Three-terminal capacitors target automotive safety sytems

January 16, 2017 // By Christoph Hammerschmidt
Preventive safety systems and advanced driver assistance systems (ADAS) frequently require the use of three-terminal ceramic multilayer capacitors for reliability reasons. These application fields is what passive components vendor Murata is addressing with its new NFM18HC products.

The use of a three-terminal capacitor as opposed to a conventional two-terminal one addresses specific needs associated with the application. The power circuit of a processor requires many decoupling capacitors to reduce that impedance, thereby suppressing fluctuation of the power voltage, and increasing stability. As the processing speed of processors increases as a function of theur operating frequency, the control of impedance across a wide frequency band becomes very important. One problem is that you need dozens/hundreds of decoupling capacitors which occupy a lot of space.

The three-terminal multilayer ceramic capacitor has a smaller equivalent series inductance (ESL) than conventional two terminal multilayer ceramic capacitors, thus reducing the overall impedance. This lowers the number of capacitors that need to be used for higher frequency bands which frees up valuable board space for other components, making it possible to reduce the PCB area required.

Making use of this characteristic has resulted in its wide adoption for smartphones and other devices where compactness and high density are needed for mounted high-speed processors.  The use of three terminal multilayer ceramic capacitors in the automotive market has surged recently due to the demand for high performance processors and smaller electronics. This demand has driven the increase in high-functioning multitasking onboard equipment such as ADAS, preventive safety systems, and in-vehicle infotainment (IVI).

Murata’s NFM18HC series capacitors provide a three-terminal multilayer ceramic capacitor in the company’s smallest 1.6 x 0.8 mm package. It also meets the AEC-Q200 standard for use in high reliability automobile applications, contributing to further size reduction and tighter density for automotive electronics.

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