Version 4
SHEET 1 4144 2708
WIRE 1968 -352 1840 -352
WIRE 1840 -304 1840 -352
WIRE 1968 -304 1968 -352
WIRE 1840 -176 1840 -224
WIRE 1968 -176 1968 -224
WIRE 1968 -176 1840 -176
WIRE 1840 -160 1840 -176
WIRE 1648 544 1520 544
WIRE 1520 592 1520 544
WIRE 1648 592 1648 544
WIRE 1520 720 1520 672
WIRE 1648 720 1648 672
WIRE 1648 720 1520 720
WIRE 1520 736 1520 720
FLAG 1840 -160 0
FLAG 1968 -352 ntc_BTH
FLAG 1520 736 0
FLAG 1648 544 ntc_B
SYMBOL current 1840 -224 M180
WINDOW 0 24 88 Left 0
WINDOW 3 30 -71 Left 0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName I8
SYMATTR Value PULSE(1m 0.1m 1 1u 1u 50 100)
SYMBOL current 1520 672 R180
WINDOW 0 24 88 Left 0
WINDOW 3 24 0 Left 0
SYMATTR InstName I1
SYMATTR Value 1
SYMBOL Miscel\\ResNoLin 1952 -320 R0
WINDOW 3 47 92 Left 0
WINDOW 123 48 119 Left 0
SYMATTR InstName R7
SYMATTR Value R0=10K B=3988
SYMATTR SpiceModel NTC_BTH
SYMATTR Value2 RTH=667  TAU=15
SYMATTR SpiceLine Tamb=Temp
SYMBOL Miscel\\ResNoLin 1632 576 R0
WINDOW 0 50 38 Left 0
WINDOW 38 86 67 Center 0
SYMATTR InstName R1
SYMATTR Value R0=10K B=3988
SYMATTR SpiceModel NTC_B
TEXT 1808 -536 Left 0 ;.STEP TEMP LIST  17  27 37 47
TEXT 1816 -576 Left 0 ;.OP
TEXT 1800 -640 Left 0 !.STEP TEMP  0 50 10
TEXT 2192 -648 Left 0 !.OPTIONS TNOM={T0}
TEXT 2208 -600 Left 0 !.PARAM R0=10000\n*.PARAM B=3988\n.PARAM TK=273.15\n.PARAM T0=25
TEXT 920 -632 Left 0 ;Dynamic Model for the NTC Thermistor in LTSPICE      \n-------------------------------------------------------------------------------\n 7/30/2004   Helmut Sennewald\nHint: The unit Ohm can be achieved on the y-axis if V(node)/1A is plotted.\n \ndT=TEMP-T0\nTEMP = T0 + dT\nT = TEMP+TK\nT0 is 27 degree for SPICE. It can be overwritten with e.g. ".OPTIONS TNOM=25".\nTK is 273.15 degree.\nR0 is resistance at a defined temperature, mostly 25 degree for NTC-thermistors.\n \n \nExponential temperature dependence\n-----------------------------------------------------------\nThis is a very common formula used for NTC thermistors.\nB is a material constant, e.g. B=3988\nB = T1*T2/(T2-T1)*ln(R1/R2)      R1, R2 is resistance at T1, T2\nR0 is resistance at T1 .\n \nFormula:  R = R0*exp(B*( 1/(TEMP+TK) - 1/(T0+TK) ))\nT = B/( ln(R/R0)+B/(T0+TK) )\nExample:  NTC with B=3988\n.PARAM R0=10000\n.PARAM B=3988\n.PARAM TK=273.15\n.PARAM T0=25\n*R1 n1 n2 {R0*exp(B*( 1/(TEMP+TK) - 1/(TNOM+TK) ))}\nReplace resistor R1 by a voltage controlled current source B1(Bi-source)\nB1 n1 n2  I=V(n1,n2)/{R0*exp(3988*(1/(TEMP+TK)-1/(T0+TK)))}\n \nThermal model for self heating\n------------------------------------------------\nThe current through the thermistor rises the thermistor's temperature.\ndTth =  P * Rth\nRth is the thermal resistance in degree/Watt \nRth = 1/delta_th in the EPCOS datasheet\nCth = TAU/Rth is the time constant\nPtherm = V*V/Rtherm \nV is the voltage acroos the thermistor.
