Characteristic comparison between aluminum electrolytic capacitor and tantalum electrolytic capacitor
Aluminum electrolytic capacitor has large capacitance, large series resistance, large inductive reactance and is sensitive to temperature. It can be used in low frequency filtering (when the high frequency is high, the effect of parallel filtering of electrolytic capacitor is worse than that of low frequency). Aluminum electrolytic capacitor has polarity, so the correct polarity must be ensured during installation, otherwise there is a risk of explosion.
Compared with aluminum electrolytic capacitor, tantalum electrolytic capacitor has obvious advantages in series resistance, inductive reactance and temperature stability. 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, the rated working voltage + 50V is taken as the surge voltage, which is the voltage guaranteed by the manufacturer and can withstand this voltage in a short time. When the capacitor is in surge voltage, the current will be very large, usually 10 ~ 15 times of the normal situation. If the time is too long, it will burst. Therefore, the voltage of aluminum capacitor should be slightly higher, and the actual working voltage should be 70 ~ 80% of the nominal voltage.
Design experience of electrolytic capacitor:
1. The voltage value of electrolytic capacitor in the filter circuit is 1.2-1.5 times of the noise peak value according to the specific situation, not according to the rated value of the filter circuit;
2. There shall be no pad and via hole under the electrolytic capacitor.
3. The electrolytic capacitor shall not be in direct contact with the surrounding heating elements.
The applicable guidelines for aluminum electrolytic capacitors are as follows:
4. The aluminum electrolytic capacitor is divided into positive and negative poles. Reverse voltage and AC voltage are not allowed to be applied. Non polar capacitor should be used where reverse voltage may occur.
5. Aluminum electrolytic capacitors should not be used in places where rapid charging and discharging are needed. Capacitors specially designed with longer service life should be selected.
6. Overload voltage should not be used
a. The sewing voltage of yuwenbo voltage superposition is lower than the rated value.
b. When two or more electrolytic capacitors are connected in series, a balance resistor should be used to make the voltage on each capacitor within its rated range.
7. When designing the circuit board, it should be noted that there is no line at the upper end of the explosion-proof valve, and a gap of more than 2mm should be left.
8. The main chemical solvents and electrolytic paper in electrolysis are flammable, and the electrolyte is conductive. When the electrolyte contacts with the PC board, it may corrode the circuit on the PC board. So as to cause smoke or fire. Therefore, there should be no line under the electrolytic capacitor.
9. It should be confirmed that the heating components are not close to the aluminum electrolytic capacitor or below the electrolytic capacitor.
