EMC Question of the Week: May 12, 2025
The yellow component in this figure is a
- ceramic capacitor
- tantalum capacitor
- TVS diode
- crystal oscillator
Answer
The correct answer is “b.” These yellow polarized capacitors often used for DC power bus decoupling are polymer electrolytic capacitors employing a tantalum oxide dielectric. They provide higher values of capacitance than the ceramic capacitors used for high-frequency decoupling. And, they have a smaller package size and lower equivalent series resistance (ESR) than standard electrolytic capacitors with similar nominal capacitance values.
Tantalum capacitors are widely used, but they are not appropriate for all applications. These capacitors can fail in the presence of voltage transients only slightly higher than their rated voltage. For this reason, they should only be used in situations where the DC bias voltage is well regulated, and the failure of a single capacitor does not pose an unacceptable risk.
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