The capacity of the aluminum electrolytic capacitor is relatively large, the series resistance is large, the inductance is large, and it is sensitive to temperature. It is suitable for occasions where temperature changes are not large and the operating frequency is not high (not higher than 25 kHz). It can be used for low-frequency filtering (the parallel filtering effect of electrolytic capacitors is lower at higher frequencies). Aluminum electrolytic capacitors have polarity and must be properly polarized during installation, otherwise there is a risk of explosion.
Compared with aluminum electrolytic capacitors, tantalum electrolytic capacitors have obvious advantages in series resistance, inductive reactance, and stability to temperature. However, its operating voltage is low.
1.3 times of the rated voltage of the aluminum electrolytic capacitor is used as the surge voltage of the capacitor. When the working voltage is higher than 160V, it is the rated working voltage +50V as the surge voltage. This is the voltage guaranteed by the manufacturer and can be tolerated in a short time. Voltage. When the capacitor is in surge voltage, the current will be very large, usually 10~15 times of normal. If it is too long, it will explode. Therefore, the aluminum capacitor should be selected to be slightly higher, and the actual working voltage is 70~80% of the nominal voltage.
The applicable guidelines for aluminum electrolytic capacitors are as follows:
1. In the filter circuit, the electrolytic capacitor takes the voltage value as 1.2--1.5 times of the noise peak according to the specific conditions, and does not depend on the rated value of the filter circuit; 2. There must be no pads and via holes under the electrolytic capacitor.