0
\$\begingroup\$

In the power supply design, there are always smaller value capacitors placed at the output.What is the main role played by these capacitors in the module? Check the screenshot attached and I am referring to C7.

schematic

simulate this circuit – Schematic created using CircuitLab

\$\endgroup\$
  • \$\begingroup\$ Related but not fully duplicate: electronics.stackexchange.com/questions/320363/… \$\endgroup\$ – winny Feb 1 at 8:44
  • 1
    \$\begingroup\$ With smaller capacitors, you can create a mechanically-smaller loop, and reduce the inductance (perhaps greatly).This reduces the stored energy in a parasitic path, and reduces the amplitude of parasitic ringing voltage. \$\endgroup\$ – analogsystemsrf Feb 1 at 15:13
  • 1
    \$\begingroup\$ overly-short explanation: one is built for speed (little one), the other is for power (big one). \$\endgroup\$ – dandavis Feb 1 at 20:24
5
\$\begingroup\$

That is done because the 100 uF capacitor isn't very "good" / doesn't work very well at higher frequencies. The 100 nF is much better at those frequencies, but has a smaller value so does not work for lower frequencies. The 100 uF capacitor takes care of those lower frequencies.

By using these two in parallel we create a "better" capacitor that works at both low and high frequencies.

It is explained in more detail by Dave from the EEVBlog in this video.

\$\endgroup\$

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Not the answer you're looking for? Browse other questions tagged or ask your own question.