Knowledge points when selecting chip capacitors

Knowledge points when selectingchip capacitors

mlcc selection: just meeting the parameters is not enough

The general decision-making logic for purchasing goods is: whether it can be used, whether it is good or not, whether it is durable or not, and the price. In fact, this logic can also be applied to the selection process of mlcc: first, the mlcc parameters must meet the circuit requirements, and the second is whether the parameters and media can make the system work in the best state; thirdly, whether the incoming mlcc has defective products, and how reliable is it? ; Finally, whether the price has an advantage, and whether the supplier cooperates in a timely manner. Many design engineers don't pay attention to passive components, thinking that the parameters can be calculated only by theory. In fact, the selection of mlcc is a complicated process, and it is not easy to meet the parameters.

Selection elements

Parameters: Capacitance value, tolerance, withstand voltage, operating temperature, size

material

DC bias effect

Price and Availability

Different media properties determine different applications of mlcc

c0g capacitors have high temperature compensation characteristics, suitable for bypass capacitors and coupling capacitors

x7r capacitors are temperature stabilized ceramic capacitors for less demanding industrial applications

z5u capacitors are characterized by small size and low cost, especially suitable for decoupling circuits

The y5v capacitor has the worst temperature characteristics, but it has a large capacity and can replace the low-capacity aluminum electrolytic capacitor

Different media specifications such as c0g (np0), x7r, z5u, y5v are commonly used in mlcc, and different specifications have different characteristics and uses. The main difference between c0g, x7r, z5u and y5v is their filling medium. Under the same volume, the capacity of the capacitor formed by the different filling medium is different, and the dielectric loss and capacity stability of the capacitor are also different. Therefore, the capacitor should be used according to the different functions of the capacitor in the circuit. Use different capacitors.