TEXT 1808 -88 Left 0 !.SUBCKT NTC_BTH 1 2  R0={R0} B={B} RTH={RTH} TAU={TAU} \n* R0 resistance at 25degree\n* B material constant\n* Rth thermal resistance in degree/Watt\n* TAU time constant \n*.PARAM R0=10000\n*.PARAM B=3988\n.PARAM TK=273.15\n.PARAM T0=25\n* Resistor model\nRP 1 2 1G\nB1 1 2  I=V(1,2)/{R0*exp(B*(1/(V(3)+TEMP+TK)-1/(T0+TK)))}\n* Thermal model\n*V(3) is dT = Tntc-Tamb\nRTH 3 0  {RTH}\nCTH 3 0 {TAU/RTH}\nBTH 0 3  I=V(1,2)*V(1,2)/{R0*exp(B*(1/(V(3)+TAMB+TK)-1/(T0+TK)))}\n.ENDS
TEXT 1840 -408 Left 0 ;NTC 10k, B=3988  with self heating
TEXT 1808 -608 Left 0 !.TRAN 200
TEXT 2624 -648 Left 0 ;EPCOS Miniature Sensor  S861 (B57861)\ndelta_th=1.5mW/K  tau_c=15s  Cth=22.5mJ/K\nRT-Curve Number 8016\nB25/100 = 3988K   2-points: 25, 100degree\nSteinhart-Hart: 3-points: 0, 25, 100degree\nA=1.125293571e-3\nB=2.34714773e-4\nC=8.56501894e-8\n \n \n   T (°C)    RT/R25   (%/K)\n   -55.0,    96.30  ,  7.4\n   -50.0,    67.01  ,  7.2\n   -45.0,    47.17  ,  6.9\n   -40.0,    33.65  ,  6.7\n   -35.0,    24.26  ,  6.4\n   -30.0,    17.70  ,  6.2\n   -25.0,    13.04  ,  6.0\n   -20.0,    9.707  ,  5.8\n   -15.0,    7.293  ,  5.6\n   -10.0,    5.533  ,  5.5\n    -5.0,    4.232  ,  5.3\n     0.0,    3.265  ,  5.1\n     5.0,    2.539  ,  5.0\n    10.0,    1.990  ,  4.8\n    15.0,    1.571  ,  4.7\n    20.0,    1.249  ,  4.5\n    25.0,    1.000  ,  4.4\n    30.0,    0.8057 ,  4.3\n    35.0,    0.6531 ,  4.1\n    40.0,    0.5327 ,  4.0\n    45.0,    0.4369 ,  3.9\n    50.0,    0.3603 ,  3.8\n    55.0,    0.2986 ,  3.7\n    60.0,    0.2488 ,  3.6\n    65.0,    0.2083 ,  3.5\n    70.0,    0.1752 ,  3.4\n    75.0,    0.1481 ,  3.3\n    80.0,    0.1258 ,  3.2\n    85.0,    0.1072 ,  3.2\n    90.0,    0.09177,  3.1\n    95.0,    0.07885,  3.0\n   100.0,    0.06800,  2.9\n   105.0,    0.05886,  2.9\n   110.0,    0.05112,  2.8\n   115.0,    0.04454,  2.7\n   120.0,    0.03893,  2.6\n   125.0,    0.03417,  2.6\n   130.0,    0.03009,  2.5\n   135.0,    0.02654,  2.5
TEXT 1888 520 Left 0 !.SUBCKT NTC_B 1 2  R0={R0} B={B}\n*.PARAM R0=10000\n*.PARAM B=3988\n.PARAM TK=273.15\n.PARAM T0=25\nRP 1 2 1G\nB1 1 2  I=V(1,2)/{R0*exp(B*(1/(TEMP+TK)-1/(T0+TK)))}\n.ENDS
TEXT 1512 472 Left 0 ;NTC 10k, B=3988  with no selfheating
TEXT 1648 416 Left 0 ;NTC_B\nR0=10K B=3988