© pichetw dreamstime.com_hand pushing information button on touch screen General | September 14, 2016

What can a different capacitor technology do for you?

Today's electronic design often doesn't utilises the available capacitor technologies for downsizing or performance improvement. It rather copies circuits or parts of older designs (grandfather design) even if other parts of the application have been electrically updated, writes Michael Freitag, BDM Director at component manufacturer Kemet.
Different and further developed capacitor technologies have an influence on the output performance of a DC/DC converter, or SMPS, through their parasitic effects over various ambient conditions and lifetime. A capacitor has an important impact on the stability and performance of an application.

When it comes to application notes or reference designs, aluminium electrolytic or low ESR Tantalum Capacitors are often recommended as input or output capacitors for decoupling and smoothing. The latest recommendations even propose the use of low ESR polymer technologies. High Capacitive MLCC's are recommended as well, especially when switching frequencies are increasing above 500kHz and storing the energy temporarily is shorter than with lower frequencies.
Considering that the ripple voltage and ESR's would be the same, a 200kHz application needs 200uF, while a 100kHz application would need twice as much capacity. The use of MLCC's becomes more visible with students or young design engineers, as data sheets look very promising.

“From discussions with engineers and real case examples we are confident that a lot of the behaviour of a capacitor is not known and engineers focus more on active components than in general on passives. As these passive components of an application are equally important the application example should lead to a conclusion of best practices for different application environments and should show the influences on the effective capacity”, Michael Freitag explains, when talking about his upcoming presentation during TEC Lund 2016.

Such complex behaviours cannot be expressed with a brief data sheet anymore and therefore modern simulation apps are available free of charge in the internet. This enables to query a component behaviour at its application environment to be used for.

To utilise the board space and the available commercial resources best a general knowledge of the technologies is a must to perform a continues downsizing with stable performance and long term stability.

Want to attend Michael Freitag's seminar on the comparison of capacitor technology? Register here for free.


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