What is the power adapter ripple? How to control the generation of ripple?
Let’s explain what the ripple is? Why does the power adapter produce ripple? The power adapter ripple can be observed with its practical corresponding equipment, which is called an oscilloscope. As we can see that when the power adapter is working, the voltage will fluctuate slightly, which is similar to the water ripple, that is why it is called ripple. Are there any affects if the power adapter ripple appear? In fact, there are some ripples even for the best power adapter products, but some of them are obvious, and some are faint only. Generally speaking, the larger the voltage, the greater the ripple. The ripple is the AC component of a DC voltage. The AC component will be generated due to unclean filtering and then ripple.
In general, for 5V products, the power supply ripple is generally controlled below 100mV, and for 12V products, the maximum ripple is generally 120mV. So how do we control the generation of power adapter ripple?
1. we can increase the inductance and output capacitor filtering. Speaking simply, because the current fluctuation in the inductor is inversely proportional to the inductance value, and the power adapter ripple is inversely proportional to the output capacitance value, then, we can add larger inductance and capacitance to reduce power adapter ripple.
2. Adding a capacitor C or RC to the diode. The purpose of this is mainly to suppress high-frequency oscillations, but its value must be determined through multiple tests, because if the selected value is not appropriate, it may be Bring counter-effects, so choose this method must be cautious.
3. it is most effective to connect with LDO filtering, but at the same time the cost is also the highest, and the power consumption will be relatively large.
4. Adding a level LC filter, LC filter on the power adapter ripple suppression will be not bad as well.