Aluminum Polymer Capacitors

Last Ask-Away-Friday, I received the following question:

“How do you think of aluminium-polymer capacitors?”

These relatively new type of capacitors turn out to be very neat in practice. I’ve designed several power supplies with them (fly-back, buck, boost and buck-boost) en they yield excellent results. They lend themselves very well for filters with low corner frequencies.

The advantages of aluminium-polymer capacitors are a low ESR, the associated high ripple current and a long lifetime. The biggest disadvantage in my opinion is the high leakage current, which makes these capacitors unsuitable for low-power designs. When designing filters, the leakage current must be factored in as well.

In conclusion, the aluminium-polymer capacitors are not the perfect all-rounders, but they are a useful expansion to the many solutions that electronics designers can choose from.

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