Kuidas lahendada müra lülitamine toide toide
Power off, small size, low cost, and high efficiency make it a great value.
However, its biggest drawback is high output noise due to high switching transients. It is this shortcoming that prevents them from being used in high-performance analog circuits mainly powered by linear regulators.
Siiski, it on olnud tõestatud et in palju rakendused a korralikult filtreeritud lülitamine muundur saab asendada a lineaarne regulaator to genereerida a madal müra võimsus toide.
Seega, it on vajalik to disain an optimeeritud ja summutatud mitmeastmeline filter to eliminate väljund müra of the switching power converter.
The example circuit in this article will use a boost converter, but the results can be directly applied to any DC-DC converter. Figure 1 shows the basic waveforms of a boost converter in constant current mode (CCM).
Joonis 1. Aluseline pinge ja vool lainekujud a võimendus muundur
The output filter is important for a boost topology, or any other topology with discontinuous current mode, because of the fast rise and fall times of the current in switch B. This result in parasitic inductance in the excitation switches, layout, and output kondensaatorid. The result is that in actual use, output waveform looks more like Figure 2 than Figure 1, even with good layout and ceramic output Kondensaatorid.
2. Tüüpiline mõõdetud lainekujud of a boost muundur in DCM
The switching ripple (switching frequency) due to changes in capdenator charge is very small compared to the undamped heling of the output switch, edas signed to output noise. Tüüpiliselt, this output noise ranges from 10 MHz to over 100 MHz, well beyond the the self-resonant frequency of most ceramic output kondensaatorid. Seega, adding extra mahtuvus does not do much for noise attesumatsioon.
The ADIsimPower design tool avoids this problem by using a linearization formula for component values (such as cost or size) to optimize before actually selecting components, and optimize the output after selecting actual components from a database of thousands of devices . But the level of complexity is unnecessary when start out with a design. Kasutamine the provided calculations, using a SIMPLIS simulator—such as the free ADIsimPE™—or spending some time at the lab bench, you can arrive at a satisfactory design with minimal effort.
