Version 4
SHEET 1 2012 1104
WIRE 208 96 208 32
WIRE 544 32 208 32
WIRE 544 80 544 32
WIRE 544 128 448 128
WIRE 544 192 544 160
FLAG 208 176 0
FLAG 544 192 0
SYMBOL voltage 208 80 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value PULSE(0 12 0 1m)
SYMBOL PTC_resistor 528 64 R0
SYMATTR InstName U1
SYMATTR SpiceModel PTC_SHKC004P
TEXT -184 248 Left 0 !.SUBCKT PTC_SHKC004P 1 2 3 \n* Model of Thermometrics type PTO for overcurrent protection, 60 degree transition temperauture part#RL3006-50-60-26-PTO \n* Digikey part# KC004P\n* Data sheet at http://www.thermometrics.com/assets/images/pto.pdf\n* Based on testing 1 unit.\n* The thermal time constant of the die is modeled as an RC time constant fed by a current source representing power.\n* RTH represents the die thermal resistance to ambient and CTH represents the device thermal capacity.\n.param RTH=141 TAU=120 CTH={TAU/RTH} \n* The temperature limit the highest temperature data is available for.  Actual maximum operating temperature may be less than this.\n.PARAM TLIM=130\n* PTC is modeled by a spline of two powers of temperature times a linear negative tempco. \n.param a=-0.0706 b=8.7557 c=34.4342 d=0.2612 f=94.03 g=0.917 h=15.179 j=-0.0744 Rmin=40\nRT1 5 2 R=MAX(exp(d*IF(V(3)>=f , ((V(3)+{h-f})**g-{h**g})/{g*h**(g-1)} , ({c**j}-({f+c}-V(3))**j)/{j*c**(j-1)})+a*(V(3)-f)+b),Rmin) \n* A zero volt source is in series with the thermistor network to act as a current sensor for the power model.\nVRT 1 5 0 \n* V(4) represents ambient temperature\nVAMB 4 0 {TEMP}\n* V(3,4) represents the temperature rise of the thermstor element\n* The current from BTP represents the instantaneous power dissipated in the die (1 volt represents 1 watt)\nBTP 4 3 I=MAX ( V(1,2)*I(VRT), 0 )\nRTH 3 4 {RTH}\nCTH 3 4 {CTH}\n* D1 is a clamp that limits the temperature caused by self heating to no more than TLIM.\n* If the ambient is greater than TLIM, the self heating is clamped to 0.  \n* Aids operating point convergence.  Has no effect on result if die temperature is below TLIM.  \n* Part of self heating that would push temperature above TLIM, is reduced to 1% of normal.\nD1 3 4 ClampDiode \n.model ClampDiode D(RON={RTH/100} ROFF={RTH*1MEG} VFWD={MAX(TLIM-TEMP,0)})\n.ENDS
TEXT -176 152 Left 0 !.op
TEXT -176 56 Left 0 !.step temp -55 140 1
TEXT -176 104 Left 0 !.step V1 -24 24 1