What is a chip capacitor? What does it do?
SMD capacitor is a kind of capacitor material. SMD capacitors are called: multilayer (multilayer, laminated) chip ceramic capacitors, also known as SMD capacitors, chip capacitors. It is a common capacitor in our lives and has a wide range of applications. SMD capacitors can be seen in various electronic fields.
Decoupling, also known as decoupling. From the circuit point of view, it can always be divided into the driving source and the driven load. If the load capacitance is relatively large, the drive circuit needs to charge and discharge the capacitance to complete the signal jump. When the rising edge is relatively steep, the current is relatively large, so the drive current will generally absorb a large power supply current. The inductance and resistance (especially the inductance on the chip pins will bounce). This current is generally a kind of noise relative to the normal situation, which will affect the normal operation of the previous stage. This is the so-called "coupling".
The bypass capacitor is an energy storage device that provides energy for the local device. It can uniformize the output of the regulator and reduce the load demand. The bypass capacitor can be charged and discharged. If you want to reduce the impedance, place the bypass capacitor close to the power supply pin and ground pin of the load device.
Theoretically (that is, assuming that the capacitor is a pure capacitor), 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 generally to pass high resistance and low resistance, 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 energy storage capacitor collects the charge through the rectifier and transfers the stored energy to the output terminal of the power supply through the lead of the converter. This is the function that most capacitors have. Nowadays, there are many specifications of chip capacitors, and there are various types of chip capacitors to choose from, such as capacity and temperature resistance.
[Differences from ceramic capacitors]
A ceramic chip capacitor is a capacitor that uses ceramic materials as a medium, coats a metal film on the surface of the ceramic, and then sinters at a high temperature as an electrode. Generally used in high-stability oscillating circuits, as loops, bypass capacitors and pad capacitors. Its advantages are stability, good insulation, and high voltage resistance; its disadvantage is that the capacity is relatively small.
[Methods to judge good or bad]
Method 1: A safer way. Use the two-pole gear of a multimeter to connect one pin to the ground and the other pin to measure the two ends of the capacitor, indicating a short circuit.
Method 2: If the small patch capacitor is short-circuited, it can generally be judged by online measurement with a multimeter. If it is an open circuit, because the capacity is too small to be measured with a multimeter, you can use an electric pen to connect to the 220V live wire, and put the pin of the patch capacitor on the cap of the electric pen to see if the neon bulb is glowing. The light-emitting capacitor is Okay, otherwise the circuit breaks. 220v voltage, don’t experiment on the board.
Method 3: The resistance value is infinite, the resistance value is zero and the tweet is bad, and the others should have some small changes.
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