Capacitor Selection - Suggestions for 100kHz Low ESR Decoupling

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Discussion Overview

The discussion revolves around selecting a suitable capacitor for decoupling in a circuit operating at a 100kHz switching frequency. Participants are exploring specifications for a capacitor that can handle a current ripple of about 1A while maintaining low equivalent series resistance (ESR). The circuit operates at 10V DC with an output current of 50A.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Exploratory

Main Points Raised

  • One participant requests suggestions for a capacitor suitable for decoupling at 100kHz with low ESR and a current ripple of 1A.
  • Another participant questions the presence of ripple current in a 10V DC supply and asks for a schematic to better understand the application.
  • A different participant emphasizes that all decoupling capacitors will experience ripple current, suggesting that if there is no ripple, the capacitor is unnecessary.
  • One participant recommends consulting a DigiKey catalog or website for capacitor selections specifically designed for switch mode power supplies.
  • There is a request for more information about the capacitor options already considered and the reasons for dissatisfaction with those options.

Areas of Agreement / Disagreement

Participants express differing views on the nature of ripple current in decoupling capacitors, with some questioning its presence in the given circuit configuration. The discussion remains unresolved regarding the specific capacitor selection and the implications of ripple current.

Contextual Notes

There are limitations in the discussion regarding the assumptions about ripple current and the specific application details that may affect capacitor selection. The schematic provided is not detailed enough to fully assess the circuit's requirements.

deen25
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capacitor selection...

Hey,

I'm having a bit of trouble selecting a capacitor and I just want to know if anyones got any suggestions ?...

I need a capacitor for decoupling...that would be suitable at 100kHz switching frequency..withstanding a current ripple of about 1A with a low ESR...this is required for decoupling. The circuit is supplied with 10V dc producing an output current of 50A.

has anyone got any suggestions or specifications you have already worked with ?cheers!
 
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deen25 said:
Hey,

I'm having a bit of trouble selecting a capacitor and I just want to know if anyones got any suggestions ?...

I need a capacitor for decoupling...that would be suitable at 100kHz switching frequency..withstanding a current ripple of about 1A with a low ESR...this is required for decoupling. The circuit is supplied with 10V dc producing an output current of 50A.

has anyone got any suggestions or specifications you have already worked with ?


cheers!

If it's supplied with 10Vdc, why is there ripple current? Is this part of your synchronous Buck DC-DC circuit? Can you show us the schematic for the application of this capacitor -- that would help us help you understand your choices.
 


hey...

I just drew this simple schematic now. It somewhat shows what the entire cct will look like..

hope this helps...

cheers!
 

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deen25 said:
hey...

I just drew this simple schematic now. It somewhat shows what the entire cct will look like..

hope this helps...

cheers!

What kind of capacitor options have you looked at so far? Why were you not happy with them? Tell us what work you have done in selecting this capacitor, other than just asking us about it.
 


Berkeman, ANY decoupling capacitor will have ripple current. If it doesn't have ripple current then it doesn't need to be there.
-
I believe the main thing you are looking for would be a low ESR/ESL cap. Grab a DigiKey catalog or go to the web-site. I believe they have selections for capacitors used specifically in switch mode power supplies.
 

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