What Is a Tantalum Capacitor?
A tantalum capacitor is a polarized capacitor using tantalum metal, offering high, stable capacitance in a small size. It's an alternative to the electrolytic in compact devices.
Properties
At the same capacitance it's smaller, more stable and has lower ESR than an electrolytic. Its capacitance changes little with temperature.
Difference From Electrolytic
| Property | Tantalum | Electrolytic |
|---|---|---|
| Size | Smaller | Larger |
| Stability | High | Medium |
| Overvoltage | Sensitive (short circuit) | More tolerant |
Polarity and Explosion Risk
A tantalum is also polarized and especially sensitive to inrush current/overvoltage; if the limit is exceeded it can short and catch fire. So a voltage margin (derating) is left.
Where Is It Used?
In phones, medical devices and space-limited boards, as stable filtering and an energy store.
Why Is Voltage Derating a Must?
Since a tantalum is sensitive to overvoltage and inrush current, for safe use it's run at usually 50% of its rated voltage. This margin significantly reduces the risk of short circuit and fire during unexpected voltage spikes. Also, placing a small series resistor at the input to limit the startup current protects its life.
Common Mistakes
- Leaving no voltage margin: running at 50% of the rated voltage is recommended.
- Reverse polarity: risk of short circuit and fire.
- High inrush current: if the inrush isn't limited, it can fail.
Frequently Asked Questions
Tantalum or electrolytic?+
Why does a tantalum need derating?+
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