be 35 K to 2.5 MOhms depending on voltage -

ceramics and in film capacitors.

absorption and molecular polarization. It becomes

very significant in high frequency measurements and

applications. Its value varies with frequency.

aluminum capacitor.

according to its equation. There is unavoidable

inductance as well as resistance in all capacitors,

and at some point in frequency, the reactance ceas-

es to be capacitive and becomes inductive. This fre-

quency is call the self-resonant point.

Figure 4 compares the frequency response of an

AO-CAP to a Tantalum chip. Maximum limits for 100

kHz ESR are listed in the part number tables for

each series.

Figure 4.

9. AC Power Dissipation

Power dissipation is a function of capacitor size and

materials. Maximum power ratings have been estab-

lished for all case sizes to prevent overheating. In

actual use, the capacitor's ability to dissipate the

heat generated at any given power level may be

affected by a variety of circuit factors. These include

board density, pad size, heat sinks and air circulation.

Power capability is determined based on a 20°C tem-

perature rise. A higher temperature rise and therefore

higher power capability is allowable as long as the

ambient temperature plus temperature rise due to rip-

ple current does not exceed the rated temperature of

the part.

Table 3 - AO Capacitor Power Dissipation Ratings

10. Ripple Current/Voltage

Permissible AC ripple voltage and current are related

to equivalent series resistance (ESR) and power dis-

sipation capability.

Permissible ripple current which may be applied

is limited by two criteria:

a. The resulting voltage across the capacitor with the

summation of DC bias and peak voltage of the

AC portion must not exceed the rated voltage of

the capacitor.

b. The negative peak AC voltage, in combination

with bias voltage, if any, must not exceed the per-

missible reverse voltage ratings presented in

Section 5.

Actual power dissipated may be calculated from the

following:

Where:

I = rms ripple current (Amperes)

E = rms ripple voltage (Volts)

P = power (Watts)

Z = impedance at specified frequency (ohms)

R = ESR(Ohms)

Using P max from Table 3, maximum allowable rms

ripple current or voltage may be determined as fol-

lows:

Where:

+20°C

Refer to part number listings for permittable Arms

limits.

Case Code

Maximum Power Dissipation mWatts

@ +25°C with 20° Temperature Rise

KEMET

EIA

V

7343-20

270

D

7343-31

250

X

7343-43

225

Z

ESR

R

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

ALUMINUM ORGANIC CAPACITORS

Performance Characteristics

60