Views:0 Author:Site Editor Publish Time: 2019-01-16 Origin:Site
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 grounded during installation, otherwise there is a danger 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 the normal condition. If the time 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.
Little experience in the design of electrolytic capacitors:
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 situation, and does not depend on the rated value of the filter circuit;
2. There must be no pads or vias directly under the electrolytic capacitor.
3. The electrolytic capacitor must not be in direct contact with the surrounding heating elements.
The applicable guidelines for aluminum electrolytic capacitors are as follows:
4. Aluminum electrolytic capacitors are divided into positive and negative poles. Reverse voltage and AC voltage should not be added. Non-polar capacitors should be used where reverse voltage may occur.
5. For places where fast charging and discharging are required, aluminum electrolytic capacitors should not be used. Specially designed capacitors with longer life should be selected.
6. Should not use overload voltage
a. DC voltage Yuwenbo voltage superimposed sewing voltage is lower than the rated value.
b. When two or more electrolytic capacitors are connected in series, consider using balanced resistors so that the voltage across each capacitor is within its rated range.
7. When designing the circuit board, it should be noted that there should be no lines on the upper end of the capacitor and the explosion-proof valve, and a clearance of more than 2 mm should be left.
8. Electrolysis is also the main chemical solvent and electrolytic paper are flammable, and the electrolyte is conductive. When the electrolyte comes into contact with the pc board, the wiring on the pc board may be corroded. So that they smoke or catch fire. Therefore there should be no lines under the electrolytic capacitor.
9. Design the circuit board to the back to confirm that the heating components are not close to the aluminum electrolytic capacitor or electrolytic capacitor.