FFLC31MA4427 Datasheet, PDF (9/9 Pages) AVX Corporation – Medium Power Film Capacitors

Medium Power Film Capacitors
FFLC
CALCULATION FORM
SPECIFICATION
Capacitance
Working voltage
Rms current
Frequency
Ripple voltage
Ambient temperature
Lifetime @ Uw,Irms and θamb
Parasitic inductance
Cooling conditions
C (μF)
Uw (V)
Irms (Arms)
f (Hz)
Ur (V)
θamb (°C)
hours
L (nH)
Your choice
PN
Capacitance
Rated voltage
Serial resistance
Thermal resistance between
hot spot and case
Thermal resistance between
case and ambient air
C (μF)
Un (V)
Rs (mΩ)
R_th1 (°C/W)
Rth2 (°C/W)
CALCULATIONS
Maximum ripple voltage
U_rmax = 0.2 U_n
U_rmax =
V
The maximum ripple voltage of the selected capacitor must be in any case higher than the ripple voltage of your application
Ratio Vw/Vn
ρ = Uw/Un
ρ=
Joule losses
P_j = R_sxI_rms²
P_j =
W
Dielectric losses
Pd = Qxtgδ0=Qx 2.10^-4
Pd =
W
Hot spot temperature
θHS = θamb+(Pj+Pd)x(Rth1+Rth2)
θHS =
°C
The hot spot temperature must be in any case lower than 85°C
LIFETIME EXPECTANCY VS HOT SPOT TEMPERATURE AND VOLTAGE
1.4
1.3
1.2
θ_HS = 55ºC
1.1
θ_HS = 70ºC
1.0
θ_HS = 85ºC
0.9
0.8
100
1,000
10,000
100,000
Lifetime Expectancy (hours)
1,000,000
Expected lifetime at hot spot calculated and U = U_w
50 ■ JUNE 2015