Would there be any disadvantage (other than a high component count) to using seven 470 μF, 16 V electrolytic capacitors instead of one 3300 μF, 16 V capacitor to smooth power supply ripple?
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1\$\begingroup\$ If the ESR is also suitable, that's perfectly fine. \$\endgroup\$– Tim WilliamsCommented Jan 1, 2023 at 1:53
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\$\begingroup\$ For a number of reasons, we use a variety of cap values and types for output filtering. A typical PS might have (15) 2.2 uF ceramics, (4) 330 uF tantalums, and (4) 1 uF ceramics. \$\endgroup\$– SteveShCommented Jan 1, 2023 at 2:29
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1\$\begingroup\$ It is often necessary to do this to get adequate ripple current capacity in the output capacitors, or to reduce the per cap ripple current to reduce heating and improve capacitor life. From the previous comment, I'm note sure what the advantage of using both 1uF and 2.2uF ceramics would be, but I often use a few very low ESR ceramic caps closest to the inductor (for a buck converter) and an electrolytic a little further away. The Electrolytic helps prevent ringing that can be contributed to by the low ESR ceramics. \$\endgroup\$– Dean FranksCommented Jan 1, 2023 at 3:13
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2 Answers
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In general, the capacitor selection depends on the power supply impedance vs frequency that you must achieve.
In the specific case of 1 large electrolytic vs. several smaller ones, it is usually a concern of construction volume shape and BOM availability. Ripple current capacity and ESR tend to be rather similar, and ESL is usually not a concern for the frequency range addressed with the electrolytic capacitors.
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It depends on the type of power supply and what the power supply requires from the capacitor to function properly and where in the power supply the capacitor is and what is the function of the capacitor.
If the ESR and ESL of the combined 7 caps are much lower compared to single cap then a regulator may not work properly if the ESR and ESL of output capacitor go out of stable range.
If the single cap was already a low ESR one then there might not be a huge difference.
7 caps may take more space and cost more which may be a disadvantage.
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\$\begingroup\$ In this case it is a bipolar 12VDC 1A power supply for common eurorack synthesizer modules. Nothing exotic. The stock circuit calls for 3-3300uF capacitors on each side, but I have literally hundreds of 470uF capacitors here that I'm not using. \$\endgroup\$ Commented Jan 2, 2023 at 1:45