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DATA SHEET de NA5N: CAPACITORS (part 2 of 2)

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Contents: SELECTION AND ORDERING GUIDE

DEFINITION OF TERMS

STANDARD VALUES OF CERAMIC/FILM CAPS

**************** SELECTION GUIDE *******************

(PRINCIPAL CHARACTERISTICS OF MAJOR CAPACITOR TYPES)

To compare characteristics between the major types

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CHARACTERISTIC CERAMICS POLYESTER POLY- POLY-

(X7R's) FILM CARBONATE PROPYLENE TANTALUM

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Capacitance range 10p-1uF .001-15uF .001-22uF .001-30uF .01-1000uF

Typical tolerance +/-20% +/-20% +/-10% +/-10% +/-5%

Voltage range 50-200v 50v-15kv 30-600v 100-800v 6-125v

Temperature range -55,+125 -65,+150 -65,+125 -65,+105 -55,+125

Temp. Coefficient +/-15% +/-15% +/-2% +/-2% +/-8%

Insulation Resistance

for <1uF, Megs/uF 10**4 10**4 10**5 10**7 70M ohms

for >1uF, Megs/uF 10**4 10**3 10**5 10**5 10M ohms

Dissipation factor

at 1KHz 2.5% 1.0% 0.3% 0.1% 8-24%

Dielectric Absorption 2.5% 0.5% 0.35% 0.05% na

Stability (1000hrs) 10% 10% 5% 3% 10%

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Design Considerations:

-Physical size 1 4 5 8 3

small moderate large largest moderate

-Cost factor 1 1 3-5 2-3 3

low low high moderate moderate

-Stability moderate moderate excellent excellent moderate

-Temp. stability poor poor excellent excellent moderate

-Freq. usage DC-low DC-low HF-VHF HF-VHF DC-low

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REFERENCES: Mallory Electronic Components Catalog

Sprague Film Capacitor Catalog

Sprague Capacitor Designers Guide for Engineers

MuRata/Erie Ceramic Capacitor Catalog

DEFINITIONS:

*CAPACITANCE TOLERANCE is the maximum deviation between the nominal value

(as marked on the capacitor) and the actual capacitance.

*WORKING VOLTAGE is the nominal continuous voltage which may be applied

without altering any characteristics. (Usually the max. applied volt.

without causing arcing/damage is the WVDC x 200%).

*TEMPERATURE COEFFICIENT (TC) is the change in capacitance per degree C.

A NEGATIVE coefficient is a REDUCTION in C as the temp. INCREASES.

*STABILITY (aging) is the change in capacitance over time, usually spec'd

at 1000hrs. Aging decreases logarithmically and thus the majority of

capacitance change due to aging occurs within the first 1000 hours.

*DISSIPATION FACTOR (DF) is the ratio of energy dissipated to the energy

stored in the capacitor. The DF is frequency sensitive and is usually

specified at a given frequency.

*QUALITY FACTOR (Q) is the ratio of energy stored to the energy dissi-

pated, or the inverse of DF. Also specified at a given frequency.

(Usually the dissipation factor OR the Q is specified, not both)

*DIELECTRIC ABSORPTION is the amount of energy dissipated in the capacitor

due to losses in the dielectric.

NOTE: The importance of these dissipation factors is what percentage of

the power (current and voltage) applied to the capacitor will be LOST

due to the dielectric and electrode resistance. This loss is primarily

converted into HEAT which will 1) change the capacitance of the device

depending upon its temperature coefficient, and 2) can cause damage to

the capacitor if its ratings are exceeded. At RF frequencies, the power

dissipated is the PEAK-TO-PEAK values, which can be large!

*INSULATION RESISTANCE (IR) is the DC resistance of the capacitor measured

across the terminals. It is a function of the resistance in the metal

electrodes and the resistance losses of the dielectric. Thus, the IR

will be lower for higher values of C (since it consists of more metal

and dielectric materials for higher capacitances).

*EQUIVALENT SERIES RESISTANCE (ESR) is the sum of the electrode resistance

plus the losses due to the dielectric. Dielectric losses are REACTIVE

since losses are frequency sensitive. ESR represents the "real" part of

the reactance (of the form "R+j").

******** STANDARD VALUES OF CERAMIC AND FILM CAPACITORS TO 1uF *********

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10pF 100pF .001uF .01uF .10uF Not all standard values are

15 150 .0015 .015 .15 available in certain families of

22 220 .0022 .022 .22 capacitors or for all voltage

27 270 .0027 .027 .27 ratings. Some manufacturers

33 330 .0033 .033 .33 also have additional values.

47pF 470pF .0047uF .047uF .47uF

56 560 .0056 .056 .56 Always specify the tolerance

68 680 .0068 .068 .68 desired, otherwise the highest

75 750 .0075 .075 .75 (worst) tolerance will be

82pF 820pF .0082uF .082uF .82uF assumed!

1.0uF

-------------------------------------- Common tolerance codes:

-J 5%

And, just a reminder: -K 10%

-L 15%

******* ******* -M 20%

* CAP * -----* CAP *-----

******* ******* *******

| | * CAP *-------

| | RADIAL LEADS *******

AXIAL LEADS BROKEN LEAD

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GL de Paul NA5N (pharden@nrao.edu)

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