Version 4
SHEET 1 2036 932
WIRE -464 -656 -464 -720
WIRE -464 -528 -464 -576
WIRE -416 -720 -464 -720
WIRE -304 -720 -352 -720
WIRE -304 -656 -304 -720
WIRE -304 -528 -464 -528
WIRE -304 -528 -304 -576
WIRE -304 -496 -304 -528
WIRE -64 -720 -304 -720
WIRE 160 -720 16 -720
WIRE 160 -512 160 -720
FLAG -304 -496 0
FLAG -304 -720 in
FLAG 160 -512 0
SYMBOL current -304 -576 R180
WINDOW 0 -47 88 Left 0
WINDOW 3 -395 -19 Left 0
SYMATTR InstName I1
SYMATTR Value PULSE(0 2 0 0.1u 0.1u 100 200)
SYMBOL diode -352 -736 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName D2
SYMBOL voltage -464 -672 R0
SYMATTR InstName V1
SYMATTR Value 20
SYMBOL belfuse_C1Q_1A -32 -720 R0
SYMATTR InstName X1
TEXT -464 -864 Left 0 !.tran 0 10000m 1u
TEXT -464 -824 Left 0 !.options plotwinsize=0
TEXT -448 -1600 Left 0 ;FUSE MODEL\nHelmut Sennewald, 12.06.2005\n \nThermal resistance model \nincluding I^2*T behaviour \nand ambient temperature.\n \nVery high over current,  I > 10*In\nC_th1 mainly models I^2*t \nT_break = I^2T / (I_actual*I_actual)\n*\nMedium Over current, 2*In...10*In\nC_th2 \n \nLong time heating, 1.0*In...2*In\nC_th3
TEXT 0 -1248 Left 0 ;How to get the parameters?\n \n1. Set "Default"-table in Bcorr element!\n    I=Table(I(BIabs),  0, 0.0,  1e4, 1.0e4)\n2. Set TAU2=1m, TAU3=100\n*\n3. Set I=20*Inom, \n    Adjust TAU1 to achieve T_break={I^2*T}/(20*20)\n4. Adjust TAU2 for I=5*Inom\n5. Adjust TAU3 for I=2*Inom\n   It may be necessary to vary the ratio between R_TH2 and R_TH3\n   The sum of the ratios must be always 1.0\n6. Goto 3 and check/correct until you see no more improvement\n*\n7. Finally fit the table of the "Bcorr" element
TEXT 0 -1664 Left 0 ;The idea behind this model\n \nMeasured current:   Imeas,       \nAdjust it to improve the fit:   I = f(Imeas)      \nActual power dissipation of the fuse:   P=I^2*R(T) \nSteady state temperature depends on \n    power and thermal resistance:   T=Tamb+P*Rth    \nResistance depends on temperature:   R(T)=R0*(1+alpha*T)   \nDynamic behaviour:  current prop. T loads a RC combination. \nBreak(blow) condition:  If T>Tlimit -> break\n \nHint, the ambient temperature T_AMB can be passed to\nthe model, e.g. T_AMB=25.
TEXT -456 -920 Left 0 ;Watch V(in)