Can Tantalum Capacitors Replace MLCC?

灞波儿奔

Can Tantalum Capacitors Replace MLCC? [Copy link]

Lately, it has become increasingly difficult to find the right MLCC capacitors. In the long run, manufacturers can solve this problem by adding production lines. However, this is still a long way to go for many customers who need these materials urgently at the moment. When talking with product managers, we discussed the possibility of transitioning some customers from MLCC capacitors to tantalum capacitors. Although it was not the most popular suggestion, we did get some positive feedback, and Wilmer Companioni from Kemet had some suggestions for customers to consider. Below is a slideshow he created for the Kemet line of KO-CAP (organic polymer capacitors).
　　

　　If you are considering replacing MLCC capacitors with tantalum capacitors, you need to pay attention to several key parameters listed by Wilmar on this chart. I will summarize them below.
　　Capacitance Value
　　Tantalum capacitors tend to have higher capacitance values than MLCC capacitors in the same package size. As of the time of this article, the smallest capacitance value of Digi-Key capacitors is 0.47uF. The above chart shows 680nF because this is the smallest capacitance value currently available in the KO series. If you need a capacitance value lower than this, it is not recommended to use tantalum capacitors. One advantage of tantalum capacitors is that one tantalum capacitor can replace a group of MLCC capacitors, saving cost and space.
　　Voltage
　　When using tantalum capacitors, there are some restrictions on the voltage. When the voltage exceeds 35V, many tantalum capacitors are considered high voltage. This means that if you are operating at a voltage greater than 50V, then replacing MLCC with tantalum capacitors may not be a viable solution.
　　Equivalent Series Resistance
　　MLCCs are generally rated lower than their equivalent tantalum counterparts in terms of equivalent series resistance. Now there are tantalum capacitors with lower ESR, but if ESR is a higher priority for you, then you may have difficulty transitioning from MLCC capacitors to tantalum capacitors.
　　Frequency
　　When looking at tantalum capacitors, you need to pay attention to their self-resonant frequency. If you operate at a switching frequency higher than 1MHz, you may exceed the upper limit of tantalum capacitors.
　　Reverse Bias Voltage
　　Tantalum capacitors are polarized capacitors and therefore cannot withstand reverse bias voltage. If you want to place the capacitor in a position where reverse bias may exist or need to withstand reverse bias, tantalum capacitors are not suitable. Final conclusion: From this, it can be seen that replacement capacitors are possible, although sometimes unavailable or impractical. If you are in the dilemma of lacking MLCCs and want to find a solution, then this article can provide you with some reference.