SMD capacitor is a kind of capacitor material. The full name of the chip capacitor is: multi-layer (multilayer, laminated) chip ceramic capacitor, also called chip capacitor, chip capacitance. It is a common capacitor in daily life, and it has a wide range of applications, and it can be seen in various electronic fields.
1. Decoupling, divided into driven source and driven load. If the load capacitance is relatively large, the drive circuit will charge and discharge the capacitor to complete the signal jump. When the rising edge is relatively steep, the current will be relatively large, so that the drive current will absorb a large power supply current. Compared with normal conditions, this kind of current is actually a kind of noise, which will affect the normal operation of the previous stage. This is the so-called "coupling".
2. Bypass, an energy storage device that provides energy for local devices, it can make the output of the voltage stabilizer uniform and reduce the load demand.
3. Filtering. Theoretically, the larger the capacitance, the smaller the impedance, and the higher the passing frequency. But in fact, most of the capacitors over 1μF are electrolytic capacitors, which have a large inductance component, so the impedance will increase when the frequency is high. Sometimes you will see a large electrolytic capacitor with a small capacitor connected in parallel. At this time, the large capacitor is connected to the low frequency and the small capacitor is connected to the high frequency. The function of the capacitor is to pass high impedance and low impedance, and pass high frequency to block low frequency. The larger the capacitance, the easier it is to pass low frequencies. Specifically used in filtering, a large capacitor (1000μF) filters low frequencies, and a small capacitor (20pF) filters high frequencies.
4. Energy storage, the charge is collected by the rectifier, and the stored energy is transferred to the output terminal of the power supply through the lead of the converter. Most capacitors do not have this ability.
[What is the difference between chip capacitors and ceramic capacitors]
Ceramic chip capacitors are capacitors that use ceramic materials as a medium, coated with a metal film on the surface, and then used as electrodes after high-temperature sintering. Used in high-stability oscillating circuit, as loop, bypass capacitor and pad capacitor. The advantage is stability, good insulation, and high voltage resistance; the disadvantage is that the capacity is relatively small.
SMD capacitors can be divided into variable capacitors and fixed capacitors. Most capacitors distinguished by intermediate insulating materials are directly named as insulating materials. When selecting, it should be noted that some capacitors are not suitable for high-frequency circuits, and some capacitors have polarities. Pay attention to the connection method when connecting to the circuit, and the details should be done well.