Factors to be considered for selecting film capacitors

A lot of people will have such a perception of film capacitors is a panacea for noise related problems, but the value of film capacitors is not limited to that. Designers often think of adding a few capacitors to solve most of the noise problems, but seldom consider the parameters other than capacitance and voltage ratings. However, as with all electronic devices, film capacitors are not imperfections. On the contrary, the capacitance will bring about the problem of the parasitic equivalent series resistance (ESR) and inductance (ESL), and the capacitance varies with the temperature and voltage, and the capacitance is also very sensitive to the mechanical effect.

In the voltage regulator, the following three types of capacitors are usually used as voltage input and output bypass capacitors: multilayer ceramic capacitors, solid tantalum electrolytic capacitors and aluminum electrolytic capacitors. These factors must be considered when designers choose bypass capacitors, as well as other applications of film capacitors for filters, integrators, sequential circuits, and actual capacitance values. Improper selection may lead to instability of the circuit, excessive noise and power consumption, shortened product life cycle and unpredictable circuit behavior.

When choosing capacitors, we should avoid weaknesses and use them to eliminate unnecessary troubles.