DATA SHEET: CAPACITORS #2

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From: Paul Harden (pharden@aoc.nrao.edu)
Date: Fri Mar 10 1995 - 11:21:54 EST


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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