In some home appliance design applications, capacitors play a key role in filtering and decoupling. Filtering anti-jamming focuses on purifying the outside noise, while decoupling prevents the front and back circuit current and noise levels from changing. Most people often confuse the two. Therefore, it is very necessary to choose a good capacitor factory. Next, we will introduce the power supply structure of household appliances to you:
It is assumed that the household appliance power switches A and B are power circuits. The current passes through C1 and then passes through a section of the circuit board. Separate the two ways to provide A and B respectively. The ripple from the power switch is relatively large, so we use C1 to filter the power supply to provide a stable voltage for A and B. C1 needs to be placed as close as possible to the power supply. Both C2 and C3 are bypass capacitors that act as decoupling filters. When A needs a large current at a certain moment, if there is no C2 and C3, the voltage at the A terminal will become lower due to the inductance of the line, and the voltage at the B terminal is also reduced by the voltage at the A terminal, so the partial circuit The current change of A causes the power supply voltage of the local circuit B, thereby affecting the signal of the B circuit. Similarly, the current change in B also interferes with A. This is the "common path coupling interference."
After the addition of C2, when the home appliance design needs an instantaneous large current, the capacitor C2 can temporarily supply current to A. Even if the common circuit part of the inductance exists, the voltage at the A terminal will not drop too much. The impact on B will also be much reduced. Therefore, the current bypass acts as a decoupling. Decoupling capacitors need to meet two requirements, one for capacity requirements and the other for equivalent series resistance requirements. That is to say, a 0.1uF capacitor decoupling effect may not be as good as two 0.01uF capacitors. Moreover, 0.01uF electrolytic capacitors have lower impedance in higher frequency bands. If a 0.01uF capacitor can meet capacity requirements in these bands, it will have better decoupling effect than 0.1uF capacitors.
Many high-speed chip design guidebooks with more pins will give the parasitic coupling requirements of home appliance design. For example, a 1kpcs pin ball array package requires 3.5 ceramic capacitors for 3.5KV power supply, and several large capacitors. Capacitors, the total capacity should be 210uF or more. Shenzhen Jinmaoyuan Weiye Technology Co., Ltd. has only focused on the production and sales of resistors and capacitors for 13 years. Is a professional capacitor manufacturer, guarding the good life for technology, better guarding the safety of the people around us.