Analysis of frequency characteristics of chip tantalum capacitors

We know that every capacitor has its frequency characteristic, so what is the frequency characteristic of AVX tantalum capacitor? AVX tantalum capacitors decrease in effective capacitance as frequency increases until resonance is reached (usually between 0.5 and 5MHZ).

Taking the 220UF 10V specification of e-type tantalum capacitor of AVX chip as an example, shenzhen zongshengyuan technology co., ltd. will explain the frequency characteristic of tantalum capacitor and the temperature characteristic curve of AVX tantalum capacitor.

Temperature characteristics of AVX tantalum capacitors

The capacitance of tantalum capacitors varies with temperature. The change itself is a small degree dependent on the rated voltage and capacitance. As can be seen from the temperature curve below, the capacity of tantalum capacitor and niobium capacitor will increase with the increase of temperature within the working temperature range.

Tangent of loss Angle

This is a measurement of energy loss in capacitors. It is expressed as tan, is the power loss of the capacitor and its reactive power is divided into a set of specified sinusoidal voltage frequencies. The terms used are power factor, loss factor and dielectric loss. COS (90-) is the real power factor. Using the measurement to perform the measurement tan bridge provides a 0.5V RMS120HZ sinusoidal signal.

The relationship between dissipation and temperature

Typical curve of dissipation coefficient with temperature variation. These blocks are tantalum and OXICAP identical capacitors.

Tangent loss Angle (TAN) measured by a dissipation factor, expressed as a percentage. DF measurement is carried out to measure the bridge supply of a 0.5v RMS120HZ sinusoidal signal, harmonics and 2.2vdc.df values are temperature and frequency dependent.

Frequency dependence of dissipation factors

As the frequency increases the loss factor is shown in the typical curve of tantalum and OXICAP capacitors, which is the ratio of current to voltage at the specified frequency. Three factors contribute to the impedance of tantalum capacitors, the resistance capacitance of the semiconductor layer, the electrode and the inductance of the lead wire, and the inductance caused by high frequency becomes a limiting factor. The temperature and frequency behavior determine the impedance behavior of these three factors, the impedance Z impedance is at 25 degrees and 100KHZ.

Equivalent series resistance ESR of AVX tantalum capacitor

Resistance losses occur in all viable forms of capacitors. These are made up of several different mechanisms, including resistance elements and contacts, viscous forces within the medium and production bypasses of the defect current path. In order to express the effect of these losses on their capacitance ESR.

Impedance of AVX tantalum capacitors and frequency dependence of ESR

Both ESR and impedance increase with frequency, and bifurcated impedance becomes more important as an additional contribution at lower frequency values.

AVX tantalum capacitors have a limited capacity to withstand voltage and current surge, which is based on the common property of all electrolytic capacitors. A high enough electrical stress will pass through the dielectric, thus damaging the dielectric. For example, a 6-volt tantalum capacitor has an electric field of 167 kv/mm at its rated voltage. Therefore, it is important to ensure that the voltage of the entire capacitor terminal never exceeds the specified surge voltage rating. As a semiconductor for tantalum capacitor negative plate, manganese dioxide has self-healing ability. However, this low resistance is limited, and in the case of low impedance circuits, the capacitor may be broken by the surge current. Step-down capacitance increases component reliability. Rated voltage on the use of common trajectory, low impedance voltage tantalum capacitance in a circuit for quick charge or discharge, protect the resistance for 1 Ω/V, if not meet this requirement the tantalum capacitor step-down coefficient should be used as high as 70%, in this case, may need a higher voltage than as a single capacitance. Series A combinations shall be the equivalent capacitors used to increase the operating voltage.

For example, two 22UF25V series parts are equivalent to one 11UF50V part. Refers to the capacity in a short period of time after a minimum 330 HMS series resistance of the circuit (1 k Ω CECC countries) to withstand the highest voltage. The surge voltage can reach up to 10 times the limit voltage and up to 30 seconds in an hour under normal temperature. Surge voltage is only a reference parameter and cannot be used as the basis of circuit design. Capacitance should be charged and discharged regularly during normal operation. The value of surge voltage is different at different temperatures. When the temperature is 85 degrees and below, the classified voltage VC is equal to the rated voltage VR, and the surge voltage VS is 1.3 times of the rated voltage VR. At 85-125 degrees, the classified voltage VC is equal to 0.66 times the rated voltage VR, and the surge voltage VS is equal to 1.3 times the classified voltage VC.

Reverse voltage of tantalum capacitor

The reverse voltage of AVX tantalum capacitor is strictly limited as follows:

Rated dc operating voltage up to 10% at 1.0v 25 c

Rated dc working voltage up to 3% at 0.5v 85c

Rated dc working voltage up to 1% at 0.1v 125c

The reverse voltage values are based on the highest voltage values of tantalum capacitors at any time, and these limits are based on the assumption that the polarized light of tantalum capacitors will work in most correct directions. Their aim is to cover a small portion of an impressive waveform as a short-term reversal occurs during switching transient polarity. Continuous application of the reverse voltage will lead to polarization and increase leakage current. In situations where continuous reverse application voltages may occur two similar capacitors should be connected with a negative terminal tie-back configuration. In most cases this combination will have a nominal capacitance.

The superimposed alternating current voltage of tantalum capacitors (vr.m.s.) -- also known as ripple voltage

This is the maximum R.M.S. ac voltage that can be applied to a capacitor by superimposing a dc voltage.