
KEMET Electronics Corporation, P.O. Box 5928, Greenville, S.C. 29606, (864) 963-6300
COMPONENT PERFORMANCE CHARACTERISTICS
DC Leakage current does increase with tempera-
ture. The limits for 85oC @ Rated Voltage and
105oC @ 0.8 x Rated Voltage are both 10 times
the 25oC limit.
7. Surge Current Capability
Certain applications may induce heavy surge cur-
rents when circuit impedance is very low (<0.1
ohm per volt). Driving inductance may also cause
voltage ringing. Surge currents may appear as
transients during turn-on of equipment.
The KO-CAP has a very high tolerance for surge
current. And although the failure mechanism is a
short circuit, they do not ignite as may occur with
standard tantalums in such applications.
The KO-CAP series receives 100% screening for
surge current in our production process.
Capacitors are surged 4 times at full rated voltage
applied through a total circuit resistance of <0.5
ohms. Failures are removed during subsequent
electrical testing.
8. 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, and up to 2.5 volts DC maxi-
mum at +25oC. The application of DC bias causes
a small reduction in DF, about 0.2% when full
rated voltage is applied. DF increases with
increasing frequency.
Dissipation factor is the ratio of the equivalent
series resistance (ESR) to the capacitive reac-
tance, (X
C
) and is usually expressed as a percent-
age. It is directly proportional to both capacitance
and frequency. Dissipation factor loses its impor-
tance at higher frequencies, (above about 1 kHz),
where impedance (Z) and equivalent series resis-
tance (ESR) are the normal parameters of concern.
DF = R = 2 f CR
DF= Dissipation Factor
X
C
R= Equivalent Series
Resistance (Ohms)
X
C
= Capacitive Reactance
(Ohms)
f= Frequency (Hertz)
C= Series Capacitance
(Farads)
DF is also referred to as tan
The “Quality Factor,” “Q,” is the reciprocal of DF.
or “l(fā)oss tangent.”
9. Equivalent Series Resistance (ESR) and
Impedance (Z)
The Equivalent Series Resistance (ESR) of the KO-
CAP is much lower than standard Tantalum caps
because the polymer cathode has much higher
conductivity. ESR is not a pure resistance, and it
decreases with increasing frequency.
Total impedance of the capacitor is the vector
sum of capacitive reactance (X
C
) and ESR, below
resonance; above resonance total impedance is
the vector sum of inductive reactance (X
L
) and
ESR.
X
C
= 1 ohm
2 fC
where:
f = frequency, Hertz
C = capacitance, Farad
FIGURE 2a
Total Impedance of the Capacitor Below
Resonance
X
L
= 2 fL
where:
f = frequency, Hertz
L = inductance, Henries
FIGURE 2b Total Impedance of the Capacitor Above
Resonance
To understand the many elements of a capaci-
tor, see Figure 3.
CONDUCTIVE POLYMER CHIP CAPACITORS
44