仿真发现白光LED的导通电压是正温度系数,为什么?

confiope

白光LED的模型如下,仿真发现器温度系数是正的,
也就是温度越高,导通电压越大,140摄氏度时,达到3.5V多,
常温才3.1V,这是为什么呢, 请高手帮忙解答,下面是LED的模型.
section wled
model wled  diode
+level = 1
+allow_scaling=yes dskip=no
+is=2e-17
+n=3.4
+rs=0.1
+rl=1e6
+cjo=100p
endsection wled
endlibrary schottky Diode

gaojun927

diode的模型很简单，你查查手册就很清楚了：为了得到3v的导通电压，与正常的二极管比，模型修改了参数n，但n同时也会影响温度特性。

confiope

回复 2# gaojun927


    谢谢,我再摸索看看

evlvu

有时间逛bbs不如自己动手google一下

The TCV(voltage temperature coefficient) for a real diode typically has negative values over low current ranges but increases to positive values at higher currents. This is due mainly to the positive temperature coefficient of the bulk resistance which dominates the diode voltage at these levels.

humphreyyu

这个本来就应该是正温度系数吧，是掺杂半导体呢

confiope

回复 4# evlvu


    但是这个模型仿下来,LED导通压降高温比常温要多20%左右.太离谱了