements of IEC 60384-14, safety-certified capacitors are classified as either X and/or Y types. Class X devices are primarily used in line-to-line (across-the-line) applications, where there is no danger of electric shock to humans should the capacitor fail, but could result in a risk of fire. The class Y capacitor is primarily used in line-to-ground (line bypass) applications, where failure of the capacitor could lead to danger of electric shock. Also designed for safety-certified applications is Vishay


Intertechnology’s VJ Safety series of surface-mount multilayer ceramic chip capacitors (MLCCs). The devices offer low profiles to save board space and fully meet the latest creepage distance requirements. The


17


devices are offered with C0G (NP0) and X7R dielectrics, each offering X1 / Y2 and X2 safety classifications with 250V AC voltage ratings. Capacitance values down to 10pF are available featuring a C0G (NP0) dielectric; high capacitances up to 12nF feature a X7R dielectric. The MLCCs can handle peak impulse voltages of 5000V (X1 / Y2) and 2500V (X2). As with most technology, there are often performance trade-offs; and size is always a key factor in electronics design. Reducing the size of capacitors while maintaining high voltage resistance and high capacitance is difficult because properties such as dielectric constants and insulation resistance degrade when applying high voltage to dielectric materials. However, AVX has introduced the first 1206 size 100V MLCC device that is capable of exhibiting


capacitance of 4.7μF and also withstanding operating temperatures of up to 125°


C. Designed for use in industrial


power supply circuits, the devices exhibit high voltage resistance, high capacitance, low ESR, ripple resistance and an extended lifetime. Based on the company’s proprietary X7S dielectric material has meant the reduction in the average diameter of dielectric particles by approximately 20% and also enhances the uniformity of its composition.


The 1206 MLCC, with dimensions of 3.2mm x 1.6mm x 1.6mm, features continues p 18 > focus magazine - issue 17


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