Base Theory Low ESR Tantalum Capacitors Make a Difference in Circuit Designs By Charles Pothier

Eltronicschool. - There are many electronic circuit design that use capacitor component in its design. Capacitor can be use as filter, couppling, and another function again. One kind of capacitor is tantalum capacitor that can be used in many different circuit design.

Two primary functions that tantalum capacitors are ideally suited for are bulk energy storage and waveform filtering.

In here we will discuss about base theory of capacitor specially in topic Low ESR Tantalum Capacitors Make a Difference in Circuit Designs that written By Charles Pothier. Base on him paper that 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:

1. Solid electrolyte system (MnO2)
2. Dielectric layer (Ta2O5)
3. 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. above