Datasheet

12© 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
Leakage Current (LC)
Duetothealuminumoxidelayerthatservesasadielectric,asmallcurrentwillcontinuetoflowevenafteraDCvoltagehas
beenappliedforlongperiods.Thiscurrentiscalledleakagecurrent.
Ahighleakagecurrentflowsafterapplyingvoltagetothecapacitorthendecreasesinafewminutes,forexample,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a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flow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.
Therelationshipbetweentheleakagecurrentandvoltageappliedatconstanttemperaturecanbeshownschematicallyas
follows:
I
V
R
V
F
V
V
S
Where:
V
F
= Forming voltage
Ifthislevelisexceeded,alargequantityofheatandgaswillbegeneratedandthecapacitorcouldbedamaged.
V
R
= Rated voltage
Thislevelrepresentsthetopofthelinearpartofthecurve.
V
S
= Surge voltage
ThisliesbetweenV
R
andV
F
.ThecapacitorcanbesubjectedtoV
S
forshortperiodsonly.
Electrolyticcapacitorsaresubjectedtoareformingprocessbeforeacceptancetesting.Thepurposeofthispreconditioning
istoensurethatthesameinitialconditionsaremaintainedwhencomparingdifferentproducts.
Ripple Current (RC)
Themaximumripplecurrentvaluedependson:
• Ambient temperature
 •Surfaceareaofthecapacitor(heatdissipationarea)
tanδorESR
 •Frequency
Thecapacitor’slifedependsonthethermalstress.