EEV107M035A9HAA Datasheet, PDF (9/16 Pages) Kemet Corporation – Surface Mount Aluminum Electrolytic Capacitors EEV Series, +105ºC

Surface Mount Aluminum Electrolytic Capacitors – EEV Series, +105ºC
• Capacitive reactance predominates at low frequencies
• With increasing frequency, capacitive reactance Xc = 1/ωC_o decreases until it reaches the order of magnitude of electrolyte
resistance R_e(A)
• At even higher frequencies, resistance of the electrolyte predominates: Z = R_e (A - B)
• When the capacitor’s resonance frequency is reached (ω₀), capacitive and inductive reactance mutually cancel each other
1/ωC_e = ωL, ω₀ = C√1/LCe
• Above this frequency, inductive reactance of the winding and its terminals (XL = Z = ωL) becomes effective and leads to an increase
in impedance
Generally speaking, it can be estimated that C_e ≈ 0.01 C_o.
Impedance as a function of frequency (sinusoidal waveform) for different temperature values can be represented as follows (typical
values):
Z (ohm)
1000
10 µF
100
-4 0°C
10
2 0°C
1
8 5°C
0.1
0.1
1
10
100
1000
10000
R_e is the most temperature-dependent component of an electrolytic capacitor equivalent c^Firc⁽u^Kit^H. E^zl⁾ectrolyte resistivity will decrease if
temperature rises.
In order to obtain a low impedance value throughout the temperature range, R_e must be as little as possible. However, R_e values
that are too low indicate a very aggressive electrolyte, resulting in a shorter life of the electrolytic capacitor at high temperatures. A
compromise must be reached.
Leakage Current (LC)
Due to the aluminum oxide layer that serves as a dielectric, a small current will continue to flow even after a DC voltage has been
applied for long periods. This current is called leakage current.
A high leakage current flows after applying voltage to the capacitor then decreases in a few minutes, e.g., after prolonged storage
without any applied voltage. In the course of continuous operation, the leakage current will decrease and reach an almost constant
value.
After a voltage-free storage the oxide layer may deteriorate, especially at high temperature. Since there are no leakage currents to
transport oxygen ions to the anode, the oxide layer is not regenerated. The result is that a higher than normal leakage current will flow
when voltage is applied after prolonged storage.
As the oxide layer is regenerated in use, the leakage current will gradually decrease to its normal level.
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A4002_EEV • 2/21/2014 9