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VISHAY SPRAGUE
Tantalum Capacitors
Application Note
Low ESR Tantalum Capacitors Make a Difference
in Circuit Designs
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APPLICATION NOTE
Revision: 06-Sep-2019
1
Document Number: 40256
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By Charles Pothier
Low ESR tantalum capacitors can improve circuit power efficiency, reduce heat generation for the circuit, and increase low-term
reliability.
When choosing a capacitor for any application, there are a few key characteristics that must be understood in order to analyze
its suitability for the circuit. In a simple capacitor equivalent circuit model, there are three key characteristics that affect circuit
performance: capacitance, equivalent series resistance (ESR), and inductance. The magnitude of these elements - and how they
change over temperature, frequency, and applied voltage - are different for each capacitor technology.
In this application note, we will examine the ways in which ESR in tantalum capacitors affects circuit performance. ESR is the
sum of all of the purely resistive contributors to the capacitor's impedance. As such, it is the characteristic that creates losses
due to heating. It also affects the magnitude of charge and discharge currents as the capacitor does its work.
In a solid tantalum capacitor, the components that contribute to ESR are the resistivity of the:
• Solid electrolyte system (MnO
2
)
• Dielectric layer (Ta
2
O
5
)
• Terminations, lead frames, and other elements that provide connection to the PCB
Solid tantalum capacitor manufacturers can make improvements in physical design and materials that reduce the overall ESR
of the capacitor. These lower ESR capacitors will lead to reductions in heat generation within the capacitor, thus improving
overall circuit efficiency and long-term reliability. Reductions in ESR will also improve the capacitor's ability to supply higher
currents during charge and discharge cycles to improve circuit performance. Typical impedance (Z) and ESR data for a range
of popular values are shown in Table 1.
Two primary functions that tantalum capacitors are ideally suited for are bulk energy storage and waveform filtering.
TABLE 1 - TYPICAL IMPEDANCE (Z) AND ESR DATA FOR A RANGE OF POPULAR VALUES
10
100
1000
10000
0.01
0.1
1
0.1 1 10 100 1000
“D” Case
1st line
2nd line
2nd line
Impedance / ESR (Ω)
Frequency (kHz)
68 μF, 20 V
DC
470 μF, 4 V
DC
ESR
Impedance
10
100
1000
10000
0.01
0.1
1
0.1 1 10 100 1000
“D” Case
1st line
2nd line
2nd line
Impedance / ESR (Ω)
Frequency (kHz)
ESR
Impedance
220 μF, 10 V
DC
330 μF, 6.3 V
DC