Datasheet

11© KEMET Electronics Corporation • KEMET Tower • One East Broward Boulevard A4049_EDH • 4/23/2019
Fort Lauderdale, FL 33301 USA • 954-766-2800 • www.kemet.com
Surface Mount Aluminum Electrolytic Capacitors – EDH, +105°C
Impedance (Z) cont’d

C
o
R
e
L
C
e
0
.
1
1
1
0
1
0
0
1,000
10,000
0
.
1
1
1
0
1
0
0
1,000
Z
[
o
h
m
]
F
[
K
H
z
]
B
C
A
1
/
ω
ω
ω
ω
C
o
R
e
1
/
ω
ω
ω
ω
C
e
ω
L
• 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(ω
0
),capacitiveandinductivereactancemutuallycanceleachother
1/ωC
e
=ωL,ω
0
=1/SQR(LC
e
)
• 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):
0
.
1
1
1
0
1
0
0
1,000
10,000
0
.
1
1
1
0
1
0
0
1,000
Z
(
o
h
m
)
F
(
K
H
z
)
8
5
°
C
2
0
°
C
10 µF
-
4
0
°
C
R
e
isthemosttemperature-dependentcomponentofanelectrolyticcapacitorequivalentcircuit.Electrolyte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.