DC Leakage Current is the current that flows

through the capacitor dielectric after a five minute

charging period at rated voltage. Leakage is meas-

ured at 25°C with full rated voltage applied to the

capacitor through a 1000 ohm resistor in series with

the capacitor.

DC Leakage Current does increase with tempera-

ture. The limits for 85°C @ Rated Voltage and

125°C are both 2 times the 25°C limit.

7.

Dissipation Factor (DF)

Refer to part number tables for maximum DF limits.

Dissipation factor is measured at 120 Hz, up to 1.0

volt rms maximum. Dissipation factor is the ratio of

the equivalent series resistance (ESR) to the capaci-

percentage. It is directly proportional to both capaci-

tance and frequency. Dissipation factor loses its

importance at higher frequencies, (above about 1

kHz), where impedance (Z) and equivalent series

resistance (ESR) are the normal parameters of con-

cern.

DF is also referred to as tan

δ or "loss tangent."

The "Quality Factor," "Q", is the reciprocal of DF.

8.

Equivalent Series Resistance (ESR) and

Impedance (Z)

The Equivalent Series Resistance (ESR) of the AO-

CAP is much lower than standard Tantalum caps

because the polymer cathode has much higher con-

ductivity. ESR is not a pure resistance, and it

decreases with increasing frequency.

Total impedance of the capacitor is the vector sum of

nance; above resonance total impedance is the vec-

To understand the many elements of a capacitor,

see Figure 3.

Figure 3 The Real Capacitor

A capacitor has a complex impedance consisting of

many series and parallel elements, each adding to

the complexity of the measurement system.

ESL - Represents inductance. In most instances it is

significant at the basic measurement frequencies of

120 and 1000 Hz.

ESR - Represents the ohmic resistance in series

with the capacitance. Lead attachment and capacitor

electrodes are contributing sources.

DF = X

c

= 2

πfCR

Where:

DF = Dissipation Factor

R

= Equivalent Series Resistance (Ohms)

Xc = Capacitive Reactance(Ohms)

f

= Frequency (Hertz)

C

= Capacitance (Farads)

R

ESR

δδ

θθ

Xc =

2

πfC

(Ohms)

Where:

f = frequency (Hertz)

C = capacitance (Farad)

1

Figure 2a Total Impedance of the Capacitor

Below Resonance

XL = 2πfL (Ohms)

Where:

f = frequency (Hertz)

L = inductance (Henries)

δδ

θθ

Z

Figure 2b Total Impedance of the Capacitor

Above Resonance

ESL

ESR

C

ESR

©KEMET Electronics Corporation, P.O. Box 5928, Greenville, S.C. 29606, (864) 963-6300

ALUMINUM ORGANIC CAPACITORS

Performance Characteristics

59