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Capacitors Application Edward Chen. All capacitors utilize the same basic mechanism in their structure. Dielectric. Electrode Plates. The value of a capacitor is measured in farads. For 1 farad. of capacitance, 1 coulomb of charge is stored on the plates,. when 1 volt of force is applied.
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All capacitors utilize the same basicmechanism in their structure Dielectric Electrode Plates The value of a capacitor is measured in farads. For 1 farad of capacitance, 1 coulomb of charge is stored on the plates, when 1 volt of force is applied. 1 farad = 1 coulomb / 1 volt 1 coulomb represents ~ 6 x 1019 electrons 2
X ESL - Inductive Reactance (X ) L opposes Capacitive Reactance ESR X L 0 Z X Impedance is now a XC factor of resultant 2 2 Z = (X -X ) + ESR C L 3
XL increasing self-resonant frequency. Self-Resonance XC decreasing Reactance Frequency The frequency at which XC = XL is the self-resonant frequency. At this frequency, XC=-XL, or zero, and the impedance is equal to the ESR. Prior to this frequency, component behaves as capacitor; after this frequency, component behaves as inductor. 5
Capacitor Application • Decoupling • Coupling • Filtering • Timing/Wave-shaping
Decoupling Load (ex.IC) Power Supply Vin Vout Vin Vout Function: Absorb the voltage change (noise). Suitable Cap: Tan Cap, KO Cap, MLCC, Al E Cap
Coupling Function: Remove the DC voltage of A circuit and Transmit the exchange voltage to B circuit. (Allow an AC signal pass, but stop DC.) Suitable Capacitors: Tan Cap, MLCC Ex. Horn.
Filtering • Function: • Rectified AC smoothing • Frequency selective filtering • Suitable Cap: KO, Tan Cap, Hi C/V MLCC, Al E Cap
Timing / Wave-shaping Function: Timer Circuit (RC Timer). Suitable Cap: MLCC, KO Cap.