What is the role of the input capacitor in the DCDC circuit? What is the role of the output capacitor?

小太阳yy

What is the role of the input capacitor in the DCDC circuit? What is the role of the output capacitor? [Copy link]

 

What is the role of the input capacitor in the DCDC circuit?

What is the function of output capacitor? The more I learn, the more confused I become.

cuoguohaoduo

Decoupling capacitors to remove high-frequency interference and store energy

maychang

Note: This DCDC circuit is a Buck circuit. The input current of the Buck circuit (pin 3 of the chip) is intermittent, so the current taken from the input terminal is also intermittent. For this reason, a capacitor or multiple capacitors are connected in parallel to the input terminal. When the pin 3 of the chip is powered, the capacitor supplies power to the chip. When the pin 3 of the chip is not powered, the capacitor is charged by VIN, which can greatly reduce the change of the current at VIN.

maychang

There are also multiple capacitors in parallel at the output of this circuit, and their role is similar to that of the input capacitors. It should be noted that the fluctuation of the output voltage is called ripple. You have asked many times about the output ripple of the switching power supply. What is the role of the capacitors at the output of this Buck circuit? If you have a little understanding of output ripple, you should not ask this question again.

小太阳yy

maychang posted on 2023-3-15 10:26 There are also multiple capacitors in parallel at the output of this circuit, and their function is similar to that of the input capacitor. It should be noted that the fluctuation of the output voltage is called ripple. You have asked many times...

Yes, yes, I feel like the more I learn, the more confused I become.

qwqwqw2088

Input and output capacitance can be understood as

Comparing electric current to water flow, capacitor is a reservoir, which can control the smoothness of water flow to a certain extent, that's all...

Or capacitor is a reservoir

If it is called juice, the metaphor may not be appropriate

chunyang

The function is filtering and decoupling to reduce power supply ripple and noise and stabilize the feedback loop.

光为电子

Input and output voltage ripple is very important. The input voltage mostly provides energy for the DC/DC chip. Adding a large ceramic capacitor at the input pin can provide decoupling and have the ability of large capacitance to suppress input power ripple. Output ripple will affect the stability of the load. If the load is a CPU processor, it requires a very low voltage with fast precision adjustment, which puts high demands on the output power supply.