標題: 那位好心的大哥有白光LED 的SPICE MODEL啊? [打印本頁] 作者: raingosi 時間: 2008-7-28 11:26 PM 標題: 那位好心的大哥有白光LED 的SPICE MODEL啊? 那位大哥有LED 的SPICE MODEL啊?(LED电流在350mA到1A）
仿真时不知道怎么将LED等效啊。
希望能给我发个啊，谢谢了！！！
我的油箱raingosi@yahoo.cn和 raingosi@163.com 两个都是。作者: allentel 時間: 2008-7-30 01:28 PM
Since the semiconductor material is not a perfect conductor, some resistance is in series with this constant voltage load, see Figure 2.4. This means that the voltage drop will increase with current. The ESR (equivalent series resistance) of a low power 20mA LED is about 20 ohms, but a 1W350mA LED has an ESR of about 1–2 ohm (depending on the semiconductor material used). The ESR is roughly inversely proportional to the current rating of the LED. The ESR will have production variations too.
The ESR can be calculated by measuring the increase in forward voltage drop divided by the increase in current. For example, if the forward voltage drop increases by from 3.5V to 3.55V (a 50mV increase) when the forward current goes from 10mA to 20mA (a 10mA increase), the ESR will be 50 mV/10mA=5 ohms.
the Zener diode is shown as a perfect device. In reality, Zener diodes also have ESR, which can be higher than the ESR of an LED. For initial testing of an LED driver, a 5 W, 3.9V Zener diode can be used to replace the (white) LED. If the driver is not working as planned the Zener diode may be destroyed, but this is far less costly than destroying a power LED. Since the Zener diode does not emit light, the test engineer will not be dazzled.
[attach]4629[/attach]作者: andy2000a 時間: 2010-5-26 04:25 PM
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