EXV226M6R3A9BAA Datasheet, PDF (12/18 Pages) Kemet Corporation – Surface Mount Aluminum Electrolytic Capacitors

Surface Mount Aluminum Electrolytic Capacitors – EXV Series, +105°C
Leakage Current (LC) cont’d
As the oxide layer is regenerated in use, the leakage current will
gradually decrease to its normal level.
I
The relationship between the leakage current and voltage applied
at constant temperature can be shown schematically as follows:
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_R V_S
V_F
V
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.
Frequency Dependence of the Ripple Current
ESR and, thus, the tan δ depend on the frequency of the applied voltage. This indicates that the allowed ripple current is also
a function of the frequency.
Temperature Dependence of the Ripple Current
The data sheet specifies maximum ripple current at the upper category temperature for each capacitor.
Expected Life Calculation
Expected life depends on operating temperature according
to the following formula: L = Lo x 2 ^(To-T)/10
Where:
L: Expected life
Lo: Load life at maximum permissible operating
temperature
T: Actual operating temperature
To: Maximum permissible operating temperature
This formula is applicable between 40°C and To.
Expected Life Calculation Chart
Expected life (h)
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