Version 4 SHEET 1 2012 1104 WIRE 208 96 208 32 WIRE 368 32 208 32 WIRE 368 80 368 32 WIRE 368 128 288 128 FLAG 368 160 0 FLAG 208 176 0 SYMBOL voltage 208 80 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value 1 SYMBOL PTC_resistor 352 64 R0 SYMATTR InstName U1 SYMATTR SpiceModel PTC_SH130 TEXT -184 248 Left 0 !.SUBCKT PTC_SH130 1 2 3 \n* Model of BC PTC 130 degree thermistor for temperature sensing, part# 2322 671 91109\n* Data sheet at http://www.vishay.com/docs/29012/23226719.pdf\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=150 TAU=2 CTH={TAU/RTH} \n* PTC is modeled by a spline of two powers of temperature times a linear negative tempco. \n.param a=-0.002894 b=6.8806 c=43.2888 d=0.4541 f=131.5483 g=0.5185 h=0.9338 j=-5.7959\nRT1 5 2 R=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) \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 temperature limit the highest temperature data is available for. Actual maximum operating temperature may be less than this.\n.PARAM TLIM=180\n* The current from BTP represents the power dissipated in the die (1 volt represents 1 watt)\n* and is limited to no less than zero and no more than what will push the temperature up to TLIM through RTH.\nBTP 4 3 I=LIMIT(V(1,2)*I(VRT) , (IF(TEMP