The role of chip capacitors in the electrical field (II)

3. To the Lotus root, also known as the solution Lotus.  From the circuit, it can always be distinguished as the source of the drive and the load being driven. If the load capacitance is relatively large, the drive circuit must charge and discharge the capacitor to complete the signal transition. When the rising edge is steep, the current is relatively large, so the driven current will absorb a large supply current, due to the circuit. The inductance, the resistance (especially the inductance on the chip pin, will produce a rebound), this current is actually a kind of noise compared to the normal situation, which will affect the normal operation of the previous stage. This is the coupling. The decoupling capacitor acts as a battery to satisfy the change of the drive circuit current and avoid mutual coupling interference. Combining bypass and decoupling capacitors will be easier to understand. The bypass capacitor is actually decoupled, except that the bypass capacitor generally refers to the high-frequency bypass, which is to improve the low-frequency leakage prevention path for high-frequency switching noise. The high-frequency bypass capacitor is generally small. According to the resonant frequency, it is generally 0.1u, 0.01u, etc., and the decoupling capacitor is generally large, 10uF or larger, which is determined according to the distributed parameters in the circuit and the variation of the driving current. Bypass is to filter the interference in the input signal, and decoupling is to filter the interference of the output signal to prevent the interference signal from returning to the power supply. This should be their essential difference.

4. The energy storage capacitor collects charge through the rectifier and transfers the stored energy through the converter leads to the output of the power supply. Aluminum electrolytic capacitors with a voltage rating of 40 to 450 VDC and a capacitance value between 220 and 150 000 uF are more commonly used. Depending on the power requirements, the devices are sometimes used in series, in parallel, or a combination thereof. For power supplies with power levels above 10 kW, bulky screw-type terminal capacitors are typically used.