Capacitor is a switching power supply is no more than ordinary devices, it can be used to reduce ripple noise, can be used to improve the stability of the power supply as well as transient response, however, there are many types of capacitors, how to quickly select through the skills, and product reliability and high performance and stability?

　　First, the capacitor type of understanding

　　A general understanding of the types of capacitors, capacitors in the selection of capacitors to help the rapid screening of capacitor types.

　　Capacitor types are more, according to the package has chip capacitors, plug-in capacitors, according to the medium of ceramic capacitors, electrolytic capacitors, mica capacitors, etc., according to the structure of the situation, there are fixed capacitors, semi-fixed capacitors, variable capacitors.

　　In front of so many choices, people are prone to suffer from selection difficulties syndrome, but don't worry, in the switching power supply, we use the most is ceramic capacitors, electrolytic capacitors and tantalum capacitors, understand the types of capacitors next is to understand some of the performance parameters of capacitors.

　　Second, the understanding of the key parameters of capacitance

　　Understand the inherent key parameters of capacitors, in order to quickly select, reliable use, all the key parameters of capacitors are the same, including capacitance, capacitance withstand voltage value, capacitance ESR, capacitance accuracy, capacitance allowable operating temperature range.

　　Third, the selection of capacitors in the switching power supply to understand the characteristics of the capacitor itself

　　In the switching power supply design, the use of the highest frequency of capacitance is ceramic capacitors, electrolytic capacitors, tantalum capacitors, you need to understand the differences in their characteristics in order to quickly select.

　　Ceramic capacitor capacitance is smaller, high frequency characteristics, a wider range of operating temperatures, ESR is smaller than electrolytic capacitors, small size, no characteristics;.

　　Electrolytic capacitor capacitance can be made larger, but the operating temperature range is narrower, ESR is larger, there is polarity.

　　Tantalum capacitors ESR is the smallest, the capacitance value can be larger than ceramic capacitors, polarity, poor safety performance, easy to fire.

　　Understand the characteristics of the above three kinds of capacitors, in the use of them can be easily.

　　Fourth, the selection of capacitors in the switching power supply but also to understand the use of bad conditions

　　The use of capacitors is also divided into the internal environment and the external environment of the circuit, the internal environment of the circuit, including frequency, voltage, current, capacitance in the circuit of the main role, etc.; according to the frequency of the circuit can determine the type of capacitance; according to the value of the voltage can be determined by the selection of the capacitor voltage withstand value; in the circuit can be used to refer to the main role in the selection of the capacitance of the capacitor; according to the circuit outside the use of capacitors in the selection of bad conditions, the product working environment temperature, safety regulations. Product operating ambient temperature, safety requirements, etc., can be used to narrow the range of capacitor selection.