Capacitor-input or choke-input filter?

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In summary, the main difference between capacitor-input and choke-input filters for power supplies is their use and purpose. Capacitor-input filters are used to keep switching noise out of the AC mains, while choke-input filters are used to prevent feed-forward stability issues. Examples of where these filters may be used include AC mains connected switching power supplies and between the power source and input of a switching power supply.
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Capacitor-input or choke-input filter for power supplies?

Whats the difference and when to use them?
 
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Pagedown said:
Capacitor-input or choke-input filter for power supplies?

Whats the difference and when to use them?

Can you give some examples?

For AC Mains connected switching power supplies, you will generally have a line filter that has both chokes and caps in it. One of the main tasks of the line filter is to keep the switching noise of the power supply out of the AC Mains, in order to meet conducted emissions limits set by the FCC and other governmental agencies.

Depeding on the power source, you may put filtering between the power source and the input to a switching power supply, to help prevent feed-forward stability issues that could be caused by the input noise.
 

1. What is a capacitor-input filter?

A capacitor-input filter is a type of electronic filter used to smooth out the output of a rectifier circuit. It consists of a capacitor connected in parallel with the load resistor, which helps to filter out any ripple or AC component from the rectified output.

2. What is a choke-input filter?

A choke-input filter is also a type of electronic filter used to smooth out the output of a rectifier circuit. It consists of a choke (inductor) connected in series with the load resistor, which helps to filter out any ripple or AC component from the rectified output.

3. What is the difference between a capacitor-input and choke-input filter?

The main difference between these two filters is the location of the filter element (capacitor or choke) in the circuit. In a capacitor-input filter, the capacitor is connected in parallel with the load resistor, while in a choke-input filter, the choke is connected in series with the load resistor. This difference can affect the amount of ripple reduction and the output voltage of the filter.

4. When should I use a capacitor-input filter and when should I use a choke-input filter?

The choice between these two filters depends on the specific application and requirements. A capacitor-input filter is more commonly used for low-power applications, where the output voltage needs to be closely regulated. A choke-input filter, on the other hand, is more suitable for high-power applications, where a higher output voltage and better ripple reduction are desired.

5. What are the advantages and disadvantages of using a capacitor-input or choke-input filter?

The main advantage of using either of these filters is that they help to reduce the ripple or AC component from the rectified output, resulting in a smoother DC output. However, a capacitor-input filter has the disadvantage of having a lower output voltage and may require a larger capacitor for better ripple reduction. A choke-input filter, on the other hand, requires a larger choke and may have a higher output voltage. Moreover, it also has the disadvantage of having a higher voltage drop across the choke, resulting in lower efficiency.

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